Brain structural effects of psychopharmacological treatment in bipolar disorder

Advances in magnetic resonance imaging (MRI) acquisition and analyses over the last two decades have enabled the identification of neuroanatomical abnormalities in a range of mental disorders, however one question which has consistently surfaced is the extent to which the medications used to treat such disorders may accentuate or ameliorate these abnormalities. Bipolar disorder causes substantial suffering and disability, but most patients can be successfully treated with mood stabilizing medication, such as lithium or valproate, and with antipsychotic or antidepressant medication during episodes of illness exacerbation. MRI studies comparing patients with bipolar disorder and healthy volunteers have demonstrated subtle grey matter volume deficits in patients, especially in brain regions underpinning mood regulation, as well as white matter disorganization in tracts interconnecting distributed brain regions. However studies tend to display considerable heterogeneity in their findings. In this review of in vivo neuroanatomical imaging studies of bipolar disorder to date, McDonald discusses the evidence that differential usage of psychopharmacological treatment is associated with alterations in neuroanatomy and thus an important source of this heterogeneity.