The Mechanism of Drug-induced Akathsia.

Akathisia is a movement disorder characterized by an inner sense of unease, unrest, and dysphoria. It can result in an inability to stand, sit, or lie still, and an intense urge to move around. It is a common side effect of drugs, such as antipsychotics and serotonin selective reuptake inhibitors (SSRIs), but it also occurs spontaneously in patients with Parkinson's disease. Several lines of evidence suggest that akathisia can be attributed to low activity of dopaminergic projections from the midbrain to the ventral striatum. However, the exact pathophysiological mechanism of this extrapyramidal symptom remains unclear. This article describes a possible mechanism for drug-induced akathisia based on the differential functions of the core and shell portions of the nucleus accumbens. These ideas arise from contemporary concepts regarding the mechanisms of compulsion, impulsivity, and depression.