Higher Insulin Levels Tied to Slower Decline in Early Alzheimer's
Last Updated: 2010-04-14 19:07:24 -0400 (Reuters Health)
TORONTO (Reuters Health) - In nondiabetic patients with Alzheimer's disease (AD), higher peripheral insulin levels are linked to slower cognitive decline and less brain atrophy, researchers reported today at the American Academy of Neurology's 62nd annual meeting.
Epidemiologic studies historically tied insulin resistance to risk of AD. However, Dr. Jeffrey Burns and associates at the University of Kansas School of Medicine, Kansas City, had previously found that higher insulin levels seemed linked to larger brain volumes and better cognition in patients who already had AD.
Their presentation today described a 2-year study of 44 patients with early-stage AD and 54 non-demented controls, all age 65 and older. The investigators followed these patients with structural magnetic resonance imaging studies, neuropsychological evaluations, and glucose tolerance tests.
With data controlled for age and sex, the insulin area-under-the-curve (AUC) was higher in AD patients compared with controls (p = 0.006).
In early AD, higher insulin levels were associated with less cognitive decline (p = 0.006) and less limbic atrophy (p = 0.01). An increase in insulin AUC by one standard deviation was associated with a 61% lower risk of rapid clinical progression, a 73% lower risk of rapid cognitive decline, and an 84% lower risk of rapid brain atrophy, Dr. Burns reported.
In controls, on the other hand, higher baseline insulin predicted more rapid global cognitive decline (p = 0.002), but not brain atrophy. In this group, and increase in insulin AUC by one standard deviation was associated with a 2.3-fold greater risk of preclinical AD.
These findings "suggest that insulin resistance is secondary to AD-related processes and may reflect a compensatory response to neurodegeneration," Dr. Burns said.
Alternatively, it may indicate a difference in underlying neuropathological processes, he added.
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