Neurocognitive heterogeneity in young offspring of patients with bipolar disorder: The effect of putative clinical stages

Background: Bipolar disorder (BD) is associated with significant cognitive heterogeneity. In recent years, a number of studies have investigated cognitive subgroups in BD using data-driven methods and found that BD includes several subgroups including a severely impaired and a neurocognitively intact cluster. Studies in offspring of BD (BDoff) are particularly important to establish the timing of emergence of cognitive subgroups but studies investigating cognitive heterogeneity in BDoff are lacking. Our aim was to investigate cognitive heterogeneity in BDoff and the relationship between cognitive heterogeneity and putative clinical stages of BD. Methods: Seventy-one euthymic BDoff and 50 healthy controls were assessed using clinical measures and a battery of neuropsychological tests. Neurocognitive subgroups were investigated using latent class analysis. Results: Three neurocognitive subgroups, including a severe impairment group, a good performance cluster, and a subgroup characterized by intermediate/selective impairment was found. Both severe and intermediate level impairment subgroups underperformed healthy controls in processing speed, verbal fluency, visual memory and working memory. Deficits in verbal memory and executive functions were only evident in severe impairment subgroup. The putative stage of the illness had no significant effect on cognitive clustering of BDoff. Trait impulsivity scores were significantly increased in severe and intermediate impairment clusters but not in the cognitively good functioning subgroup of BDoff. Limitations: The cross-sectional nature of the study was the main consideration. Conclusion: These results suggest that cognitive heterogeneity is premorbid characteristic of BD and cognitive subgroups of BDoff emerge prior to the onset of illness and prodromal symptoms.