People with type 1 diabetes are at a higher risk of developing dementia, according to a study published March 18 in Neurology, the medical journal of the American Academy of Neurology. The research also found that people with type 2 diabetes face an increased risk compared to those without diabetes. The study shows an association but does not prove that diabetes causes dementia.
The findings are important as advances in medical care have extended the lives of people with type 1 diabetes, making it increasingly necessary to understand how the condition may affect long-term brain health. Type 1 diabetes is rare and accounts for about five percent of all diabetes cases.
"As advances in medical care have extended the lives of people with type 1 diabetes, it's becoming increasingly important to understand the relation of type 1 diabetes to the risk of dementia," said Jennifer Weuve, MPH, ScD, of Boston University. "We have known that type 2 diabetes is linked to an increased risk of dementia, but this new research suggests that, unfortunately, the association may be even stronger for those with type 1 diabetes."
The study included more than 283,000 participants with an average age of 64. Of these individuals, over five thousand had type 1 diabetes and more than fifty-one thousand had type 2 diabetes. Participants were followed for an average period of just over two years. During this time frame, nearly two thousand four hundred developed dementia: about three percent among those with type 1 diabetes; almost two percent among those with type 2; and less than one percent among those without any form of diabetes.
After adjusting for factors such as age and education level, researchers estimated that people with type 1 diabetes were nearly three times as likely to develop dementia as those without any form of the disease. For people with type 2 diabetes, the likelihood was twice as high compared to non-diabetics. Weuve said that roughly sixty-five percent of dementia cases among people with type 1 could be attributed directly to their condition.
"Type 1 diabetes is not common, so this condition accounts for a small fraction of all dementia cases. But for the growing number of people with type 1 diabetes who are over sixty-five years old, these findings underscore the urgency of understanding the ways in which type 1 diabetes influences dementia risk and how we can prevent or delay it," Weuve said.
A limitation noted by researchers is that both conditions were identified using electronic health records and survey data rather than clinical diagnoses in every case. The study received support from the National Institutes of Health.
