Conflict monitoring and adaptation in individuals at familial risk for developing bipolar disorder.

Bipolar disorder is a highly heritable illness, with genetic influences explaining 60–85% of risk variance (1). However, specific susceptibility genes or neurobiological markers remain unknown. In recent years, genetic and behavioral neuroscience has attempted to define endophenotypes that encompass deficits that are heritable, state-independent, and cosegregated with illness, as well as those which occur at higher rates in unaffected relatives than the general population (2, 3). Plausible endophenotype candidates in bipolar disorder include impairments in specific neurocognitive domains. Cognitive impairments in individuals with bipolar disorder were traditionally thought of as mild and limited to acute mood episodes; however, a growing body of evidence challenges this assumption. At least three recent meta-analyses in euthymic adults with bipolar disorder (4–6) and two in youths with bipolar disorder have identified several cognitive impairments, particularly in attention, processing speed, and other aspects of executive function (7, 8). Some studies have suggested that medication exposure has an effect on cognition in both adult (9) and pediatric bipolar disorder subjects (10), while others have suggested no neurocognitive differences in euthymic unmedicated pediatric bipolar disorder subjects (11). Thus, studies of cognitive impairment in youths and adults with bipolar disorder cannot fully dissociate possible effects of illness chronicity and medication exposure. Studying youth at familial risk for developing bipolar disorder (i.e., with a parent who has bipolar disorder) could facilitate identifying cognitive endophenotypes, yet few studies have examined neurocognitive function in this population. Nonetheless, recent studies suggest that children of bipolar disorder patients demonstrate specific deficits in executive function, particularly in tasks assessing cognitive interference and flexibility (12, 13). Cognitive interference occurs when task-irrelevant background information impedes processing task-relevant information that forms the current focus of attention (14). Cognitive conflict may be best described as a special instance of cognitive interference in which task-irrelevant information induces incongruent or incompatible mental representations (15). Given this theoretical approach, selecting task-relevant over task-irrelevant information may be thought of as a core process in the resolution of cognitive interference, and the main goal of conflict monitoring (16). Similarly, changes in processing speed with shifting levels of conflict represent a measure of conflict-driven adaptation (17). In the current study, we examined conflict monitoring and conflict-driven adaptation in youths at risk for bipolar disorder using an arrow version of the Eriksen Flanker Task (EFT). We hypothesized that youths at risk for bipolar disorder would exhibit deficits in conflict monitoring and conflict-driven adaptation. Additionally, we predicted that youths at risk for developing bipolar disorder would be more susceptible to interference, exhibit increased behavioral inconsistencies as measured by increased variability of response time, and show less flexible cognitive adaptation to shifting levels of conflict than healthy controls.