Bipolar disorders, obesity and antipsychotic treatment share a common pattern of widespread cortical thickness alterations – ENIGMA study in 2 443 individuals

COEX 

In this study, we applied principal component analyses and clustering to T1-weighted structural MRI data from 2443 participants with bipolar disorders (BD) and healthy controls and studied the associations between principal components and clinical and, demographic variables. The first principal component (PC) accounted for 42.7% of variance in cortical thickness across the whole brain and was associated with diagnosis of BD, BMI, treatment with antipsychotic medications and age. Lithium treatment was also associated with the first PC, but in opposite direction than the other factors. We could not find brain alterations specific to only a single system level variable. In other words, many different system level variables, were associated with cortical thickness in the same network of regions, a pattern reported also in other large studies. There appears to be a common common and difuse background of non-specific atrophy, which explains by far the largest proportion of variance across brain regions and is strongly associated with many different system level variables. This poses a significant challenge in our attempts to detect more specific brain signatures of specific pathologies.