Aerobic Exercise and Cognition in People With Schizophrenia

RESEARCH UPDATE

Schizophrenia is associated with impaired cognition, which persists despite current treatments, and is an important determinant of quality of life and overall function. There is limited evidence for the efficacy of pharmacological treatments for this indication. Cognitive remediation therapy is a non-pharmacological intervention associated with improved cognitive functioning in patients who have schizophrenia, with a moderate effect size.¹

Physical activity can improve symptoms and social functioning in patients with schizophrenia.² In the general population, exercise has been associated with modest improvements in cognition, but this has not been adequately explored in patients with schizophrenia. Firth and colleagues³ conducted a meta-analysis of the effects of exercise on global cognition in schizophrenia.

Two study authors performed independent searches of multiple electronic databases, including MEDLINE, PsycINFO, Embase, Google Scholar, and the Cochrane Central Register of Controlled Trials. They looked for all published studies of neurocognitive outcomes of exercise interventions in patients with schizophrenia compared with controls.

They included studies in which at least 80% of the sample had a diagnosis of nonaffective psychotic disorder, or outcome data were reported for patients with nonaffective psychotic disorders separate from subjects with other diagnoses.

Exercise was defined as structured and repetitive physical activity with the objective of improving or maintaining physical fitness. Studies of yoga or tai chi alone were excluded, as were studies in which exercise was an active control for a different cognitive intervention. If exercise was used in combination with other treatments, then the study was included only if the non-exercise interventions were controlled for in the comparison.

The initial database search yielded 2115 results. Based on titles and abstracts, full-text versions were retrieved for 43 articles. Ten studies, which comprised 221 patients assigned to exercise and 234 to control conditions, were eligible for inclusion; 92.1% of patients had a diagnosis of schizophrenia or schizoaffective disorder.

The study sample had a mean age of 37 and an illness duration of 13 years, and was 56% male. Exercise programs were a mean of 12 weeks with about 3 sessions per week of 20 to 60 minutes’ duration each. Interventions included cycle ergometers/treadmills, bodyweight exercises, interactive video games, and free weights.

The authors found that exercise interventions significantly improved global cognition (Hedges g = 0.33), working memory (g = 0.39), attention/vigilance (g = 0.20), and social cognition (g = 0.27), with a small to moderate effect size and no evidence of statistical heterogeneity or publication bias.

Exercise interventions supervised by physical activity professionals (eg, physical trainers), but not by other professionals (eg, research staff), were associated with significantly improved cognition.

Exercise as a stand-alone intervention was associated with improved cognition, whereas exercise as an add-on to cognitive remediation therapy was not. No other demographic characteristics or intervention factors moderated associations with cognitive performance.

The bottom line
The authors found modest, but robust evidence that (aerobic) exercise improves global cognition in patients with schizophrenia with a similar magnitude as cognitive remediation therapy.

Disclosures:

Dr. Miller  is Associate Professor in the Department of Psychiatry and Health Behavior at  Augusta University in Augusta, GA, and Schizophrenia Section Editor for Psychiatric Times. He reports no conflicts of interest concerning the subject matter of  this article.

References:

1. Wykes T, Huddy V, Cellard C, et al. A meta-analysis of cognitive remediation for schizophrenia: methodology and effect sizes. Am J Psychiatry. 2011;168:472-485.

2. Firth J, Cotter J, Elliott R, et al. A systematic review and meta-analysis of exercise interventions in schizophrenia patients. Psychol Med. 2015;45:1343-1361.

3. Firth J, Stubbs B, Rosenbaum S, et al. Aerobic exercise improves cognitive functioning in people with schizophrenia: a systematic review and meta-analysis. Schizophr Bull. 2016; doi:10.1093/schbul/sbw115.