CBM in adolescents

RUNNING HEAD: CBM in adolescents

Is Cognitive Bias Modification training truly beneficial for adolescents?

Stella W. Y. Chan 1, 4, Jennifer Y. F. Lau2, Shirley A. Reynolds3, 4

1 Section of Clinical Psychology, University of Edinburgh, UK

2 Department of Psychology, King’s College London, UK

3 University of Reading, UK

4 University of East Anglia, UK

Word count: 6969

Disclaimer: No conflict of interest.

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CBM in adolescents

Abstract

Background: Cognitive Bias Modification (CBM) has been shown to change

interpretation biases commonly associated with anxiety and depression and may help

ameliorate symptoms of these disorders. However, its evidence base for adolescents is

scarce. Previous results have been hard to interpret because of methodological issues.

In particular, many studies have used negative bias training as the control condition.

This would tend to inflate any apparent benefits of CBM compared to a neutral

control. Most studies also only examined the effects of a single training session and

lacked follow up assessment or ecologically valid outcome measures. Method:

Seventy-four adolescents, aged 16-18 years, were randomised to two sessions of

CBM training or neutral control. Interpretation bias and mood were assessed three

times: at baseline, immediately post-training, and one week post-training. A

controlled experimental stressor was also used, and responses to everyday stressors

were recorded for one week after training to assess responses to psychological

challenges. Feedback for the training programme was collected. Results: The CBM

group reported a greater reduction in negative affect than control participants.

However, other hypothesised advantages of CBM were not demonstrated. Regardless

of training group, participants reported increased positive interpretations, decreased

negative interpretations, reduced depressive symptoms and no change in trait anxiety.

The two groups did not differ in their stress reactivity. After controlling for group

differences in training performance, all the mood effects disappeared. Conclusions:

When tested under stringent experimental conditions the effects of CBM in healthy

adolescents appear to be minimal. Future studies should concentrate on participants

with elevated cognitive biases and / or mood symptoms who may be more sensitive to

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CBM in adolescents

CBM. Keywords: Cognitive Bias Modification, interpretation, adolescence,

depression, anxiety, stress reactivity.

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CBM in adolescents

Adolescence is a developmental stage when we see a sudden increase in mood

disorders (Kessler et al., 2007). However, research on young people’s mental health

is relatively scarce. Drawing upon the literature with adults, negatively biased

emotional processing is a key cognitive characteristic of anxiety and depression

(Beck, 2008). In addition to people suffering from these disorders (Mathews &

MacLeod, 2005), these biases have also been found in vulnerable (Chan, Goodwin, &

Harmer, 2007) and recovered individuals (Elliott et al., 2012) suggesting that they

could be trait vulnerability markers for mood disorders.

Based on the above, we would expect that therapeutic approaches targeting the

reversal of cognitive biases could reduce risk for and symptoms of emotional

difficulties. While Cognitive Behavioural Therapy explicitly seeks to help individuals

challenge their unhelpful thinking patterns (Beck, 2005), Cognitive Bias Modification

(CBM; Mathews & Mackintosh, 2000) targets automatic and implicit processing

biases. CBM is delivered as a computerised paradigm that coaches individuals to

resolve ambiguous situations in a positive or benign direction. Although originally

designed as an experimental task, CBM has since been tested as a potential treatment

tool for anxiety (Beard, 2011; MacLeod & Mathews, 2012) and, to a lesser extent,

depression (Blackwell & Holmes, 2010). There have been several recent meta-

analyses of CBM studies in adults with broadly similar findings of a small but

significant effect on anxiety and depression symptoms (Hallion & Ruscio, 2011;

Menne-Lothmann et al., 2014), with some support that these effects emerged only

when provoked by stress (Hallion & Ruscio, 2011).

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CBM in adolescents

Given that interpretation biases have also been demonstrated in young people with

symptoms of and / or risk factors for mood disorders (e.g. Dearing & Gotlib, 2009;

Miers, Blote, Bogels, & Wastenberg, 2008), CBM has great potential to be developed

as a therapeutic or preventative tool for adolescents. Six studies have tested CBM in

adolescents (Fu, Du, Au, & Lau, 2013; Lau, Belli, & Chopra, 2012; Lau, Molyneaux,

Telman, & Belli, 2011; Lothmann, Holmes, Chan, & Lau, 2011; Salemink & Wiers,

2011; Telman, Holmes, & Lau, 2013). Although all concluded that CBM is effective

in facilitating positive interpretations, four (Lau et al., 2011, 2012; Lothmann et al.,

2011; Telman et al., 2013) compared CBM against negative training. Due to a lack of

baseline measure, these studies could not rule out the possibility that the observed

group differences might be due to the adverse impact of negative training rather than

benefits of CBM. Only two studies have compared CBM with ‘neutral’ training,

where participants resolved a balanced amount of positive and negative

interpretations. Although the cognitive effect of CBM was replicated in Salemink and

Wiers (2011), Fu et al. (2013) found no cognitive changes using an interpretation bias

questionnaire suggesting that the effect was not robust enough to be generalized into

another form of assessment. This weak effect promoted the authors to question if

resolving equal numbers of positive and negative scenarios really provides a ‘neutral’

comparison group.

