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Leading opinions
Dementia and stroke: the present and future epidemic
Toby Cumming and Amy Brodtmann
Stroke and dementia are closely associated, whether in the
form of vascular cognitiveimpairment or Alzheimers disease.
Alzheimers disease and stroke share very similar risk factor
profiles and may be prevented with similar modification
programs. We aredealingwith a present andfuture epidemic
that will fundamentally affect health care provision in all
high-income countries. At least 35 million people worldwide
currently havedementia. Dementia prevalence is predictedto
double every 20-years: an expected 66 million in 2030, 115
million in 2050. The burden of these diseases is
considerablewhen taken with the annual 15 million people
worldwide
who will suffer stroke. There remains a disconnection be-
tween thenodes and modes of practice of strokeneurologists
and cognitive physicians. As members of a broad medical
community, we need to be aggressively managing vascular
risk factors, as well as developing techniques to address
the
divide between the acute stroke patient of today and the
dementia referral of tomorrow.
Key words: stroke, dementia, aging, cerebrovascular disease
There was a sense of dej vu at the recent International
Conference on Alzheimers disease in Honolulu.The epidemiology,
public health, and prevention platform
sessions presented a familiar message: to prevent or delay
dementia, we need to aim for optimal blood pressure control;
avoid diabetes and, should it occur, manage this
aggressively.
We need to maintain a healthy weight; not smoke; treat other
vascular risk factors such as hypercholesterolaemia; and ex-
ercise, exercise, exercise!
Stroke was again shown to be a strong risk factor for the
development of AD, and in patients with established AD, the
superimposition of stroke was associated with greater cogni-
tive decline and worse prognosis. These associations are not
new, but the strength of the links was confirmed.
We are dealing with a mammoth global health issue, a
present and future epidemic that will fundamentally affect
health care provision in all high- and middle-income coun-
tries. And if the abstracts from Africa and Asia reflect the
prevalence of dementia, low- and middle-income countries
will also have to grapple with how to care for and treat an
ageing and increasingly dementia-affected population (1, 2).
The numbers are sobering: at least 35 million people world-
wide currently have dementia (3), a 10% increase from the
2005 estimate (4). Dementia prevalence is predicted to
doubleevery 20-years: an expected 66 million in 2030, 115 million
in
2050. The burden of these diseases is considerable when
combined with the 2007 WHO stroke estimates, which reflect
an annual, global average of 15 million people who will
suffer
from stroke, leaving 5 million dead and another 5 million
disabled each year (5).
Sowherewere allthe stroke physicians?The converse applies
to the relative absence of cognitive neurologists and
dementia
physicians at stroke meetings. There is a clear
disconnection
between both models of practice. As stroke physicians, we
practise within short-term time frames, addressing acute
issues; how can we reduce morbidity acutely? How can we
improve a survivors Rankin score at 90-days? What is the
advantage of tPA given in the next 3 hs vs. the next 6? What
antiplatelet agent will most effectively prevent future
stroke?
When we follow up our patients, it is usually only for a few
months poststroke to check that all necessary tests have
been
performed, appropriate rehabilitation has been implemented
and patients are on the correct medication. We hardly ever
recommend that they participate in brain banking, even if
this
is available in our region. It is only when they have
further
strokes that we may see them years down the track. So it is
easy
to lose sight of their cognitive trajectory. Despite the
evidence
linking cognitive decline with recurrent stroke, we may fail
to
observe whichpatients remain cognitively normal despite
theircerebrovascular disease, and which do not (6).
Cognitive physicians have a very differentmodel of care. We
painstakingly document the presenting problem, and its
impact on carers and employment. Family history is explored
as well as growth, development, early education, and work.
We
observe. We manage expectantly. Behavioural problems are
anticipated and addressed; patients and families are
supported
along their dementia journey. Often, we encourage participa-
tion in brain banking, as this has been the only means of
definitive diagnosis.DOI: 10.1111/j.1747-4949.2010.00527.x
Correspondence: Amy Brodtmann, National Stroke Research
Institute,
Level 1 Neurosciences Building, 300 Waterdale Road, Heidelberg
3084,
Australia.
E-mail:[email protected]
National Storke Research Institute, Heidelberg, Australia
Conflict of interest: None declared.
& 2010 The Authors.
International Journal of Stroke & 2010 World Stroke
Organization Vol 5, December 2010, 453454 453
mailto:[email protected]:[email protected]
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In thepast,this disconnection may have been partly fostered
by more strident supporters of the amyloid hypothesis, who
have argued that there is no association between Alzheimers
disease and stroke. Epidemiological studies in the 1980s and
early 1990s were focused on links between Alzheimers and
maternal age, head injury, education, and familial Downs
syndrome. Evidence for the association between AD andvascular
risk factors emerged in the late 1990s: the association
with smoking being particularly strong when industry-spon-
sored trials were removed from meta-analyses (7). Other risk
factors now appear very significant: type II diabetes,
midlife
obesity, and midlife exercise levels (8).
As a medical community, we need to be aggressively
managing all these factors as well as developing techniques
to address the divide between the acute stroke patient in
2010
and the dementia referral in 2015. We need to be able to
longitudinally examine what is happening to the brains of
people presenting both with stroke, and with vascular risk
factors, particularly thosewith carotid arterial disease and
type
II diabetes. In vivo, we need to harness brain imaging
tech-niques, both structural and functional, to interrogate the
relationship between brain volume, amyloid imaging, and
cognitive trajectory. Postmortem, we need to correlate our
observations with pathology, to fully understand the
incidence
and prevalence of vascular disease and AD pathology.
The epidemic is upon us, and raises both enormous challen-
ges and the potential for great progress. This will only
happen
if we develop a connection between the discourse of the
stroke patient of today and the cognitive clinic referral of
tomorrow.
References
1 Suh GH, Kee BS. Prevalence of dementia in Asia: report of
ASIADEM
collaborative studies.Alzheimers Demen2010; 6:S124.
2 Guerchet M, Houinato D, Mouanga AMet al. Risk factors for
dementia
in elderly living in three French-speaking African
countries.Alzheimers
Demen2010; 6:S124.
3 Alzheimers Disease International World Alzheimers Report.
London:
Alzheimers Disease International, 2009.
4 Ferri CP, Prince M, Brayne Cet al. Global prevalence of
dementia: a
Delphi consensus study.Lancet2005; 366:21127.
5 Mackay J, Mensah GA. The Atlas of Heart Disease and Stroke.
World
Health Organization, 2007.
6 Srikanth VK, Quinn SJ, Donnan GA, Saling MM, Thrift AG.
Long-term
cognitive transitions, rates of cognitive change, and predictors
of
incident dementia in a population-based first-ever stroke
cohort. Stroke2006; 37:247983.
7 Cataldo JK, Prochaska JJ, Glantz SA. Cigarette smoking is a
risk factor
for Alzheimers Disease: an analysis controlling for tobacco
industry
affiliation.J Alzheimers Dis2010; 19:46580.
8 Middleton LE, Yaffe K. Promising strategies for the prevention
of
dementia.Arch Neurol2009; 66:12105.
& 2010 The Authors.
International Journal of Stroke & 2010 World Stroke
Organization Vol 5, December 2010, 453454454
Leading opinions T. Cumming and A. Brodtmann
