Type 2 Diabetes Linked to Accelerated Brain Cortical Thinning and Cognitive Decline: Study
USA: Researchers have found in a longitudinal study of cognitively healthy older adults that type 2 diabetes is associated with accelerated thinning of specific cortical brain regions over nearly three years. The effect was independent of Alzheimer’s disease pathology and cerebrovascular burden.
Adults with diabetes showed faster thinning in frontal, parietal, and occipital regions, including the superior frontal cortex, superior parietal lobule, precuneus, cuneus, lingual, and pericalcarine regions. Higher baseline HbA1c levels were also associated with greater cortical thinning.
Importantly, diabetes-related cortical thinning partially explained the faster decline in processing speed observed in individuals with T2D, accounting for approximately 13% of this cognitive effect.
The findings reinforce the importance of optimal glycemic and cardiovascular risk-factor control in diabetes and suggest that diabetes-related brain structural changes may contribute to accelerated brain aging and cognitive decline even before overt cognitive impairment develops.
The study, published in Brain, was led by Amaryllis A. Tsiknia of the University of Southern California in Los Angeles, CA, USA, and colleagues. The researchers sought to determine whether diabetes-related neurodegeneration follows specific regional patterns and whether Alzheimer’s disease or cerebrovascular pathology could explain these changes.
The analysis included 1,298 cognitively unimpaired older adults, with a mean age of 65 years. Of these, 305 participants had diabetes and 869 were women. All participants underwent brain MRI scans at baseline and follow-up, allowing investigators to assess changes in cortical thickness across 34 brain regions over nearly three years.
Using statistical models, the researchers examined associations between diabetes and changes in cortical thickness while accounting for socioeconomic factors and other health conditions. They subsequently adjusted the analysis for amyloid and tau accumulation measured through PET imaging, white matter hyperintensity burden, and APOE ε4 carrier status.
The study led to the following findings:
- Participants with diabetes showed significantly faster cortical thinning in seven frontal, parietal, and occipital brain regions, independent of Alzheimer’s pathology, cerebrovascular changes, socioeconomic factors, comorbidities, and APOE ε4 status.
- Higher baseline HbA1c levels were linked to faster cortical thinning in diabetes-vulnerable brain regions, regardless of subsequent changes in HbA1c levels.
- Diabetes was associated with a faster decline in processing speed, with diabetes-related cortical thinning accounting for approximately 13% of this cognitive decline.
According to the investigators, the findings indicate that diabetes-related brain changes may develop in a region-specific manner rather than appearing as generalized brain atrophy. The absence of a clear dependence on Alzheimer’s or cerebrovascular pathology further suggests that diabetes itself, potentially through chronic hyperglycemia and related metabolic mechanisms, may contribute to neurodegeneration.
The study highlights the importance of maintaining appropriate glucose levels and managing cardiovascular risk factors in older adults with diabetes, potentially helping preserve brain health before measurable cognitive impairment becomes apparent.
Reference:
Tsiknia, A. A., Tennant, V. R., Davison, M., Nandy, R., Borzage, M., Clark, A. L., Toga, A. W., Yaffe, K., & Braskie, M. N. Diabetes and neurodegeneration in cognitively unimpaired older adults: Implications for cognition. Brain. https://doi.org/10.1093/brain/awag287
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