Contrasting effects of haloperidol and lithium on rodent brain structure: A magnetic resonance imaging study with postmortem confirmation

Background: Magnetic resonance imaging (MRI) studies suggest that antipsychotic -treated patients with schizophrenia show a decrease in gray-matter volumes, whereas lithium-treated patients with bipolar disorder show marginal increases in gray-matter volumes. Although these clinical data are confounded by illness, chronicity, and other medications, they do suggest that typical antipsychotic drugs and lithium have contrasting effects on brain volume. Methods: Rodent models offer a tractable system to test this hypothesis, and we therefore examined the effect of chronic treatment (8 weeks) and subsequent withdrawal (8 weeks) with clinically relevant dosing of an antipsychotic (haloperidol, HAL) or lithium (Li) on brain volume using longitudinal in vivo structural MRI and confirmed the findings postmortem using unbiased stereology. Results: Chronic HAL treatment induced decreases in whole brain volume (-4%) and cortical gray matter (-6%), accompanied by hypertrophy of the corpus striatum (+14%). In contrast, chronic Li treatment induced increases in whole-brain volume (+5%) and cortical gray matter (+3%) without a significant effect on striatal volume. Following 8 weeks of drug withdrawal, HAL-induced changes in brain volumes normalized, whereas Li-treated animals retained significantly greater total brain volumes, as confirmed postmortem. However, the distribution of these contrasting changes was topographically distinct: with the haloperidol decreases more prominent rostral, the lithium increases were more prominent caudal. Conclusions: The implications of these findings for the clinic, potential mitigation strategies, and further drug development are discussed.