According to a new study, the younger age of type 2 diabetes is strongly related to an increased likelihood of developing dementia.
The researchers conducted a longitudinal cohort study with a mean follow-up time of 32 years. Data from the ages of 35 to 75 who experienced diabetes showed that any occurrence of diabetes five years earlier was significantly associated with a higher risk of dementia. At the age of 70, for example, the risk of dementia is 1.24 times higher with every five years earlier onset, according to Dr. Archana Singh-Manoux from Université de Paris and University College London and colleagues.
Remarkably, however, late-onset diabetes was not significantly associated with subsequent dementia. And in people with diabetes, stroke comorbidity was associated with an additional increased risk, the authors wrote.
There was also little evidence of a link between prediabetes and dementia. This could be because fasting glucose in the normal range doesn’t affect brain function, the authors suggested. In fact, according to the literature, fasting blood sugar is associated with little risk of vascular disease in people without diabetes.
“A certain threshold for high glucose levels may be required for brain injury caused by hyperglycemia,” wrote Singh-Manoux.
The mechanisms for the association between type 2 diabetes and dementia remain unclear, and previous studies have not always shown a consistent association between diabetes and Alzheimer’s traits such as amyloid and tau pathology.
“Taken together, these results underscore the importance of early diabetes age and cardiovascular comorbidity in people with diabetes for the risk of dementia,” they concluded.
The full results have been published in JAMA.
Clinical dementia type 2 diabetes