Neuron somal size is decreased in the lateral amygdalar nucleus of subjects with bipolar disorder

Objective: Morphometric studies of postmortem brains from subjects with mood disorders have reported altered density of glial cells in the amygdala; however, the nuclear regions have not been examined individually. Methods: We assessed the size and density of both neuronal and glial cells in discrete amygdalar nuclei in postmortem sections from subjects with major depressive disorder, bipolar disorder (BD) and schizophrenia and from nonpsychiatric control subjects. Three adjacent Nissl-stained sections were examined from each individual. Results: We report significantly decreased neuron somal size in the lateral amygdalar nucleus (LAN) and the accessory basal parvocellular nucleus (ABPC) in subjects with BD, relative to control subjects. These changes in cellular morphology were most prominent in the LAN in sections obtained from the left hemisphere. Conclusions: These findings add to increasing evidence for neuropathological changes in the amygdala of subjects with BD and specifically implicate the LAN and ABPC in this disorder.