The effects of CBM on mood have also been inconsistent. Half of the studies reported

no effect on mood (Fu et al., 2013; Lau et al., 2012; Salemink & Wiers, 2011).

Where group differences were observed, the effects tended to be driven by adverse

effects of negative training (Lau et al., 2011; Lothmann et al., 2011; Telman et al.,

2013). These null results could also be due to the lack of sensitivity in measures of

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CBM in adolescents

mood. All the adolescent studies (except Salemink & Wiers, 2011) used simple visual

analogue scales (VASs) and no studies used validated measures of depressive

symptoms.

The lack of consistent mood effect may also reflect a lack of meaningful provocation

as only two studies assessed mood following a stressor. Lau et al. (2012) found that

CBM led to less increase in anxiety after a mental arithmetic stress task. In Telman et

al. (2013), CBM participants appraised recent stressful life events as having ‘less

impact’ but did not differ from controls on perceived ‘controllability’ or ‘coping’.

This study also relied on retrospective recall of stress rather than contemporaneous

assessment and might therefore be subject to memory bias.

Finally, all of these studies only examined one training session. Many of these

findings could not be fully interpreted due to a lack of comprehensive baseline

measures. None has tested the durability of effects. No previous studies have

systematically collected feedback to establish the acceptability of the training task in

the adolescent population.

Study Objectives

Taken together, although previous adolescent studies claimed to offer some

supportive evidence, a critical analysis of the results presents a less optimistic picture.

Some of the null effects however may arise from methodological issues. This study

therefore aimed to evaluate the effects of CBM in adolescents using an improved

methodology. Specifically, this study sought to 1) compare CBM with a neutral

condition to disentangle whether training effects arise from CBM or simply from

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CBM in adolescents

adverse effects of negative training, 2) expand the training programme to two sessions

to see if effect sizes of training increase, 3) assess outcomes across three time points

to enable comparison between baseline, immediately post-intervention and one week

follow-up, 4) improve and extend the assessment of mood by using detailed symptom

measures rather than crude VASs, 5) assess reactivity to both experimentally induced

and naturally occurring stressors, and 6) examine the acceptability of the intervention

through collecting feedback and identify areas for future improvement.

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CBM in adolescents

METHODS

Participants

This study was approved by the University of East Anglia Research Ethics

Committee. As the primary aim was to investigate CBM in more stringent

experimental conditions, an unselected sample of participants was therefore deemed

to be suitable for the purpose. Seventy-four adolescents (age range = 16-18, mean =

16.64, SD = 0.67) were recruited from a sixth form college in Cambridgeshire, UK.

The majority were female (90.5%), ethnically White (94.6%), native English speakers

(91.9%), and 100% considered themselves ‘fluent in English’. Individuals who

reported any current or past psychological disorders or severe reading difficulties

were excluded. Participants were randomized into CBM or control group (n = 37 per

group) stratified by gender using a block randomization approach. There were no

group differences in demographics (all p’s > .12; see Table 1). At the time of planning

this study, only three CBM studies with adolescents were available (Lau et al., 2011;

Lothmann et al., 2011; Salemink & Wiers, 2011). The relevant effect sizes (i.e. group

differences in post-training interpretation biases) of these studies ranged between

medium to large (d = 0.40 - 1.03). Power calculation based on the average of these

figures (0.71) suggested that 31 participants per group were required to reach a power

of 0.8 (Howell, 2002). The present sample size was therefore deemed to be adequate.

[Insert Table 1]

Procedure

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CBM in adolescents

The overview is shown in Figure 1. After giving written informed consent,

participants met the experimenter at their school’s computer laboratory three times in

small groups (size 1 to10). Seating was arranged such that they could not observe

each other’s responses. At Time 1, participants completed the baseline assessment of

interpretation bias, the Positive Affect and Negative Affect Scale (PANAS), State and

Trait Anxiety Inventory (STAI), and Beck Depression Inventory 2nd ed. (BDI-II).

They then underwent the first session of the CBM or control training. At Time 2,

participants completed the second session of the training, followed by the post-

intervention assessment of interpretation bias, PANAS, and an experimental stressor.

