Accelerated Weight Loss May Signal Imminent Dementia Onset

http://www.medpagetoday.com/Neurology/AlzheimersDisease/tb/4081

Explain to interested patients that weight loss is a common feature of
advanced age, and that the findings of this study -- an association
between accelerated weight loss and the risk of dementia -- need to be
confirmed in larger studies.

Additional Alzheimer's Disease Coverage
Review
ST. LOUIS, Sept. 11 -- An early warning sign for Alzheimer's disease
could be accelerated weight loss, researchers here suggested.

Among more than 400 healthy older adults ages 65 to 95, followed as part
of a longitudinal study of Alzheimer's, those who had a sudden doubling
of the rate of weight loss developed dementia about a year later, found
David K. Johnson, Ph.D., of Washington University, and colleagues.

"Specific factors contributing to weight loss are unknown, but these
data suggest they operate before the development of dementia of
Alzheimer's type," the authors reported in the Sept. 11 issue of
Archives of Neurology. "Hence, weight loss may be a preclinical
indicator of Alzheimer disease."

Other studies have shown that weight loss is associated with development
of dementia and with nursing home placement, but the timing and rate of
the weight loss in relationship to the first signs of dementia are
unknown, the authors noted.

They looked at rates of weight change in 449 volunteers (192 men, 257
women), who were cognitively healthy at baseline. The volunteers were
controls in a longitudinal study of memory and aging.

Participants were weighed at study outset and at annual visits. The
investigators created piecewise linear regression and random effects
models to test longitudinal rates of weight change between the demented
and non-demented groups.

In all, 125 of the original cohort went on to develop Alzheimer's-type
dementia, and 324 remained cognitively healthy.

The investigators found that participants without dementia lost 0.65
(standard error, 0.13) pounds per year over the entire study period
(January 1991 to March 2005).

Weight loss in the group that went on to develop dementia was similar
(0.68 lbs per year, SE 0.27) until one year before the diagnosis of
dementia. At that time, "there was a sharp acceleration such that the
slope roughly doubled in magnitude."

In the year before the diagnosis, these participants lost 1.2 pounds,
double the rate of the non-demented patients.

They also found that participants in the dementia group weighed an
average of 8.2 lbs less at baseline than the participants whose mental
faculties remained intact at study end.

The association between accelerated weight loss and dementia held up
even when the investigators controlled for other factors potentially
associated with weight loss, such as age, gender, health status,
hypertension, and history of stroke.

The weight loss among patients with dementia was greatest when other
health factors such as cardiovascular symptoms, male gender, and poor
health were present, but these risks did not mediate the doubling of
weight loss, the authors wrote.

"Other health risks investigated (depressive symptoms, marital status,
use of potentially anorectic medications, APOE-4 expression, diabetes
mellitus, and appetite change) were not related to weight loss and
dementia progression," they added.

The findings from this and other epidemiologic studies suggest that
Alzheimer's disease may be preceded by two phases of weight loss, the
authors wrote.

"At midlife, participants who will eventually have dementia weigh as
much as their peers without dementia," they wrote. "At late midlife or
early late life, these individuals begin to lose weight at faster rates,
and by six years before dementia detection, participants who will
eventually develop dementia are six to eight pounds lighter on average."

"The present study shows that at least one year before dementia
detection, the rate of weight loss again increases. Thus, weight loss
associated with dementia of the Alzheimer's type probably begins very
early in the course of the disease and then accelerates in the one to
two years before the onset of cognitive symptoms," they wrote.