Type 2 diabetes is recognized as a significant risk factor for cognitive decline, potentially doubling the likelihood of an individual developing dementia. A comprehensive study involving over 31,000 individuals aged 40 to 70 has now established a correlation between type 2 diabetes and prediabetes with an accelerated rate of brain aging. However, the research also underscores the positive impact of physical activity, smoking cessation, and moderate alcohol consumption on maintaining youthful brain health.

"An older brain appearance relative to one's chronological age may signal a deviation from the normative aging trajectory and could serve as an early indicator of dementia," stated the principal investigator, Abigail Dove, affiliated with the Aging Research Center at the Karolinska Institute in Sweden. "Encouragingly, it appears that individuals with diabetes can exert influence over their brain health through a healthy lifestyle."

The investigation analyzed medical data from more than 31,000 adults without dementia from the UK Biobank. This data encompassed assessments of cardiometabolic risk factors, such as obesity, high blood pressure, and cholesterol levels, as well as lifestyle factors including smoking, alcohol consumption, and physical activity levels. Among the participants, 53% exhibited normal blood glucose levels, 43% were prediabetic, and 4% had type 2 diabetes.

Employing a machine learning algorithm, the researchers were capable of estimating the brain's age relative to a participant's chronological age. The study's findings, published in the journal Diabetes Care, revealed that individuals with type 2 diabetes had brains that appeared 2.3 years older than their actual age, while those with prediabetes showed a brain age advancement of approximately four months.

Further analysis of a subset consisting of around 2,400 patients who underwent MRI scans up to two times over an 11-year period indicated a slight but consistent annual increase in brain aging for those with diabetes, amounting to just over three months per year.

"The study demonstrates that even marginally elevated blood sugar levels, not high enough to be classified as diabetes but consistent with prediabetic conditions, can impact the brain and expedite the aging process," commented Susan Elizabeth Spratt, MD, a professor of medicine at Duke University, North Carolina, specializing in endocrinology, metabolism, and nutrition, who was not part of the study.

MRI technology provided detailed measurements such as brain volume, the thickness of the cortex (the brain's outer layer of nerve cell tissue, also known as gray matter), and the deterioration of white matter (the brain's network of nerve fibers). While MRIs offer valuable insights for research purposes, they may not be practical for routine cognitive assessment, according to Ajaykumar D. Rao, MD, head of the endocrinology, diabetes, and metabolism section at the Lewis Katz School of Medicine at Temple University, who was not involved in the study.

"We cannot subject all prediabetic and diabetic individuals to multiple MRIs — they may not be clinically meaningful," said Dr. Rao. "It's crucial for these patients to consult with their primary care providers to discuss the possibility of neurocognitive testing."

On a positive note, the study's authors discovered that certain lifestyle habits can significantly mitigate the risk of rapid brain aging. "The encouraging news is that embracing a healthy lifestyle — abstaining from smoking, limiting alcohol intake to no more than 14 drinks per week, and engaging in physical activity at least twice the current recommendations — can safeguard the brain from premature aging," said Dr. Spratt. The Centers for Disease Control and Prevention advises 150 minutes of moderate-intensity or 75 minutes of vigorous physical activity per week.

For Thomas Vidic, MD, an adjunct clinical professor of neurology at Indiana University School of Medicine and a practicing physician, the findings were not unexpected. "Diabetes leads to vascular disease and inflammation, which can affect blood flow to the brain and brain tissue. Conversely, exercise can enhance cerebral blood flow," he explained. "Furthermore, alcohol and smoking are detrimental to brain cells, while their avoidance can offer protection."

"Brain health is a lifelong journey, and it's imperative to nurture all facets of brain health throughout one's life," Dr. Vidic emphasized. "It's not something you start focusing on once you reach 65 and think, 'Now I need to begin taking care of this.'"