Time 1 and Time 2 were on consecutive days, although four participants (two from

each group) attended them within the same day due to scheduling problems. During

the following week, participants gave daily self-ratings of mood and events. Time 3

took place one week after the intervention, during which interpretation bias, PANAS,

STAI, and BDI-II were repeated. Finally, participants completed a feedback form,

were debriefed and entered into a lucky draw for a £100 retail voucher.

[Insert Figure 1]

Intervention

CBM training

This study used the original CBM paradigm (Mathews & Mackintosh, 2000) adapted

for adolescents (Lothmann et al., 2011). Two sessions were provided with the aim to

expand beyond the single session approach that had so far been the norm in previous

CBM studies with adolescents. This dose was also determined after taking into

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CBM in adolescents

account the school’s concerns over the burden to students (e.g. time) and availability

of resources (e.g. limited computing facilities). Based on the known effect of mental

imagery on CBM (Holmes, Mathews, Dalgleish & Mackintosh, 2006), each session

started with a short imagination exercise, which asked participants to imagine biting

into a lemon (Lothmann et al., 2011). Participants were reminded throughout the task

to imagine the scenarios ‘as happening to yourself’.

The training phase started with a practice trial. A series of ambiguous scenarios were

presented on a computer screen. Each ended with a word fragment that resolved the

ambiguity in a positive way. Participants completed the word fragment by typing in

the first missing letter(s), and then answered a ‘comprehension question’ designed to

emphasise the positive resolution. This question could only be answered correctly if

the situation had been interpreted in the positive direction. Immediate feedback was

given (‘Correct!’ or ‘Wrong!’). Examples are provided in Appendix.

Training was self-paced over two sessions, each with 40 training scenarios plus 8

‘distractor’ scenarios. The latter prompted participants to make neutral or negative

interpretations, and were added to make the purpose of the training less explicit

(Mathews & Mackintosh, 2000). Scenarios were presented in a random order across

4 blocks in each session on computers using E-Prime 2.0 software.

Control condition

Participants in the control group received two sessions of ‘placebo training’. They

were presented with the same scenarios as in the CBM group, except that the word

fragments did not resolve the emotional ambiguity of the scenarios (see Appendix).

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CBM in adolescents

Therefore, participants were not coached to interpret these situations in any specific

direction. This control training was intended to ensure that the two groups were

exposed to similar materials and engaged in a similar level of attention, activity,

effort, and time commitment.

Measures

Interpretation bias

Interpretation bias was assessed using the Recognition Test (Mathews & Mackintosh,

2000) adapted for adolescents (Lothmann et al., 2011). To reduce practice effect and

repetition of materials, two matched sets of materials (versions A, B) were used in a

counterbalanced order across the three assessments (ABA vs. BAB). The test was

delivered on computers using E-Prime 2.0 software.

During the test, participants responded to ambiguous situations similar to those in the

training. However, this time the word fragment did not disambiguate the situation. A

title was given to each scenario to facilitate later recognition. In the subsequent

recognition phase, participants were shown the titles of the scenarios again, each

followed by 4 ‘recognition statements’. Two statements comprised ‘targets’

representing either a positive or negative interpretation. The other two statements,

known as ‘foils’, conveyed similar emotional valence as the ‘targets’ but included

information that was not explicitly given in the scenarios. Participants rated the

similarity of each statement to the scenarios previously presented on a 4-point scale

ranging between ‘1 = not similar at all’ and ‘4 = very similar’. A positive

interpretation bias was indicated by higher ratings for positive than negative targets.

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CBM in adolescents

The foil statements were designed to assess general response biases (Mathews &

Mackintosh, 2000).

Mood

Three self-report short questionnaires were used; all had established psychometric

properties and have been previously used with adolescents. The Positive and

Negative Affect Schedule (PANAS; Watson, Clark, & Tellegen, 1988) includes two

10-item scales assessing participants’ positive affect (PA) and negative affect (NA) at

the present moment. The Beck Depression Inventory, second edition (BDI-II; Beck,

Steer, & Brown, 1996) is a 21-item scale. The State and Trait Anxiety Inventory

(STAI; Spielberger, Gorsuch, Lushene, Vagg, & Jacobs, 1983) consists of two 20-

item scales measuring anxiety at a specific moment (‘state anxiety’; STAI-S) and as a

general trait (‘trait anxiety’; STAI-T).

Stress reactivity

Two types of stressors were used. First, a controlled experimental stressor assessed

participants’ emotional reaction to, and interpretation of, ambiguous situations. It was

designed specifically for this study to be a real life analogue to the training materials.

