Insulin resistance and hippocampal volume in women at risk for Alzheimer's disease.
Level 4 - case-series / case-control
Cross-sectional observational analysis within a cohort study
PubMed 20031276 · doi:10.1016/j.neurobiolaging.2009.12.005
What was done
Fifty cognitively intact, non-diabetic postmenopausal women aged 50–65 who were current hormone therapy users and at risk for Alzheimer's disease underwent brain magnetic resonance imaging, cognitive testing (verbal and non-verbal memory), and fasting homeostatic model assessment of insulin resistance (HOMA-IR).
What was found
HOMA-IR had a significant negative relationship with right and total hippocampal volume, overall cognitive performance, and selective tests of verbal and non-verbal memory. The association was not modified by APOE-ε4 carrier status or reproductive history (duration of endogenous and exogenous estrogen exposure). The abstract reports no exact numerical values, correlation coefficients, or p-values.
Why it matters
The findings link peripheral insulin resistance to structural hippocampal differences and memory variation prior to clinical diabetes or dementia, indicating insulin resistance may serve as an early biomarker or intervention target in individuals at risk for Alzheimer's disease.
Limits
The sample size is small (n = 50), and the study population is limited to postmenopausal women taking hormone therapy, restricting generalizability to men or non-users of hormone therapy. The reported analysis is cross-sectional, preventing causal inference, and no quantitative effect sizes are provided in the abstract.
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