Vascular dementia, also known as multi-infarct dementia and vascular
cognitive impairment, is dementia caused by problems in the supply of blood to
the brain, typically by a series of minor strokes. Vascular dementia is the
second-most-common form of dementia after Alzheimer's disease in older
adults. Vascular dementia is thought to be irreversible and it is caused by a
number of small strokes or sometimes a large stroke preceded or followed by
other smaller strokes. The term refers to a group of syndromes caused by
different mechanisms all resulting in vascular lesions in the brain. Early
detection and accurate diagnosis are important, as vascular dementia is at
least partially preventable. Some main presenting signs of this
disease are: a single strategic infarct, multiple brain infarcts, haemorrhagic
lesions. Vascular lesions can be the result of
diffuse cerebrovascular disease, such as small vessel disease or focal lesions,
but usually both. Mixed dementia is diagnosed when patients have evidence of
Alzheimer's Dementia and cerebrovascular disease, either clinically or based on
neuro-imaging evidence of ischaemic lesions. In practice, vascular dementia
and Alzheimer's disease often coexist, especially in older patients.
Vascular dementia is sometimes triggered by cerebral amyloid angiopathy, which
involves accumulation of beta amyloid plaques in the walls of the cerebral
arteries, leading to breakdown and rupture of the vessels. Since amyloid
plaques are a characteristic feature of Alzheimer's Disease, vascular dementia
may occur as a consequence. However, cerebral amyloid angiopathy can also
appear in people with no prior dementia condition and some beta amyloid plaques
are often present in cognitively normal elderly persons.
Signs and symptoms Dementias present similarly to one
another and are very difficult to differentiate clinically, despite having
different organic causes. Patients suffering from vascular dementia present
with cognitive impairment, acutely or subacutely as in mild cognitive
impairment, after one or many cerebrovascular events. The symptoms of
dementia may progress gradually or step-wise after each small stroke. Some
people may appear to improve between events and decline after more silent
strokes. The incidence peaks between the fourth
and the seventh decades of life and 80% will have a history of hypertension.
Patients develop progressive cognitive, motor and behavioural signs and
symptoms. A significant proportion also develop affective symptoms. These
changes typically occur over a period of 5–10 years. If the frontal lobes are
affected, which is often the case, patients may present as apathetic or
abulic. This is often accompanied by problems with attention, orientation and
urinary incontinence. Although atheroma of the major cerebral arteries is
typical in vascular dementia, smaller vessels and arterioles are mainly
affected. Rare genetic disorders which result in
vascular lesions in the brain have other patterns of presentation. As a rule,
they tend to present earlier in life and have a more aggressive course. In
addition, infectious disorders such as syphilis lead to artery damage and
strokes along with bacterial inflammation of the brain.
Diagnosis Several specific diagnostic criteria can
be used to diagnose vascular dementia, including the Diagnostic and Statistical
Manual of Mental Disorders, Fourth Edition criteria, the International
Classification of Diseases, Tenth Edition criteria, the National Institute
of Neurological Disorders and Stroke- Association Internationale pour la
Recherche et l'Enseignement en Neurosciences criteria, the Alzheimer's
Disease Diagnostic and Treatment Center criteria, and the Hachinski ischemic
score. Lateralizing signs such as hemiparesis,
bradykinesia, hyperreflexia, extensor plantar reflexes, ataxia, pseudobulbar
palsy, and gait and swallowing difficulties may be observed.
Signs are typically the same as in other dementias, but mainly include cognitive
decline and memory impairment, sufficient severity as to interfere with
activities of daily living, presence of focal neurologic signs and evidence of
relevant features consistent with cerebrovascular disease on brain
imaging. Patients have patchy deficits in terms of cognitive testing. They tend
to have better free recall and fewer recall intrusions compared with patients
with Alzheimer's disease. In the more severe patients, or those patients
affected by strategic infarcts in Wernicke's or Broca's areas, dysarthrias
and aphasias may be present. In small vessel disease, the frontal
lobes are often affected. Apathy early in the disease is more suggestive of
vascular dementia because it usually occurs in the later stages of
Alzheimer's dementia. Consequently, patients with vascular dementia tend to
perform worse than their Alzheimer's disease counterparts in frontal lobe
tasks, such as verbal fluency. They also tend to exhibit more perseverative
behavior. They may also present with general slowing of processing ability,
difficulty shifting sets and impairment in abstract thinking.