At the end of the second meeting, participants were told that the computer would now

analyse their data. After a brief pause, an error message was shown on the computer

screen saying that ‘We are sorry but we were unable to analyse your data. There is a

possibility that some or all of your responses have not been properly recorded. This is

a very unusual problem’. Participants were shown five possible explanations of why

this error might have occurred and asked to rate on a 4-point scale the likelihood of

each explanation (1 = ‘not at all likely’ vs. 4 = ‘very likely’). Three of the options

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CBM in adolescents

represented negative interpretations by implying that it might be the participant’s fault

(e.g. ‘You have not followed the task instructions correctly’) and two were benign

interpretations (e.g. ‘There was a temporary power cut’). These statements were

presented in a random order. To mask the true experimental purpose, the instruction

was worded as a request to help experimenters to identify the problem. The average

ratings for the positive and negative statements were used as the outcome variables. In

addition, emotional responses were measured by a 5-point Likert rating scale on a

subset of five items drawn from the PANAS (Proud, Excited, Distressed, Nervous,

Guilty) specifically chosen for their relevance to the situation. At the end participants

were assured that the error was not their fault.

Second, reactions to everyday stressors were explored. In the week following the

training phase, participants were asked to rate how they felt each day using a 5-point

scale (1 = ‘completely miserable or stressed’ vs. 5 = ‘really good’). They were also

asked to describe any events that ‘made you feel particularly good or bad’ via email

or mobile phone text messages, according to individual preferences. The experimenter

sent a reminder each day at 18:45 ± 30 minutes.

Feedback

At the end of the study, participants were asked to fill in a feedback form. Participants

were asked to indicate whether they would recommend their friends to participate in

the study, what they liked best and liked least about the study, what they thought was

the purpose of the computer task, and were encouraged to leave further comments.

Feedback would be used to establish the overall acceptability of CBM in adolescents

and to gather information that may be helpful in improving CBM in the future.

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CBM in adolescents

Statistical Analysis

Data analyses were conducted using SPSS v18.0. Statistical significance was defined

as p < .05 (two tailed). Where normality assumptions were violated, data were

transformed (BDI-II, PANAS-NA) or analysed by non-parametric tests (stress

reactivity). Boxplots were used to screen for outliers. The key outcome variables were

examined using repeated measures (mixed-design) ANOVAs, in line with many

previous CBM studies (e.g. Fu et al., 2014; Lau et al., 2011, 2012; Lothmann et al.,

2011; Telman et al., 2013); significant interactions were followed by t tests.

Preliminary analyses on training performance revealed that both groups achieved high

levels of accuracy (≥ 92%), indicating good compliance to task demands. However,

one participant (CBM group) performed very poorly (accuracy > 3 standard

deviations below mean), suggesting that training was not received as intended and

was excluded from all analyses. In addition, eight participants did not attend Time 3

assessment (three from CBM group, five from Control group). This dropout rate did

not differ significantly between groups (z = 0.75, p = .45). These participants did not

differ from those who completed the study in terms of demographic data and baseline

mood and cognitive measures (all p’s > .08).

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CBM in adolescents

RESULTS

Baseline Characteristics

At Time 1, negative interpretation bias was significantly correlated with depression

and anxiety, and most of the mood measures were inter-correlated (see Table 2). The

two groups were matched in baseline mood and interpretation bias (all p’s > .14; see

Table 3 and Figure 2).

[Insert Tables 2, 3, & Figure 2]

Training Effects on Interpretation Bias

A repeated measures ANOVA was conducted with two between-subjects factors

(Group: CBM vs. Control; Order: ABA vs. BAB) and three within-subjects factors

(Time: T1 vs. T2 vs. T3; Type: target vs. foil; Valence: positive vs. negative). Due to

two significant interactions involving Type, responses for targets (interpretation bias)

and foils (response bias) were analysed separately in line with Lothmann et al. (2011)

and Mathews & Mackintosh (2000). See Figure 2.

Targets: There was a significant Time x Valence interaction, F (2,122) = 10.10, p

< .001, such that participants increased their ratings for positive targets, t (64) = 3.48,

p = .001, d = 0.43, 95% CI [-0.26, -0.07], but reduced their ratings for negative

targets, t (64) = 2.03, p = .047, d = 0.25, 95% CI [0.002, 0.24], from Time 1 to Time

2. The increase in positive interpretation was still present at Time 3 (Time 1 vs. Time

3: t (64) = 4.23, p < .001, d = 0.52, 95% CI [-0.32, -0.11]) but not the decrease in

negative interpretation (Time 1 vs. Time 3: t (64) = 1.57, p = .12, d = 0.19, 95% CI [-

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CBM in adolescents

0.03, 0.22]). Thus, both interventions increased positive and reduced negative

interpretations immediately and this was sustained for one week for positive

interpretation. However, the crucial Time by Valence by Group interaction was not

significant, F (2,122) = 0.12, p = .89, nor was the main effect of Group, F (1, 61) =

0.70, p = .41, suggesting that CBM was no different from Control.

