Neurobiological Findings in Bipolar II Disorder Compared with Findings in Bipolar I Disorder

Abstract

While genetic data suggest there may be differences between BD II patients and BD I patients, the neurobiological findings to date do not provide support. However, this may be owing to the small number of studies directly comparing the 2 groups and also to the fact that those carried out have not been adequately powered to detect possible small true differences. This is an important issue because, if there are no neurobiological differences, it would be anticipated that similar treatments would be similarly effective in both groups. Given the importance of understanding whether there are neurochemical differences between these groups, further research in this area is clearly needed.

Fronto-Striatal Overactivation in Euthymic Bipolar Patients During an Emotional Go/NoGo Task

“…Likewise, no differences were observed when limiting analyses to those regions differentially activated by healthy comparison subjects and bipolar disorder patients. This is consistent with a recent literature review reporting that no significant anatomical or functional differences between these two subgroups could be inferred from the existing literature (39).…”

Anterior cingulate volumes associated with trait impulsivity in individuals with bipolar disorder

“…One previous study, using the Temperament and Character Inventory (47), suggested that patients with BPII had higher impulsivity than those with BPI. Therefore, the results of the current study may be confounded by BD subtype, although there was no significant difference in the BIS scores or ACC volumes between BPI and BPII patients, and little evidence for a neurobiological difference between BPI and BPII has been reported (48).…”

Neuronal Correlates of Brain-derived Neurotrophic Factor Val66Met Polymorphism and Morphometric Abnormalities in Bipolar Disorder

“…Our control markers, however, suggest that the Val/Met and Val/Val carriers are reasonably matched, as only one of the 18 control markers showed a statistical difference in genotypes between the Val/Met and Val/Val group, about what one would find by chance in two properly matched genetic samples. Regarding BD subtype, the results of this study may be confounded although there was no significant difference in ACC volumes between bipolar I and II patients and little evidence for a neurobiological difference between bipolar I and II has been reported (McGrath et al, 2004). Then, we did not evaluate the personality or character traits of the participants.…”