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Alzheimer’s pathology reduced with combined diabetes therapy

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – In a postmortem study of patients with Alzheimer’s disease, diabetic subjects treated with both insulin and oral hypoglycemic agents had lower neuritic plaque densities than did other diabetics and nondiabetics, new research shows.

In several studies, type 2 diabetes has been identified as a risk factor for Alzheimer’s disease. The link between diabetes and Alzheimer’s neuropathology, by contrast, is less clear, according to the report in the September 2nd issue of Neurology.

The current study, conducted by Dr. M. S. Beeri, from Mount Sinai School of Medicine in New York, and colleagues involved an analysis of neuritic plaques and neurofibrillary tangles in brain specimens from 124 diabetics and 124 nondiabetics.

The diabetic group consisted of 29 patients who had never used antidiabetic agents, 49 who had received insulin only, 28 treated with agents other than insulin, and 18 treated with both insulin and oral antidiabetic mediations.

The overall neuritic plaque rating, the rating in the entorhinal cortex and amygdala, and the neuritic plaque count in all regions examined, differed significantly among the groups. In all of the analyses, the combined medication group had fewer neuritic plaques than did the other groups.

By contrast, the authors found no significant difference in neurofibrillary tangles between the groups.

The findings provide “evidence of substantially lower neuritic plaque density in diabetic subjects taking both insulin and hypoglycemic medication consistent with the effects of both on the neurobiology of insulin,” the researchers conclude. “These pathways should be considered as potentially mechanistically important in the etiology of amyloid-beta associated neuropathology and deposition of neuritic plaques.”

Neurology 2008;71:750-757.