Foils: Similar results were yielded, with a significant Valence x Time interaction, F

(2,122) = 13.98, p < .001 driven by an increase in positive response bias, t (64) =

4.28, p < .001, 95% CI [-0.33, -0.12], and a decrease in negative response bias, t (64)

= 2.01, p = .049, 95% CI [0.0006, 0.22], between Time 1 and Time 2. The increase in

positive response bias was still present at Time 3 (Time 1 vs. Time 3: t (64) = 4.49, p

< .001, 95% CI [-0.34, -0.13]) but not the decrease in negative interpretation (Time 1

vs. Time 3: t (64) = 1.04, p = .30, 95% CI [-0.05, 0.17]). Likewise to ‘targets’, there

was no Time x Valence x Group interaction, F (2, 122) = 0.47, p = .63, or main effect

of Group, F (1, 61) = 3.63, p = .06, suggesting no group difference.

Training Effects on Mood

Each of the mood measures was analysed by a repeated measures ANOVA with

Group as a between-subjects variable and Time as a within-subjects variable (see

Table 3 for means, standard deviations, and full statistical results).

BDI-II: BDI-II scores reduced in both groups from Time 1 to Time 3, but there was

no between-group difference or Time x Group interaction.

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CBM in adolescents

STAI-S: One outlier (CBM group) was excluded from analyses for this measure. State

anxiety increased from Time 1 to Time 3. However, a significant Time x Group

interaction showed that this increase in anxiety was only reported in the Control, t

(31) = 3.08, p < .01, d = 0.54, 95% CI [-8.36, -1.70], but not in the CBM group, t (31)

= 0.06, p = .96, d = 0.01, 95% CI [-3.28, 3.47]. There was no significant main effect

of group.

STAI-T: There were no significant effects of time, group or the interaction on trait

anxiety.

PANAS-PA: There was a significant main effect of Time, suggesting an overall

reduction in PA over time. There was no main effect of or interaction with Group

PANAS-NA: One outlier (CBM group) was excluded from analyses for this measure.

Results suggested a significant main effect of time indicating an overall reduction in

NA, and a significant Group x Time interaction. CBM group demonstrated a

reduction in NA from Time 1 to Time 2, t (30) = 5.32, p < .001, d = 0.96, 95% CI

[0.49, 1.11], and an increase in NA from Time 2 to Time 3, t (30) = 2.09, p = .045, d

= 0.37, 95% CI [-0.81, -0.01]. Negative Affect at Time 3 was significantly lower than

Time 1, t (31) = 2.05, p = .049, d = 0.36, 95% CI [0.001, 0.87]. By contrast, no

significant change was found within the Control group: Time 1 vs. Time 2, t (31) =

0.78, p = .44, 95% CI [-0.24, 0.53]; Time 2 vs. Time 3, t (31) = 1.70, p = .10, 95% CI

[-0.86, 0.08]; Time 1 vs. Time 3, t (31) = 0.92, p = .37, 95% CI [-0.78, 0.30].

Independent samples t tests indicated no group differences in PANAS-NA scores at

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CBM in adolescents

Time 1, t (62) = 0.95, p = .35, 95% CI [-0.26, 0.73], Time 2, t (61) = 1.67, p = .10,

95% CI [-0.92, 0.08], or Time 3, t (62) = 1.43, p = .16, 95% CI [-1.06, 0.18].

Training Effects on Stress Vulnerability

Responses to experimental stressor

Data were non-normal even after transformation; therefore the Wilcoxon Signed Rank

Tests and Mann-Whitney U Tests were used. Participants, regardless of group, rated

the benign explanations as more likely than the negative explanations (p < .01), and

reported more positive than negative affect following the stressor (p < .001).

However, there were no significant group differences (all p’s > .14).

Responses to day-to-day stress

Daily mood ratings were non-normal even after transformation. Mann-Whitney U

Tests revealed no group difference in mood ratings on any day (all p’s > .61).

Training Performance as a Covariate

CBM group was more accurate than Control in responding to the comprehension

questions during the training sessions, F (1, 70) = 16.01, p < .001, which might

potentially mediate any group difference in training effects (Lothmann et al., 2011).

To test this hypothesis, all analyses were re-run with training accuracy as a covariate.

The effects on interpretation biases remained, but all the effects on mood disappeared.

Participants’ Feedback

Feedback was mixed. Although 98% said that they would recommend their friends to

take part in the study, 74% said that the training tasks were too long or that the

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CBM in adolescents

scenarios were too repetitive or stereotyped. Most participants (94%) correctly

guessed the purpose of the CBM intervention. When asked what their favourite

part(s) of the study was, the most common replies were the questionnaires (30%) and

that the study made them more aware of their feelings, personality, and / or the way

they dealt with day-to-day situations (30%) and the daily reporting of mood and

events (14%).

