The UC Davis Alzheimer’s
Disease Center has started a new research program that
will address scientific interests in three related themes:
mild cognitive decline associated with aging, effects
of cerebrovascular disease, and cross-cultural studies
of aging and cognitive impairment.
There is broad scientific interest in mild cognitive changes
that might be early indicators of progressive dementias
like Alzheimer’s disease. Early diagnosis and treatment
will be increasingly important as effective disease modifying
medications become available. There is increasing evidence
that isolated memory impairment is associated with an
elevated risk of developing Alzheimer’s disease.
A syndrome labeled “mild cognitive impairment”
has been identified, and several studies have shown that
patients with this syndrome develop clinical dementia
at a rate of 10% to 15% per year. However, diseases other
than Alzheimer’s disease also can cause mild cognitive
changes including memory impairment, and it is not well
know at this time if cognitive impairment resulting from
these other diseases will progress.
Cerebrovascular disease, in particular, is a very common
problem in older patients, and many consider it to be
the second most important cause of cognitive impairment
and dementia after Alzheimer’s disease. It is not
clear if, and at what rate, cognitive deficits caused
by cerebrovascular disease will progress to clinical dementia.
Another important issue is that much of the research on
Mild Cognitive Impairment has been performed with samples
from academic dementia clinics that include relatively
well-educated individuals, few of whom are from minority
populations, and it is not clear if results from these
studies will apply to older minority patients. Cerebrovascular
disease is particularly common in some minority groups,
African Americans and Latinos especially, and this raises
questions about whether mild cognitive problems in these
groups will have different causes and clinical significance.
All of these considerations converge and underlie our
interest in new studies to address several important questions:
1) Are there different profiles of mild cognitive decline
that are more and less likelyto progress to dementia,
2) Is cerebrovascular disease associated with particular
profiles of cognitive impairment and with progression
to dementia, and 3) Are there ethnic differences in profiles
of cognitive impairment and in progression from mild changes
to dementia. Studies to address these questions require
a large cohort of research participants from different
ethnic groups who are willing to undergo thorough clinical
evaluations and return for yearly follow-up.
In 2001, we started to recruit volunteers for this research
cohort. Our recruitment is targeted to include individuals
with normal cognitive function, mild impairment, and dementia.
We are trying to identify and recruit persons who have
no significant cerebrovascular disease and patients with
cerebrovascular disease that varies from mild to severe.
We also are targeting three ethnic groups, African Americans,
Latinos, and Caucasians. There are several sources of
recruitment.
We are working collaboratively with the Martinez Veterans
Administration Medical Center and with San Joaquin General
Hospital in Stockton to identify patients in these health
systems who are interested in participating in our research
program. An important aspect of this study is that we
are interested in the full range of cognitive function.
Many participants will be normal, and cognitive impairment
or dementia is not a requirement to be part of the study.
We are also recruiting from the community of Woodland
and from outreach activities in the Sacramento area and
the East San Francisco bay area. Those who agree to participate
are initially tested with a battery of neuropsychological
tests of memory and other abilities that has English-
and Spanish-language versions. These test results are
used to identify individuals who meet entry criteria for
our longitudinal study. These individuals are then invited
to come to our Center for a complete clinical evaluation
that includes a physical and neurological exam and a research
MRI scan. Those who continue to meet study criteria and
agree are enrolled in our longitudinal follow-up program
and will have neuropsychological tests and the clinical
examination repeated every year. These volunteers are
also invited to sign up for our brain donation program
to contribute to scientific study of how pathological
changes in the brain relate to cognitive decline. This
research program is intended to support a broad range
of studies to clarify diseases of aging that lead to cognitive
decline in ethnically diverse older people.
There currently are two research
projects that are independently funded by the National
Institute on Aging that are closely linked with this developing
research cohort. The first is a ten-year old grant led
by Dan Mungas, Ph.D. that has developed the neuropsychological
tests being used to identify and track cognitive change
in the different ethnic groups. This project will examine
patterns of cognitive change across ethnic groups and
usefulness of these patterns for predicting subsequent
cognitive decline. The second grant, led by Charles DeCarli,
M.D., was just recently funded and will examine how cerebrovascular
disease relates to mild cognitive impairment and subsequent
cognitive decline.
These grants utilize the patient sample and clinical infrastructure
supported by the UC Davis Alzheimer’s Disease Center,
but also contribute important neuropsychological assessment
and structural neuroimaging methods that will be used
in characterizing the cases in this sample. This sample
will serve as an important resource for future grant applications
to address important scientific questions as well as research
studies conducted by other investigators.
