A meta-analysis of neuropsychological functioning in first-episode bipolar disorders

Challenges and developments in research of the early stages of bipolar disorder

“…62,63 The nature of the control groups used in these first-episode studies is also a topic of some debate. 59,64 Findings that emerge from studies comparing BD cases with healthy controls or probands to their relatives have shown consistent differences in regard to cognition. However, the magnitude of these differences in cognitive functioning itself differs according to the choice of control group.…”

“…56 Different methodologies have been used in first-episode studies, and this must be taken into account when interpreting results from such investigations. [57][58][59] For instance, there is a lack of homogeneity regarding the definition of first mood episode. Follow-up studies have included patients with different mood states (mania, mixed states, or BD depression); included mixed samples of patients with BD and psychosis; or have defined first-episode onset as the first hospitalization.…”

“…Follow-up studies have included patients with different mood states (mania, mixed states, or BD depression); included mixed samples of patients with BD and psychosis; or have defined first-episode onset as the first hospitalization. 57,59 The mean age of the BD sample is another limitation in some studies. In our review of the literature, it is notable that most first-episode BD studies were conducted in adults 60,61 and very few included children or adolescents.…”

“…Overall, when compared to healthy controls, BD cases demonstrate more overt cognitive impairment, whereas smaller differences in cognitive performance have been observed when BD cases are compared to healthy relatives. 59 This may point to methodological issues, or may represent a genuine link between a clinical phenotype and an inherited endophenotype. 65 However, disentangling these issues is complex, as even first-episode studies include many patients on polypharmacotherapy, and the possible triggering effect of these drugs has not been considered.…”

“…65 However, disentangling these issues is complex, as even first-episode studies include many patients on polypharmacotherapy, and the possible triggering effect of these drugs has not been considered. 57,59 Prospective studies of individuals at clinical risk of BD Prospective studies of individuals at risk of BD present a potentially reliable and valid approach to understanding the progression of BD psychopathology. 4,66 Many studies use enrichment strategies to enhance the possibility of studying a sample in which a large proportion of subjects experience onset of BD.…”