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CBM in adolescents

DISCUSSION

This study set out to ask: Is Cognitive Bias Modification truly beneficial for

adolescents? We designed the study to increase internal and external validity by

amending the control condition, lengthening the training period, including a follow

up, using standardised measures of mood and symptoms, and testing the effects of

CBM under the provocation of both experimental and real life stressors. Participants

who received the CBM intervention reported a greater reduction in negative affect

than the control group and did not experience the increase in state anxiety reported by

control participants. However, other hypothesised advantages of CBM were not

demonstrated; both groups reported increased positive interpretations, decreased

negative interpretations, reduced depressive symptoms and positive affect, and no

change in trait anxiety. There were no group differences in stress reactivity. After

controlling for group differences in training performance, all the mood effects

disappeared. Therefore, this study did not yield evidence to support the effectiveness

of two sessions of CBM in healthy adolescents.

We used a neutral control condition where participants were not coached to interpret

ambiguous scenarios in any specific direction. This has advantages over using

negative training as the control condition, which was the case in two-thirds of

previous adolescent studies (see Introduction). Negative training is useful to test

causal relationships between cognitive biases and mood in an experimental setting.

However, to assess the therapeutic potential of CBM it must be compared to placebo

or to active interventions. Similarly, balanced training may not provide a suitable

control if it significantly alters participants’ usual interpretation style in either a

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CBM in adolescents

positive or negative direction. Participants with predominantly negative biases may

be more affected by the negative items than the ‘balanced’ amount of positive items.

Alternatively, 50% of positive training may be sufficient to inducing positive

interpretations. Hence, balanced training does not guarantee a neutral outcome.

However, it is important to acknowledge that not coaching participants to resolve the

emotional ambiguity of scenarios might not be completely ‘neutral’ either as it might

have simply reinforced participants’ pre-existing biases. Future studies should

consider including both negative training and a neutral condition as comparison

groups.

In contrast to many previous studies with adults (Hallion & Ruscio, 2011; Menne-

Lothmann et al., 2014) and, to a limited extent, adolescents, CBM did not modify

interpretation biases in an unselected group of healthy adolescents more than

exposure to neutral training. Thus, it appears that CBM may not be effective when

comparing to a ‘neutral’ control. These findings are consistent with a recent meta-

analysis of adult data where significant training-associated changes mostly emerged in

the comparison with negative rather than neutral / no training (Menne-Lothmann et

al., 2014). Also consistent with our data, a recent study (Micco, Henin, & Hirschfeld-

Beker, 2014) showed that even four sessions of CBM (i.e. double the current dose)

did not alter interpretation biases or symptoms of depression and anxiety when a

neutral control was used. Notably, this finding was yielded in depressed adolescents,

suggesting that pre-existing low mood may not moderate the effects of CBM.

Although this study did find that a small subgroup of participants who were depressed

and had baseline negative interpretation biases (n= 9) showed cognitive changes,

these cognitive changes did not translate to mood improvement suggesting that pre-

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CBM in adolescents

existing negative bias may moderate changes in cognitive bias but not necessarily

mood symptoms.

Indeed, CBM research in the adult population has raised questions about potential

moderators. Many have hypothesised that individuals with clinical levels of mood

symptoms may show a larger extent of change. Although an earlier meta-analysis did

not find a significant moderation relationship (Hallion & Ruscio, 2011), a later meta-

analysis that capitalised on more studies did (Menne-Lothmann et al., 2014). Other

suggested moderators concern the characteristics of training and the cognitive

strategies by which participants process the training materials, such as social

comparison (Standage, Harris, & Fox, 2013). Studies with adolescents have also

tested potential moderators such as pre-existing negative bias, trait anxiety and self-

efficacy but results have been patchy (see review in Lau et al., 2013). The present

study improved on many previous studies with adolescents by using validated

measures for depression and anxiety. The mood effects of CBM appeared to be driven

by the CBM group being more accurate in CBM training rather than the training per

se. Higher accuracy in the CBM group means that this group had received more

positive feedback in training, which may encourage a positive mood shift (Lothmann

et al., 2011). These mixed effects on mood are consistent with recent research on

CBM with young people (Lau, 2013; Salemink & Wiers, 2011), and a recent meta-

analysis that accounted for publication bias (Hallion & Ruscio, 2011).

A novel feature of the current study is that it assessed responses to both

experimentally induced and naturally occurring stressors. This is an important aspect

of evaluating CBM and assessing its effect beyond the laboratory. Data collection via

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CBM in adolescents

text messaging was popular and effective (with minimal missing data) and suggests

that this is a feasible way of collecting ‘real life’ data from young people.

