Fig. 3.

Lithium specifically increases the volatility of positive affect in patients with BD. The volatility and noise of positive (A) and negative (C) affective ratings in patients from the BD group of the cohort study who were and were not receiving treatment with lithium are shown. The charts illustrate the mean (± SEM) of volatility and noise at day 50. Patients receiving lithium have a higher volatility of positive affect (panel A), with no effect on the noise of positive ratings or on either outcome for negative ratings (panels A and C). Although this result raises the possibility that lithium causes an increase in positive affective volatility, strong evidence for causality requires a randomized design. Panels B and D illustrate the results of a randomized trial of lithium, with the change in the volatility and noise of positive (B) and negative (D) affective ratings across the treatment period of the study shown. The charts illustrate the mean (± SEM) of the changes in volatility and noise at day 28 (relative to the end of the run-in period). As can be seen, the results of this randomized study are consistent with those from the cohort study, with lithium producing a specific increase in the volatility of positive affect ratings, with no effect on the other measures. Data from participants in the bipolar group of the cohort study who are being treated with lithium are summarized in red and those not taking lithium by orange bars. From the experimental medicine study, participants randomized to lithium are represented by yellow/orange and those to placebo by purple bars. Bars reporting volatility have dotted edges and those reporting noise have dashed edges.