Is type 2 diabetes mellitus a risk factor for neuroanatomical changes, cognitive impairment and oxidative stress in bipolar disorders?

Bipolar disorder (BD) is a severe mental illness affecting tens of thousands of Canadians. It is the 6th most important cause of disability according to the World Health Organization. Some, but not all patients with BD show brain damage and memory impairment. Yet, the factors, which underlie these changes and the reason why they occur only in some patients with BD remain unknown. Type 2 diabetes mellitus (T2DM) damages the brain, impairs memory and frequently co-occurs with BD. Perhaps the presence of T2DM in patients with BD contributes to the brain changes and memory impairment found in this disorder. Yet, no studies have directly looked at whether some of the brain changes and memory impairments observed in BD are related to the presence of comorbid T2DM. We propose to collect brain scans, memory tests and blood samples from 55 participants with BD+T2DM, 55 BD subjects without T2DM, 55 diabetic controls without BD and 55 healthy controls without BD or T2DM. The brain imaging will allow us to identify subtle differences between the groups in brain structure and chemical composition. We will investigate whether T2DM underlies some of the brain changes and cognitive impairments found in BD. The blood samples will allow us to study possible factors contributing to the brain and memory alterations. This study will provide a greater understanding of why not all, but only some persons with BD show brain changes and memory impairment. Identification of T2DM as a risk factor for brain and memory alterations in BD would be the first step towards their prevention. It could improve the unfortunately low standards of diabetes care in BD and may suggest novel treatment options. The negative economic and quality of life impact of BD makes attempts to better understand the factors associated with the poor memory functioning in some subjects with BD of paramount importance not only to patients and their families, but also to general public.