The recommended investigations for cognitive impairment should be carried
out, including blood tests, chest X-Ray, ECG, and some type of neuroimaging,
preferably a scan with a functional or metabolic sensitivity beyond simple CT
or MRI. When available as a diagnostic tool, single photon emission computed
tomography and positron emission tomography neuroimaging may be used to
confirm a diagnosis of multi-infarct dementia in conjunction with evaluations
involving mental status examination. In a person already having dementia, SPECT
appears to be superior in differentiating multi-infarct dementia
from Alzheimer's disease, as compared with the usual attempts to differentiate
the dementing processes by employing mental testing and medical history
analysis. Advances have led to the proposal of new diagnostic criteria.
The screening blood test would typically include full blood count, liver function
tests, thyroid function tests, lipid profile, erythrocyte sedimentation rate,
C reactive protein, syphilis serology, calcium serum level, fasting glucose,
urea and electrolytes, vitamin B-12, folate. In selected patients HIV
serology and autoantibody testing may be done.
= Pathology and necropsy= Gross examination of the brain may
reveal noticeable lesions and artery damage. Accumulation of various
substances such as lipid deposits and clotted blood appear on microscopic
views. The white matter is most affected, with noticeable atrophy and
tissue loss, in addition to calcification of the arteries.
Microinfarcts may also be present in the gray matter, sometimes in large numbers.
On rare occasion, infarcts in the hippocampus or thalamus are the cause of
dementia. Cause
Risk factors for vascular dementia include age, hypertension, smoking,
hypercholesterolemia, diabetes mellitus, cardiovascular disease, and
cerebrovascular disease. Other risk factors include geographic
origin, genetic predisposition, and prior strokes. Further strokes must be
prevented through surgical or medical therapy to lessen the chance of
developing Multi-Infarct Dementia. Treatment
The goal of the management is the prevention of further cerebrovascular
lesions. This includes administering antiplatelet drugs and controlling major
vascular risk factors such as hypertension, hypercholesterolemia,
smoking and diabetes mellitus. The general management of dementia
includes referral to community services, judgment and decision-making regarding
legal and ethical issues, and consideration of caregiver stress.
Cholinesterase inhibitors such as galantamine have shown to be helpful in
various randomized controlled trials. However their use is not licensed yet
for this indication. Behavioral and affective symptoms are
particularly important in this patient group and deserve special consideration.
These problems, if they develop, tend to be resistant to conventional
psychopharmacological treatment and in many cases lead to hospital admission
and placement in permanent care. Prognosis
The 5-year survival rate is 39% for patients with vascular dementia compared
with 75% for age-matched controls. Unlike Alzheimer's Disease, which merely
weakens the victim to the point where they succumb to bacterial infections
like pneumonia, vascular dementia is a direct cause of death due to the
possibility of a fatal interruption in the brain's blood supply.
The prognosis for vascular dementia is usually not very promising. Symptoms may
begin suddenly with the onset of the disease and steadily become more
prevalent with each progressive small stroke. Even though it may seem that
people with vascular dementia improve over time, their condition often
steadily declines after ensuing silent strokes. A rapidly deteriorating
condition may lead to death from a stroke, heart disease, or infection.
Epidemiology Vascular dementia is the
second-most-common type of dementia in the United States and Europe in the
elderly, but it is the most common form in some parts of Asia. The prevalence of
the illness is 1.5% in Western countries and approximately 2.2% in Japan. It
accounts for 50% of all dementias in Japan, 20% to 40% in Europe and 15% in
Latin America. The incidence of dementia is 9 times higher in patients who have
had a stroke than in controls. 25% of stroke patients develop new-onset
dementia within 1 year of their stroke. The relative risk of incident dementia
is 5.5% within 4 years of suffering a stroke.
One study found that in the United States specifically, the prevalence of
vascular dementia in all individuals over the age of 71 is 2.43%, and another
found that the prevalence of the dementias doubles with every 5.1 years
of age. See also
Cerebrovascular accident Binswanger's disease
References External links
Helpguide article on vascular dementia J Bowler & V Hachinsky, Vascular
Cognitive Impairment: Preventable Dementia, Oxford University Press 2003,
ISBN 0-19-263267-1. Multi-Infarct Dementia Fact Sheet at
ninds.nih.gov Multi-Infarct Dementia at nmha.org
Vascular Dementia: Symptoms, Prognosis, and Support at helpguide.org
American Academy of Neurology. Walking And Moderate Exercise Help Prevent
Dementia. ScienceDaily. Retrieved December 21, 2007, from
www.sciencedaily.com2007071219202948.htm What is vascular dementia? Alzheimer's
Society fact sheet