Causes of Mental Illness

7/29/2019 Causes of Mental Illness

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Session 2


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There have been many things that have

been suggested as possible causes of

mental illness.

Different explanations can generally be

divided into three categories:

Biological factors

Social and environmental factors

Psychological make up of the individual

All of these factors are important and

interact with each other.


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1 Biological Factors

Physical things such as brain tumours or

taking street drugs

Genetics

Brain chemistry

Brain structure

Physical development


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Evidence for a genetic element in mental

illness comes from research with twins

and both biological and adoptive relatives

of people with schizophrenia or bi-polar

disorder.

Research has found that the closer the

biological relationship, the greater the riskof a relative also having the diagnosis.


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The estimated probability of being given a

diagnosis of schizophrenia is as follows:

46% for a child with both parents diagnosed

13% for a child with one parent diagnosed

9% for siblings.

This is compared to the overall probability of

1% for the general population.

Similar findings have been reported for

bipolar disorder.


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However, there has been some doubts

raised about the methods used in these

studies and it is very difficult to

differentiate genetic inheritance fromenvironmental factors.

Most studies report that there is evidence

for a combination of genetic andenvironmental factors.


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Schizophrenia could result from anoverproduction of dopamine.

Dopamine is a neurotransmitter or brain

chemical.Some anti-psychotic drugs that effectdopamine can induce parkinsonian type

symptoms, such as shaking.Parkinsonism is known to be related to lowdopamine levels so it is thought that thedrugs work by lowering dopamine levels.


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Drugs such as amphetamines increase

dopamine production and can cause

psychotic like experiences.

However, we can not draw any conclusionsfrom either of these two observations.

The anti-psychotic drugs described have an

immediate effect on dopamine in the brainbut symptoms only improve gradually.


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New drugs such as clozapine effect adifferent neurotransmitter (brain chemical),serotonin. Research is currently taking place

to investigate this.The other major problem here is cause andeffect. It is not known if the chemical changescause the psychotic experience or if the

experience causes the chemical change inthe brain.


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The only well established structuralabnormality in the brain that has been foundin people with psychosis is enlarged lateral

ventricles (fluid filled spaces within the brain).Research suggests that different types ofpsychotic experiences are associated withdifferent patterns in brain activity.

Low levels of activity in the frontal lobes inthe brain have been observed in peopleexperiencing so-called negative symptoms.


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However, the medication that people havetaken over the years is not always taken intoaccount.

It is also possible that psychological traumaor psychotic experiences themselves cause

the changes in brain activity, rather than theother way around.


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Brain scans of London taxi drivers havefound that they have enlargements of certain

brain structures, thought to be due to theamount of information they have had to store.This would suggest that it may be experiencethat causes the changes in brain structuresrather than the changes in brain structurecausing the experience.

Alternatively, one could also suggest that

those who are successful at becomingLondon taxi drivers already have differentbrain structures!


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Physical Development

People with schizophrenia are more likely tohave:

been born in the early months of the year

experienced difficulties during birth

been exposed to viruses in the womb

These are all environmental theories thathave been put forward but evidence is limitedand many of these theories are speculative.


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The evidence for specific biological

mechanisms underlying mental illness is

inconclusive.

Some individuals may be more sensitive toenvironmental stressors than others and this

will be reflected in some way in their brain

chemistry.However, the evidence would suggest that

there are also other factors involved in the

underlying cause of mental illness.


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2Social and EnvironmentalFactors

Stress-Vulnerability Model

Cultural Factors

Social Exclusion

Life Events

Family Relationships


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No one single cause for mental illness hasbeen found and it is likely that many aspectsof an individuals life are significant inproducing psychotic experiences.

This has been described as the stress-vulnerability model. As discussed earlier,everybody has a different level of sensitivityto environmental stressors. This sensitivity is

known as vulnerability.A persons level of vulnerability could becaused by biological factors, discussedearlier, or be a result of events that have

happened previously in a persons life


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Low High

Low

High


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The stress-vulnerability model suggests thatproblems will only occur when environmentalstressors are present.

The amount of environmental stress requiredto cause problems will differ according to thevulnerability of the individual.

This model would explain why some people

develop psychological problems when othersdont even if the have gone through the samestressful events.


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Although psychotic experiences tend to besimilar across different cultures, people indifferent cultures describe psychologicalproblems in very different ways.

Some cultures may describe psychologicalproblems in physical terms (such as pain),whereas other cultures will describe the sameproblems in emotional terms (anxiety).


