SA JOURNAL OF DIABETES & VASCULAR DISEASE
REVIEW
VOLUME 7 NUMBER 4 • NOVEMBER 2010
143
Cognitive decline: the relevance of diabetes,
hyperlipidaemia and hypertension
ThoRleIf eTgen, DIRk SAnDeR, hoRST BICkel,keRSTIn SAnDeR,hAnS föRSTl
Abstract
C
ognitive decline including mild cognitive impairment
describes a heterogeneous condition with cognitive
changes between normal ageing and dementia. Cog-
nitive impairment can be promoted or caused by treatable
somatic factors. In this review, three important cardiovascu-
lar risk factors, diabetes mellitus, hypercholesterolaemia and
hypertension, and their association with cognitive decline,
are assessed. Though there are many hints of a causal asso-
ciation between diabetes mellitus and the development of
cognitive decline, definitive proof of a protective effect of
antidiabetic treatment by controlled or randomised placebo-
controlled studies is needed. In midlife, elevated cholesterol
levels comprise a risk factor for cognitive decline. In elderly
subjects, cholesterol levels decline and are not clearly associ-
ated with cognitive impairment. The evidence for treatment
of hypercholesterolaemia by statins solely for prevention of
cognitive decline remains unclear. There is an age-dependent
relationship between blood pressure and cognitive impair-
ment. Midlife hypertension is associated with an increased
risk of developing cognitive decline and antihypertensive
treatment may therefore be beneficial, whereas hyperten-
sion later in life does not carry the same risk of cognitive
dysfunction. Diagnosis of these somatic factors is essential
in cognitive impairment, as diligent treatment may improve
cognitive performance and postpone the manifestation of
dementia.
Keywords:
cognitive impairment, dementia, diabetes, hyperlipi-
daemia, hypertension
Introduction
Cognitive decline includes mild cognitive impairment (MCI)
which is defined as cognitive impairment greater than expected
for an individual’s age and education level but that does not
interfere notably with activities of daily life. In contrast, dementia
is characterised by more severe and widespread cognitive deficits
that have a substantial effect on daily function.
1
MCI with memory
deficits (amnestic MCI) has a high risk of progression to dementia,
particularly of the Alzheimer type.
1
Incidence and prevalence of
different predementia syndromes including MCI vary as a result of
different diagnostic criteria, sampling, and assessment procedures.
According to recent epidemiological data, the prevalence of MCI
among the population aged
>
65 years in industrialised countries is
as high as 10–25%.
2,3
The progression rate from MCI into dementia
is estimated at about 5–10% per year.
4
Recent preventative strategies include the identification of risk
factors and predictors among patients with rapid cognitive decline
(MCI-plus).
5
As somatic co-morbidity often contributes to cognitive
decline and somatic risk factors are modifiable, the early detection
and treatment of these risk factors offers important opportunities
to delay and to avoid the manifestation of dementia.
6
This review considers the association of important cardio-
vascular risk factors, i.e. diabetes mellitus, hyperlipidaemia and
hypertension, with cognitive decline, as most studies did not
explicitly focus on MCI. Based on up-to-date references the value
of possible therapeutic interventions is discussed. These risk factors
contribute importantly to the modern concept of vascular cognitive
impairment, which incorporates the complex interactions between
vascular risk factors, cerebrovascular aetiologies and cellular
changes within the brain and cognition. While cerebrovascular
disease is preventable and treatable, it clearly is a major factor in
the prevalence of cognitive impairment in the elderly worldwide.
7
Correspondence to: Dr Thorleif Etgen
Department of Neurology, Klinikum Traunstein, Cuno-niggl-Strasse 3,
D-83278 Traunstein, Germany.
Tel: +49 (0)861 705 1771; fax: +49 (0)861 705 1515
e-mail:
T Etgen, H Bickel, H Förstl
Department of Psychiatry and Psychotherapy, Technische Universität
München, Munich, Germany.
D Sander, K Sander
Department of Neurology, Medical Park Loipl, Bischofswiesen, Germany;
Department of Neurology, Technische Universität München, Munich,
Germany.
S Afr J Diabetes Vasc Dis
2010;
7
: 143–148.
Abbreviations and acronyms
ACE
angiotensin-converting enzyme
ARB
angiotensin receptor blocker
BMI
body mass index
BP
blood pressure
CAIDe
Cardiovascular Risk factors, Aging and Dementia
CI
confidence interval
hPS
heart Protection Study
hR
hazard ratio
hYVeT-Cog hypertension Treatment in the Very elderly Cognitive
function assessment
MCI
mild cognitive impairment
MMSe
mini-mental state examination
MRC
Medical Research Council
MRI
magnetic resonance imaging
oR
odds ratio
PRogReSS Perindopril Protection Against Recurrent Stroke Study
PRoSPeR
Prospective Study of Pravastatin in the elderly at Risk
SCoPe
Study on Cognition and Prognosis in the elderly
SheP
Systolic hypertension in the elderly Program
Syst-eur
Systolic hypertension in europe
