In a groundbreaking study that could change our understanding of how chronic diseases affect the ageing brain, researchers discovered that type 2 diabetes mellitus (T2DM) is strongly associated with cortical thinning in older adults, particularly in areas of the brain important for memory and cognition. 

The findings, published in Alzheimer's & Dementia: Diagnosis, Assessment, and Disease Monitoring, are the result of a comprehensive neuroimaging study conducted by the University of Southern California's Keck School of Medicine and Stevens Neuroimaging and Informatics Institute (INI). The University of North Texas Health Science Centre and the University of Texas in Austin are among the institutions that have collaborated. 

The researchers used advanced MRI scans to Health Disparities (HABS-HD) cohort, which is one of the most diverse brain health datasets in the United States. The study comprised Hispanic, non-Hispanic Black, and non-Hispanic white older . 

The researchers discovered that those with T2DM had much smaller cerebral cortexes, particularly in the temporal and parietal lobes, which are heavily implicated in memory processing and executive functioning. These structural brain abnormalities were shown regardless of other health problems such as obesity, hypertension, or dyslipidaemia, implying that T2DM has a direct role in brain degeneration. 

Crucially, the researchers identified poor glycaemic control, or the inability to adequately manage blood sugar levels, as a major factor in cortical thinning. 

"Since blood sugar levels can be managed with proper treatment and lifestyle interventions, our findings for protecting brain health through better diabetes management," said lead author Amaryllis A. Tsiknia, a PhD researcher at USC. 

The study's most remarkable finding was the variation in impact by ethnicity. Hispanic subjects had the highest correlation between T2DM and brain thinning, whereas non-Hispanic Black participants had no significant link. This ethnic disparity raises crucial concerns concerning how genetic, environmental, and socioeconomic factors interact in distinct groups. 

"The disparities we observed between ethnic and racial groups suggest that more work is needed to understand how exposures to various risk factors work together in distinct ways," said senior author Dr. Meredith N. Braskie, an assistant professor of neurology and co-leader of the HABS-HD project. "This is the first step care that best protects brain and cognitive health for each individual." 

Diabetes disproportionately affects Hispanic and Black communities in the United States, so our findings highlight the importance of public health initiatives geared to these populations. According to the CDC, Hispanic Americans are 70% more likely than non-Hispanic whites to be diagnosed with diabetes, a development that may have long-term cognitive implications. 

This study found that the cortical regions damaged by T2DM overlap with those known to be sensitive in Alzheimer's disease, raising concerns regarding accelerated cognitive ageing in diabetic populations. The researchers emphasise the importance of longitudinal studies to determine if cortical thinning accelerates cognitive decline or increases the risk of dementia. 

Dr. Arthur W. Toga, director of the Stevens INI and lead for neuroimaging in HABS-HD, emphasised the importance of large-scale, inclusive research initiatives like the HABS-HD. "This dataset — with its clinical assessments, MRI scans, lab tests, and cognitive exams — enables discoveries like this one, which can guide the future of neurological care in diverse communities," added the doctor. 

As type 2 diabetes continues to spread around the world, fuelled by sedentary lifestyles, poor diets, and ageing populations, the neurological repercussions highlighted by this study should act as ae-up call. Diabetes, long known for its effects on the heart, kidneys, and limbs, is now strongly linked to the slow decline of brain health. 

Effective blood sugar control achieved through medicine, nutrition, and physical activity may be more than just a physiological requirement but also a cognitive precaution. Researchers are exploring whether diabetic therapies could potentially slow or reverse these brain alterations, potentially revolutionising the fight against dementia.