Dissimilar patterns of degeneration in brain following four different addictive stimulants.

Different drugs of abuse that can produce psychosis in chronic users cause distinct patterns of brain damage. Continuous administration of D-amphetamine or cocaine over five days led to pronounced degeneration in the fasciculus retroflexus, a brain fiber bundle, while D-amphetamine also damaged the striatum. Phencyclidine (PCP) caused damage largely confined to the posterior entorhinal cortex, ventral dentate gyrus, and cingulate cortex. Methamphetamine, given in a high-dose but shorter regimen, caused widespread degeneration including in the striatum. These distinct patterns suggest two different anatomical locations may be involved in psychosis: the fasciculus retroflexus and the ventral parahippocampus and hippocampus.

Study at a glance

Abstract

Patterns of neural degeneration were compared following continuous administration of four drugs of addiction, each of which induces model psychoses in chronic addicts. D-amphetamine (D-Amph), cocaine (Coc), or phencyclidine (PCP) were administered continuously over a 5-day period. Both D-Amph and Coc induced pronounced degeneration in fasciculus retroflexus, but only D-Amph further induced substantial degeneration in striatum. Continuous PCP produced entirely different degeneration largely confined to the posterior entorhinal cortex, ventral dentate gyrus, and cingulate cortex. Methamphetamine (Meth) administered in the very high dose but less prolonged drug regimen often employed in studies of dopamine toxicity induced pronounced degeneration in striatum, but widespread degeneration in many other regions as well. These results indicate that drugs of abuse with psychotomimetic properties induce distinctively different patterns of neural degeneration, a finding with implications for theories of addiction and psychosis. They predict two different anatomical loci for alterations in psychosis: fasciculus retroflexus and ventral parahippocampus and hippocampus.