AHA/ASA Issue Scientific Statement on Vascular Dementia

From Medscape Education Clinical Briefs

News Author: Megan Brooks
CME Author: Désirée Lie, MD, MSEd

07/28/2011

Clinical Context

According to the current study by Gorelick and colleagues, by 2025 there will be 1.2 billion persons worldwide who will be 60 years and older. Also, in persons 80 years and older — a fast-growing population in developed countries — approximately 20% experience difficulties in activities of daily living, with cognitive impairment increasing in prevalence with age.
In addition, risk markers for stroke are now understood to be risk markers for Alzheimer's disease and other cognitive impairments. Vascular cognitive impairment (VCI) is a cause of microvascular brain damage, and arterial stiffness and atherosclerotic changes may be common risk factors for VCI.
This statement from the American Heart Association (AHA) and the American Stroke Association (ASA) describes vascular contributions to cognitive impairment and provides recommendations for prevention, treatment, and future research.

Study Synopsis and Perspective

Vascular changes are "important" contributors to cognitive impairment and dementia and should be routinely addressed in clinical practice, according to a new scientific statement from the AHA and ASA.
The 42-page statement, "Vascular Contributions to Cognitive Impairment and Dementia," was published online July 21 in Stroke and will appear in the September print issue of the journal.
The American Academy of Neurology and the Alzheimer's Association have endorsed the statement. The Alzheimer's Association participated in its development.
In comments to Medscape Medical News, Philip B. Gorelick, MD, MPH, cochair of the writing group for the statement and director of the Center for Stroke Research at the University of Illinois College of Medicine at Chicago, said vascular factors "have long been thought to be an important contributor to cognitive decline and dementia in later life."
Still, they have not received as much attention as Alzheimer's disease, "which has been on the center stage of scientific inquiry," he added.
 
Introducing 'Vascular Cognitive Impairment'
Dr. Gorelick and the writing group systematically reviewed published studies, guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and, when appropriate, offer recommendations for care.
"Over time and with careful study, vascular factors have been found to play a role in both vascular and so-called neurodegenerative forms of cognitive impairment such as Alzheimer disease," Dr. Gorelick said.
On the basis of the evidence, the writing group formally introduces the construct of "vascular cognitive impairment" (VCI). This, they say, captures "the entire spectrum of cognitive disorders associated with all forms of cerebral vascular brain injury — solely stroke — ranging from mild cognitive impairment through fully developed dementia.
"The neuropathology of cognitive impairment in later life is often a mixture of Alzheimer disease and microvascular brain damage," the study authors note, "which may overlap and synergize to heighten the risk of cognitive impairment."
In this regard, magnetic resonance imaging and other neuroimaging techniques "play an important role" in detecting and defining VCI, they advise.
 
What's Good for the Heart Is Good for the Brain
It is now "accepted," the team writes, that many of the traditional risk markers for heart disease and stroke are also risk markers for VCI and Alzheimer's disease.
"Stroke and heart disease are linked by a number of cardiovascular risk factors, such as hypertension, hypercholesterolemia, diet, tobacco exposure, and other factors," Dr. Gorelick explained.
"These vascular factors and others may play a causal role in the development of cognitive impairment and dementia in later life."
Carotid intimal-medial thickness and arterial stiffness are "emerging as markers of arterial aging and may serve as risk markers for VCI," the writing group points out.
Detection and control of the traditional risk factors for stroke and cardiovascular disease may help guard against VCI. "We encourage clinicians to use screening tools to detect cognitive impairment in their older patients and continue to treat vascular risks according to nationally- and regionally-accepted guidelines," the study authors write.
"At the very least," Dr. Gorelick said, screening for and treatment of vascular risk factors, including hypertension, hyperglycemia, and hypercholesterolemia, may reduce the occurrence of stroke and heart disease. "There may be an added benefit of prevention and treatment of vascular risk factors — the prevention of cognitive impairment and dementia in later life," he added.

Specifically, in persons at risk for VCI, the writing group concludes that

• Smoking cessation is reasonable (Class IIa; Level of Evidence A);
• Moderation of alcohol intake, weight control, and physical activity may be reasonable (all Class IIb; Level of Evidence B); and
• Use of antioxidants and B vitamins is not useful, based on current evidence (Class III; Level of Evidence A).

For individuals with vascular dementia, they conclude that

• Donepezil can be useful for cognitive enhancement (Class IIa; Level of Evidence A);
• Galantamine can be beneficial for individuals with mixed Alzheimer disease/vascular dementia (Class IIa; Level of Evidence A); and
• The benefits of rivastigmine and memantine are not well established in vascular dementia (Class IIb; Level of Evidence A).

The study authors also note that a Mediterranean-type dietary pattern has been associated with less cognitive decline in several studies and may be reasonable (Class IIb; Level of Evidence B).
Vitamin supplementation is not proven to improve cognitive function, even if homocysteine levels have been positively influenced, and its usefulness is not well established (Class IIb; Level of Evidence B). The effectiveness of antiaggregant therapy for VCI is not well established (Class IIb; Level of Evidence B).
Reached for comment, Thomas Russ, MD, PhD, from the University of Edinburgh, Scotland, said, "This is a clear outline of the difficulties surrounding the rather complicated overlap and interaction between vascular changes and the neuropathological changes of Alzheimer disease both resulting in cognitive impairment and dementia.
"The recommendations for prevention are a useful restatement of the current state of knowledge and a helpful reminder that we need to intervene sufficiently early in a condition which develops over the course of years and decades — ie, middle age," added Dr. Russ, who was not involved in the writing group.


Stroke. Published online July 21, 2011.