Summary: A new multi-institutional study finds that type 2 diabetes (T2DM) is linked to thinning of the brain’s cortex in older adults, especially in regions that support memory and cognition. Using advanced neuroimaging on a diverse cohort, researchers report that poorer blood sugar control—measured by higher hemoglobin A1c (HbA1c)—appears to drive these structural changes. The effect was most pronounced among Hispanic participants, highlighting both a public health concern and the potential for targeted interventions to preserve cognitive health.
The study underscores the importance of effective glycemic management in older adults and suggests that better diabetes control may help protect brain structure and function as people age.
Key Facts:
- Brain impact: Type 2 diabetes is associated with reduced cortical thickness in regions critical for cognition and memory.
- Glycemic control matters: Higher HbA1c levels were associated with thinner cortex in both people with and without diagnosed diabetes, indicating hyperglycemia as a likely driver.
- Disparities across groups: Associations were strongest and most widespread in Hispanic participants, more limited in non-Hispanic White participants, and not observed in non-Hispanic Black participants.
Source: USC
Overview of the study
Led by investigators at the Keck School of Medicine of USC’s Mark and Mary Stevens Neuroimaging and Informatics Institute (Stevens INI), in collaboration with the University of North Texas Health Science Center and the University of Texas at Austin, this study analyzed brain magnetic resonance imaging (MRI) data from the Health and Aging Brain Study-Health Disparities (HABS-HD) cohort. The research, published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring, examined relationships between T2DM, glycemic measures, and structural brain markers in cognitively normal older adults across diverse ethnoracial groups.
Type 2 diabetes affects roughly one in ten Americans and is associated with vascular, metabolic, and inflammatory processes that can harm multiple organ systems, including the brain. In this analysis of 2,171 cognitively unimpaired older adults, researchers measured cortical thickness across the cerebral cortex and hippocampal volume to determine whether T2DM or markers of glycemic control were linked to subtle structural brain changes that could presage cognitive decline.
The investigators found that older adults with T2DM had significantly thinner cortex, particularly in temporal and parietal regions that are important for memory and higher cognitive functions. Crucially, the association between diabetes and cortical thinning remained after adjusting for socioeconomic status and common comorbidities, including hypertension, dyslipidemia, and obesity.
Analyses showed that higher HbA1c—a long-term measure of blood glucose—was strongly associated with cortical thinning both in participants with diagnosed diabetes and in those without a diabetes diagnosis. This pattern supports the interpretation that hyperglycemia itself contributes to cortical atrophy rather than other features of diabetes alone.
The study’s ethnoracially diverse sample revealed important differences across groups. Hispanic participants displayed the most widespread and robust T2DM–cortical thickness associations. Non-Hispanic White participants showed more modest effects, mainly in temporal regions, while non-Hispanic Black participants did not show significant associations in this dataset. These findings point to variation in how risk factors and exposures may combine to affect brain health across communities.
“Because blood sugar can be managed through treatment and lifestyle change, our results emphasize the potential to protect brain health by improving diabetes care,” said Amaryllis A. Tsiknia, the PhD student who led the study. Senior author Meredith N. Braskie, PhD, noted that understanding these group-specific patterns is an essential step toward personalized strategies that safeguard cognition for each individual.
The research team calls for longitudinal follow-up to determine whether the observed cortical thinning translates into faster cognitive decline over time. They also recommend further studies to evaluate whether diabetes medications, intensive glycemic control, or lifestyle interventions can slow or prevent structural brain changes in people with elevated blood glucose.
This work highlights the value of large-scale, diverse research initiatives like HABS-HD, which collect clinical, imaging, cognitive, and biomarker data to advance understanding of Alzheimer’s disease, related dementias, and factors that influence brain aging.
Funding for the study came from the National Institutes of Health (S10OD032285) and the National Institute on Aging (R01AG054073, R01AG058533, R01AG070862, P41EB015922, U19AG078109).
Authors include Amaryllis A. Tsiknia, MSc; Victoria Tennant, BA; Noelle Lee, BA; Brandon J. Hall, MSc; Raul Vintimilla, MD; Nalini Hazra, MSc; Deydeep Kothapalli, MSc; Arthur W. Toga, PhD; Sid E. O’Bryant, PhD; Rajesh Nandy, PhD; Alexandra L. Clark, PhD; Melissa Petersen, PhD; Kristine Yaffe, MD; and Meredith N. Braskie, PhD.
About this neurology and diabetes research news
Author: Laura LeBlanc
Source: USC
Contact: Laura LeBlanc – USC
Image: The image is credited to Neuroscience News
Original Research: Open access. “Diabetes and cortical thickness in ethnically diverse cognitively normal older adults” by Amaryllis A. Tsiknia et al., published in Alzheimer’s & Dementia: Diagnosis, Assessment & Disease Monitoring.
Abstract
Diabetes and cortical thickness in ethnically diverse cognitively normal older adults
INTRODUCTION
Mechanisms connecting type 2 diabetes mellitus (T2DM) and dementia remain incompletely understood. This study examined associations between T2DM and two structural brain measures—cortical thickness and hippocampal volume—in an ethnoracially diverse group of cognitively normal older adults.
METHODS
Among 2,171 cognitively unimpaired older adults, the team evaluated: (1) how T2DM related to cortical thickness and hippocampal volume; (2) whether associations persisted after accounting for socioeconomic factors and comorbid conditions; (3) whether associations were driven by hyperglycemia (higher HbA1c) or hyperinsulinemia; and (4) whether associations differed by self-reported race/ethnicity.
RESULTS
T2DM correlated with thinner cortex independent of socioeconomic factors and common comorbidities, and this relationship appeared driven by higher HbA1c. Elevated HbA1c was linked to thinner cortex in both diabetic and non-diabetic participants. Effects were strongest and widespread among Hispanic participants, modest and regionally limited in non-Hispanic White participants, and not observed in non-Hispanic Black participants.
DISCUSSION
The findings indicate that type 2 diabetes is associated with reduced cortical thickness in older adults and that poor glycemic control contributes substantially to this association. These results support prioritizing blood sugar management as a potential strategy to protect brain health with aging.