Hui TP, et al. - Researchers conducted this systematic review and meta-analysis to assess factors that could predict clinical response to lithium in bipolar disorder. Six predictors of good response were identified in a total of 71 studies, including over 12,000 patients: mania-depression-interval sequence, absence of rapid cycling, absence of psychotic symptoms, family history of bipolar disorder, shorter pre-lithium illness duration, and later age of onset. In two studies, poor response was linked to higher body mass index. Number of episodes prior to lithium therapy, the number of pre-lithium hospitalizations, and lithium response family history had weak connections. Due to potential biases and confounding, the relative importance of these clinical features should be interpreted cautiously.