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Sometimes explanations can be misinterpreted ifthe context in not understood. For example, insome cultures, many people believe in thepossibility of being possessed by demons, but in

other cultures this could be wrongly thought ofas a delusional belief.

It has also been found that the experiences ofpeople from different cultures may be responded

to differently by medical professionals. Forexample, research has shown that black peopleare more likely to receive a diagnosis ofschizophrenia than white people, even if their

experiences are the same.


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Social Exclusion

It has been suggested that social exclusion(e.g. racism) can increase the likelihood of

developing a mental illness.However, such findings require furtherinvestigation.


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Many people who have psychotic experiences

have experienced abuse or trauma at some

point in their lives. They are also likely to have

experienced a greater number of stressfulevents in the 6 months before an episode.

It appears that stress is associated with the

onset of psychotic symptoms in vulnerable

individuals. Also, once someone hasexperienced a psychotic episode, high levels of

stress make it more likely that the problems will

return.


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Difficult family relationships in childhood and

adolescence may be an important contributing factorfor some people.

Research has also found that family can play animportant role in the recovery of a person diagnosedwith a mental illness.

Friends and family of someone who is havingpsychotic experiences can find it difficult to copewith certain behaviours and can become critical orhostile toward the individual. Equally some familiescan find the changes very upsetting and will treatthe individual like they are a child again.These reactions have been described as highexpressed emotion and have been found to lead topoorer outcome during recovery and an increased

likelihood of relapse.


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3 Psychological Approaches

Overview

Cognitive deficits and psychoticexperience

Cognitive biases


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Psychologists usually assume that peoplewho report psychotic experience are eitherhaving unusual perceptual experiences

(hearing voices) or they are interpretingnormal experiences in an unusual way.

Psychologists then look for reasons as towhy this may happen.


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There could be problems with the structure orfunctioning of the brain that can lead to impairmentsin processes such as perception, memory andattention (attention deficits).

Other people may misinterpret normal life events.For example a traumatic event during childhoodcould effect the way which you interpret futureevents (cognitive biases).

All events will be interpreted from the perspectivethat the person has developed. People thereforediffer in the way they respond to different stressesand also the way they understand and make senseof psychotic experiences.


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There is evidence to suggest that somepeople with schizophrenia have difficulties ona variety of measures of attention.

Some people who are having a psychoticexperience lose the ability to interpret otherpeoples actions and speech in order tounderstand what they might be thinking.

Cognitive deficits have been suggested aspossible causes of disorganised speech,hearing voices and unusual beliefs.


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Deficits in information processing can leave

people more vulnerable to psychotic

experiences. When people with these

vulnerabilities experience stressful events,the deficits make it harder for them to cope.

Emotional stress can lead to an increase in

cognitive deficits, which in turn can lead tofurther problems and the development of a

vicious circle.


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Many studies have found that people withunusual or delusional beliefs tend to jump toconclusions when they have limited

information.Research also suggests that unusual beliefsare associated with specific biases inreasoning about social situations.

For example, people who experienceparanoia have a general tendency to assumethat other people cause the things that gowrong in their lives.


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There is also evidence that some people whoexperience auditory hallucinations havedifficulty distinguishing their inner speech(thoughts) from speech from an external

source.This has been shown in brain scans, whereareas of the brain associated with speech areactive when people hear voices.

Also, in other experiments, people who hearvoices have been shown to have difficultywhen they are asked to distinguish betweentheir thoughts and words spoken to them.


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It is possible to understand many psychoticexperiences as a result of how the personsees the world, or particular problems withthought processes or both.

For example, if you are experiencingemotional stress, you might find it hard tointerpret other peoples actions andintentions. This could make interactionsanxiety provoking. If events in your life have

led you to believe that people hurt you atevery opportunity, and you have a tendencyto jump to conclusions, it is understandablethat you might feel paranoid.


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All of the factors that have been discussed areimportant and can interact with each other.

Although there is some evidence that genetics and

brain chemistry and structure are involved in

developing psychosis, the evidence is not conclusive.The evidence suggests that some people are more

vulnerable to environmental stressors than others, but

biological factors alone cannot explain the underlying

causes of mental illness.The stress-vulnerability model suggests that problemswill only occur when environmental stressors arepresent. The amount of environmental stress required

to cause problems will differ according to the


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..Summary Continued

To summarise, there is no single explanationfor the underlying causes of mental illness.

Research over the last few decades has

shown that psychotic experiences areinfluenced by social and psychological factorsas well as biological ones.

When psychological, social and biological

factors interact, especially when stressorsoccur, psychotic experiences can be theresult.

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Causes of Mental Illness