The Effects of Environmental Enrichment on the Behavioral Profile of an Attention-Deficit/Hyperactivity Disorder Animal Model: A Systematic Review and Meta-Analysis.

In preclinical research, animal models are a valid alternative for studying both the genetics and environmental factors related to human psychopathologies. Indeed, in the last few decades, a great emphasis has been placed on the spontaneously hypertensive rat (SHR) inbred strain as an attention-deficit/hyperactivity disorder (ADHD) animal model. Therefore, this systematic review and meta-analysis aim to evaluate the effects of environmental enrichment (EE) on the behavior profile of the SHRs. All methods used to conduct the review were registered a priori on the PROSPERO platform (CRD42023442128). Our searches found 142 articles indexed in the electronic databases EMBASE, MEDLINE via PubMed, Scopus, and Web of Science. According to the eligibility criteria, six articles were included in the review. The meta-analysis demonstrated that EE decreased locomotor activity (SMD = -1.85, 95% CI = -3.18 to -0.52, Z = 2.72, p = 0.007, τ2 = 2.07, I2 = 86%) and enhanced memory (SMD = 1.32, 95% CI = 0.83 to 1.80, Z = 5.32, p < 0.001, τ2 = 0, I2 = 0%) in SHRs. Therefore, EE appears to have a beneficial effect on the behaviors of the SHR strain and could be considered in the search for nonpharmacological approaches in ADHD research.