The null effect of CBM on stress reactivity is consistent with previous research with

adults (e.g. Hertel, Vasquez, Benbow, & Hughes, 2011; Salemink, van den Hout, &

Kindt, 2009; Steinmain & Teachman, 2010; Teachman & Addison, 2008). While a

small number of studies yielded supportive evidence using a stress task or mood

induction (Holmes, Lang, & Shah, 2009; Wilson, MacLeod, Mathews & Rutherford,

2006), many studies illustrated that CBM reduced anticipatory anxiety rather than

actual anxiety in the situation (Hirsch, Mathews, & Clark, 2007; Murphy, Hirsch,

Mathews, Smith & Clark, 2007). Studies that have employed a stressor have also

varied greatly in terms of the nature of the stressor and measurement tools, rendering

it difficult to compare across these findings.

Furthermore, experimental stressors used in previous studies have mostly targeted

anxiety. As this study was interested in a wider range of mood outcomes, the stressor

used in the present study was specifically developed to capture the type of negative

biases known to be relevant for depression. The error message was deliberately

ambiguous and could be taken to imply that a participant has done something wrong,

which would likely have triggered the negative sense of self commonly observed in

depression (Beck, Rush, Shaw, & Emery, 1979). The stressor was also designed to be

age appropriate and fit into the context of the experiment. More than 10 participants

asked the experimenter for advice when they saw the error message, suggesting some

face validity. However, in hindsight, it would have been helpful to ask whether

23

CBM in adolescents

participants believed in the error message at the end of the study. A more formal

validation process is needed before it could be used as a robust experimental tool.

While this study set out to overcome methodological limitations of previous

investigations, a number of weaknesses should be noted. Sample size was determined

a priori. However, it would be more accurate to base the power calculation upon

studies that compared CBM training against neutral training (rather than negative

training) in adolescents. To date only three such studies exist (Salemink & Wiers,

2011; Fu et al., 2013, Micco et al., 2014); the latter two were published after data

collection was completed in this study. The relevant effect sizes reported were

medium to large (d = 0.40 - 1.26); power calculation based on the average of these

figures (0.78) suggests that 30 per group would be sufficient. Again, the current study

seems adequate. However, two of these studies used clinical samples (anxious

adolescents in Fu et al., 2013; depressed youth with pre-existing negative bias in

Micco et al., 2014), which would likely to have yielded a larger effect size. Taken

together, while there is no consistent evidence to suggest that this study is under-

powered, future studies should aim to recruit a larger sample that will also enable

further analyses to unpick moderation and mediation relationships. Secondly, the

‘dose’ of training may have been insufficient, as more sessions appeared to have

yielded larger effects in the adult population (Beard, 2011). However, it should be

noted that our null results are consistent with Micco et al. (2014) using a double

training dose. Indeed, the evidence for the advantage of multiple training sessions has

been mixed in recent meta-analyses with adult data with one study finding in support

(Menne-Lothmann et al., 2014) and another not (Hallion & Ruscio, 2011). Future

research specifically designed to track the training effects across sessions would be

24

CBM in adolescents

helpful in clarifying the minimum dose needed for change. Thirdly, this was the first

adolescent study to collect detailed participants’ feedback. Although 98% would

recommend this study to friends, many reported finding the task too long or the

scenarios too ‘stereotyped’. These limitations are not unique to this study but

nevertheless might have compromised the training effects. Finally, future studies

should aim to include a longer follow-up assessment.

CONCLUSION

CBM research with adolescents is still at an early stage. In a recent review, Lau

(2013) argued that CBM might be a useful preventative tool for young people at risk

for mood disorders. This study incorporated several methodological features that

greatly improved internal and external validity. CBM did not change adolescents’

interpretation biases or impact on their mood, symptoms or responses to laboratory or

real life stressors. The result of this study, though not conclusive, highlight that the

effect of CBM in adolescents may be much weaker than previously assumed and that

wider applications in this age group need to be considered with caution until further

evidence emerges.

25

CBM in adolescents

26

Key points:

• There is an increasing evidence base for the use of CBM in treating mood disorders in adults through reducing negative interpretation biases.

• Only limited research has been extended to adolescents. Most of them might have over-estimated the benefits by comparing CBM against negative training.

• This study compared two sessions of CBM against placebo training in adolescents with an improved methodology, including three time-point measures on interpretation bias, mood, and responses to experimental and everyday stressors.

• Our results suggest that CBM does not outperform placebo in healthy adolescents.

• Clinical applications should be considered with caution until further evidence emerges.

CBM in adolescents

Acknowledgement

We thank the students and teachers of the school where data collection took place.

