Cognitive deficits are apparent in the early stages of bipolar disorder; however, the timing and trajectory of cognitive functioning following a first episode of mania remains unclear. The aim of this study was to assess the trajectory of cognitive functioning in people following a first episode of mania over a 12-month period, relative to healthy controls.

The cohort included 61 participants who had recently stabilised from a first treated manic episode, and 21 demographically similar healthy controls. These groups were compared on changes observed over time using an extensive cognitive battery, over a 12-month follow-up period.

A significant group by time interaction was observed in one measure of processing speed (Trail Making Test – part A,) and immediate verbal memory (Rey Auditory Verbal Learning Test – trial 1), with an improved performance in people following a first episode of mania relative to healthy controls. On the contrary, there was a significant group by time interaction observed on another processing speed task pertaining to focussed reaction time (Go/No-Go, missed go responses), with first episode of mania participants performing significantly slower in comparison with healthy controls. Furthermore, a significant group by time interaction was observed in inhibitory effortful control (Stroop effect), in which healthy controls showed an improvement over time relative to first episode of mania participants. There were no other significant interactions of group by time related to other measures of cognition over the 12-month period.

Our findings revealed cognitive change in processing speed, immediate memory and one measure of executive functioning over a 12-month period in first episode of mania participants relative to healthy controls. There was no evidence of change over time for all other cognitive domains. Further studies focussed on the at-risk period, subgroup analysis, and the effects of medication on the cognitive trajectory following first episode of mania are needed.