Have we reproduced Rat Park? Conceptual but not direct replication of the protective effects of social and environmental enrichment in addiction

Abstract

The Rat Park studies are classic experiments in addiction neuroscience, yet they have not been successfully replicated directly and several serious methodological criticisms have been raised. However, the conceptual reproducibility of the Rat Park studies is supported by both contemporaneous and subsequent research. Contemporaneous research on social and environmental enrichment frequently found social isolation rendered rats less sensitive to the effects of drugs of abuse. The Rat Park studies therefore confirmed the importance of social and environmental enrichment and extended this literature to suggest that enrichment reduced opioid consumption. Subsequent studies have also demonstrated social and environmental enrichment reduces drug consumption. However, there are also several papers reporting no effects of enrichment (or ‘negative’ results) and caveats from studies that show genes, age, sex and drug of abuse are all important parameters. While the Rat Park studies did not use methods that are reliable by current standards, enrichment has been shown to reliably reduce opioid consumption and this effect can generalise to other drugs of abuse.