In 1991, investigators added patient weight to this annual assessment. According to Johnson, the scientific information available on weight loss in the elderly is sparse. Studies have suggested that weight generally begins a slow but steady decline of about half a pound per year in the late 50s and early 60s. Gerontologists have speculated that the decline may be attributable to physical shrinkage of the body seen in old age, loss of interest in eating or the wasting effects of cancers and other health factors.
The study analyzed data on 449 participants, most in their 70s and 80s but some as young as 65. All were cognitively normal at the beginning of the study but 125 were eventually diagnosed with mild dementia.
"Interestingly, the group of volunteers who did become demented started the study weighing about eight pounds less on average than the patients who did not develop dementia," Johnson notes. "The two groups lost weight at the same rate for four to five years, and then one year before the detection of even the mildest cognitive symptoms, weight loss increased in the group that would eventually be diagnosed with mild dementia."
It's unclear why the group that developed dementia began the study at a lower average weight. Johnson speculates that a process somehow related to Alzheimer's might have become active earlier in the participants' lives and started to drive their weight down. Alternatively, persons with lower average weight may be more vulnerable to Alzheimer's.
"No matter what we did to control for other health variables, such as diabetes, stroke and hypertension, none of them could account for this effect," Johnson says. "Sometime between the last evaluation when they were healthy and this first evaluation when they had mild dementia, a metabolic process kicked in, or kicked into higher gear, and made their Alzheimer's
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Contact: Michael C. Purdy
purdym@wustl.edu
314-286-0122
Washington University School of Medicine
11-Sep-2006