Diabetes Linked to Brain Atrophy in Elderly Japanese

By Will Boggs MD

NEW YORK - Diabetes is associated with lower total brain and hippocampal volumes in elderly Japanese individuals, according to Hisayama Study investigators.

Diabetes appears to confer an increased risk of Alzheimer's disease, and hippocampal atrophy is a morphological feature of Alzheimer disease, but studies in Western countries have yielded conflicting results regarding the association between diabetes and hippocampal atrophy.

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Dr. Jun Hata from Kyushu University, Fukuoka, Japan and colleagues looked for associations between diabetes-related parameters and brain and hippocampal atrophy using MRI scans obtained from 1238 men and women age 65 and older.

The 286 individuals (23%) with diabetes had significantly lower mean values of all MRI parameters of brain atrophy compared with individuals without diabetes, after adjustment for age and sex.

Compared to subjects with normal glucose tolerance, people with diabetes had significantly lower average values of total brain-to-intracranial volume (an indicator of global brain atrophy), hippocampal-to-total brain volume (an indicator of hippocampal atrophy beyond global atrophy), and hippocampal-to-intracranial volume (an indicator of hippocampal atrophy).

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The same wasn't true for the groups with impaired fasting glucose or impaired glucose tolerance, however.

Elevated 2-hour postprandial glucose levels and longer duration of diabetes were significantly associated with lower mean values of all MRI ratios, according to the July 6th Diabetes Care online report.

Individuals with midlife diabetes had significantly greater hippocampal atrophy than did individuals without diabetes or those with late-life diabetes.

"Intriguingly," the researchers said, diabetics had significantly lower mean hippocampal-to-total brain volume ratios, "indicating not that hippocampal atrophy simply reflects global brain atrophy in subjects with diabetes but, rather, that the hippocampus is predominantly affected by diabetes."

These findings suggest "that the careful control of postprandial plasma glucose levels is important to prevent hippocampal atrophy and the subsequent development of dementia in individuals with diabetes," they conclude. "Further prospective cohort studies and experimental studies are needed to clarify the association between hyperglycemia and hippocampal atrophy."

Dr. Jacobus F. A. Jansen from Maastricht University Medical Center, The Netherlands recently reported on white matter interconnectivity and memory changes in type 2 diabetes. He told Reuters Health by email, "This study provides confirming evidence that the hippocampus is indeed more vulnerable to diabetes-induced alterations than other brain regions. It provides a convincing model for the link of diabetes with Alzheimer disease, due to the specific hippocampal atrophy."

"As diabetes seems to aggravate hippocampal atrophy, lifestyle interventions . . . seem relevant to halt or postpone the cerebral changes," Dr. Jansen concluded.

Dr. Hata did not respond to a request for comments.

SOURCE: http://bit.ly/29AMPDm

Diabetes Care 2016.

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