27

CBM in adolescents

Correspondence to:

Dr Stella Chan

Clinical Psychology

University of Edinburgh

Teviot Medical Quad

Edinburgh EH8 9AG

Tel: +44(0)1316513935

Fax: +44(0)1316503891

Email: stella.chan@ed.ac.uk

28

CBM in adolescents

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Table 1

Demographics (n = 37 per group)

Variable CBM Control

Age a

Gender - Female b

16.51 (0.69)

32 (86.5%)

16.76 (0.64)

35 (94.6%)

Ethnicity - White b 34 (91.9%) 36 (97.3%)

English as first language b 33 (89.2%) 35 (94.6%)

Note.

a Values represent group means and standard deviations (in brackets).

b Values represent number of participants and percentage (in brackets).

34

Table 2

Inter-correlation between Baseline Mood and Interpretation Bias (N = 74).

1 2 3 4 5 6

1. Interpretation Bias a N/A .45** .35** .41** - .15 .19

2. BDI-II N/A .60** .86** - .16 .34**

3. STAI-S N/A .69** - .33** .65**

4. STAI-T N/A - .32** .34**

5. PANAS-PA N/A .07

6. PANAS-NA N/A

Note. Values represent Pearson correlation coefficients (r); Statistical significance * p < .05, ** p < .01 (two tailed).

a Interpretation bias was computed by subtracting the mean similarity rating for positive targets from negative targets (Salemink & Wiers,

2011).

35

36

Table 3 Measures of Depression, Anxiety, Positive and Negative Affect

Time 1 Time 2 Time 3 Results

BDI-II

CBM

Control

13.24 (9.57)

11.50 (7.16)

-

-

12.09 (11.34)

9.63 (7.47)

T: F (1, 63) = 11.51, p = .001* (decrease)

G: F (1, 63) = .63, p = .43 ns

T x G: F (1, 63) = .28, p = .60 ns

STAI-S

CBM

Control

38.03 (8.28)

37.16 (8.73)

-

-

37.94 (10.23)

42.19 (10.81)

T: F (1, 62) = 4.51, p = .04 * (increase)

G: F (1, 62) = .65, p = .42 ns

T x G: F (1, 62) = 4.86, p = .03*

STAI-T

CBM

Control

43.76 (11.59)

42.88 (11.12)

-

-

42.81 (13.34)

42.31 (11.64)

T: F (1,62) = 1.51, p = .22 ns

G: F (1,62) = 0.05, p = .82 ns

T x G: F (1, 62) = 0.07, p = .79 ns

PANAS - PA

CBM

Control

29.39 (5.50)

29.16 (5.97)

28.01 (7.09)

26.72 (5.89)

27.55 (8.62)

24.81 (7.12)

T: F (2,124) = 8.17, p < .001* (decrease)

G: F (1, 62) = 0.94, p = .34 ns

T x G: F (2, 124) = 1.30, p = .28 ns

PANAS-NA

CBM

Control

14.06 (3.31)

13.66 (3.26)

11.87 (2.77)

13.16 (3.30)

13.16 (3.72)

15.09 (5.64)

T: F (2,122) = 5.83, p = .004* (decrease)

G: F (1, 61) = 0.84, p = .36 ns

T x G: F (2, 122) = 3.10, p = .049*

Note. Values represent group means and standard deviations (in bracket). Results reported are: T = Main

Effect of Time, G = Main Effect of Group, T x G = Time x Group interaction, * p < .05 (two tailed), post

hoc t tests following significant interactions are reported in the main text.

37

Figure 1

Procedure Overview

38

Figure 2

Similarity Ratings for the Positive (blue) and Negative (red) Target and Foil Statements of the CBM (n = 33) and Control (n = 32) groups

across Time 1 (T1), Time 2 (T2), and Time 3 (T3). Values represent group means and standard errors.

39

Appendix

Example of Training Materials

CBM Training

In each trial, participants read an ambiguous scenario ending with a word fragment

that resolved the ambiguity in a positive way. For example: ‘It is the first day of term.

Your new teacher asks everyone to stand up and introduce themselves. After you have

finished, you guess the others thought you sounded…’ followed by a word fragment

‘cl-v-r’ (clever). Participants completed the word fragment by typing in the first

missing letter (‘e’), and then answered a ‘comprehension question’ designed to

emphasise the positive resolution (‘Do you feel unhappy with your introduction?’).

The ‘correct’ answer was ‘No’.

Control condition

Using the above example, the matched control scenario was: ‘It is the first day of

term. Your new teacher asks everyone to stand up and introduce themselves. After you

have finished, another person gets up to’ followed by a word fragment ‘s-eak’ (speak).

The corresponding comprehension question was ‘Is it the first day of term?’

40