Cited research: Nature Neurosci. doi:10.1038/nn.2572 (2010)

Some antipsychotic drugs cause side effects that include slowed movements and shaking — apparently by temporarily shrinking a part of the brain responsible for motor control.

Heike Tost at the National Institute of Mental Health in Bethesda, Maryland, and her team injected seven healthy volunteers with haloperidol, a drug commonly prescribed for schizophrenia. Within two hours, volunteers showed signs of impaired motor ability that coincided with diminished grey-matter volume in their striatum — a brain region that modulates movement and other processes. Within a day, the brain returned to almost normal size.

Like most antipsychotics, haloperidol blocks a receptor for dopamine, a neurotransmitter that may regulate branching at the synapses through which neurons communicate. The team suggests that haloperidol reduces striatal size by decreasing synaptic growth. A.M.