Insulin resistance, type 2 diabetes mellitus and future brain, cognitive, biochemical and clinical outcomes in bipolar disorders - prospective study

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 persons with BD show poor clinical outcomes, brain, biochemical changes and memory impairment. Yet, the factors, which underlie these changes and the reason why they occur only in some participants with BD remain unknown. Type 2 diabetes mellitus (T2D) damages the brain, impairs memory and frequently co-occurs with BD. Perhaps the presence of T2D could explain the poor outcomes in some BD participants. Yet, no studies have directly looked at whether T2D contributes to future brain, memory, biochemical and clinical impairments in BD. We propose to collect brain scans, memory tests and blood samples from 96 BD and 96 control participants at two time points, six years apart. This will allow us to study the changes in brain structure, chemical composition, memory function, clinical outcomes over time and the extent to which the presence of diabetes at baseline accelerates future worsening of these indices in BD or control participants. 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, memory impairment and worse clinical outcomes. Identification of T2D as a risk factor for biological and clinical changes 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 brain health, memory deterioration and worse clinical outcomes in some subjects with BD of paramount importance not only to patients and their families, but also to general public.