Cell pathology in mood disorders.

In new, exciting, neuroanatomic studies on postmortem tissues from patients with mood disorders, quantitative cytomorphologic differences can be shown at the microscopic level. These investigations provide direct evidence that mood disorders are characterized by marked reductions in glial cell number and density in addition to subtle alterations in the density and size of cortical neurons in frontolimbic brain regions. Importantly, this corresponds with clinical neuroimaging studies and preclinical animal studies that suggest cell atrophy, cell loss, or impairments in neuroplasticity and cellular resilience may underlie the neurobiology of major depressive disorder and bipolar manic-depressive disorder. Because this represents a departure from modern efforts to understand mood disorders, published reports are scarce and based on rather small sample sizes. This article reviews the current findings from postmortem studies on glial and neuronal cell counts in primary mood disorders and discusses a possible link between cellular changes and the action of psychotherapeutic drugs.