Scientists have demonstrated that normal brain ageing is accelerated by approximately 26 per cent in people with progressive Type 2 diabetes compared with individuals without the disease, according to a study. There is already strong evidence linking Type 2 diabetes with cognitive decline, yet few patients currently undergo a comprehensive cognitive assessment as part of their clinical care. The results, published today in eLife, suggest that by the time Type 2 diabetes is formally diagnosed, there may already be significant structural damage to the brain. The findings also suggest that the patterns of Type 2 diabetes-related neurodegeneration strongly overlap with those of normal ageing, but that neurodegeneration is accelerated. Sensitive ways to detect diabetes-associated changes to the brain are therefore urgently needed.
"Routine clinical assessments for diagnosing diabetes typically focus on blood glucose, insulin levels and body mass percentage," said Botond Antal, a doctoral student at the Department of Biomedical Engineering, Stony Brook University, US. "However, the neurological effects of Type 2 diabetes may reveal themselves many years before they can be detected by standard measures, so by the time Type 2 diabetes is diagnosed by conventional tests, patients may have already sustained irreversible brain damage," Antal added. The team evaluated the relationship between typical brain ageing and that seen in Type 2 diabetes from a dataset, which includes brain scans and brain function measurements, of 20,000 people aged 50 to 80 years old. The results were then compared with a meta-analysis of nearly 100 other studies. Their analysis showed that both ageing and Type 2 diabetes cause changes in executive functions such as working memory, learning and flexible thinking, and changes in brain processing speed. However, people with diabetes had a further 13.1 per cent decrease in executive function beyond age-related effects, and their processing speed decreased by a further 6.7 per cent compared to people of the same age without diabetes.
Further, MRI scans of people with and without diabetes showed that people with diabetes had even more pronounced decreases in gray matter beyond the typical age-related effects -- a further 6.2 per cent decrease in grey matter in the ventral striatum, but also loss of grey matter in other regions, compared with normal ageing. "Our findings suggest that Type 2 diabetes and its progression may be associated with accelerated brain ageing, potentially due to compromised energy availability causing significant changes to brain structure and function," said Lilianne Mujica-Parodi, at the varsity's Director of the Laboratory for Computational Neurodiagnostics. "By the time diabetes is formally diagnosed, this damage may already have occurred. Our results underscore the need for research into brain-based biomarkers for Type 2 diabetes and treatment strategies that specifically target its neurocognitive effects," Mujica-Parodi noted.