Association between Cardiovascular Risk Factors and Cognitive Disorders in Patients with Schizophrenia

Introduction

Schizophrenia is a serious disease that reduces the quality and length of life of sufferers, which is largely attributed to the increased occurrence of cardiovascular diseases in this population group. An important risk factor for cardiovascular diseases is metabolic syndrome, which is also observed to an increased extent in individuals with schizophrenia. This may be due to genetic predisposition, an unhealthy lifestyle associated with schizophrenia, but also antipsychotic treatment.

The interconnected relationship between cardiovascular diseases and cognitive impairment is evidenced by available data, which suggest that metabolic syndrome is a risk factor for the development of cognitive disorders in the general population, but also in patients diagnosed with schizophrenia. The presence of cognitive disorders is a characteristic feature of schizophrenia that correlates with functional outcomes.

Analyzed Data and Research Objectives

For the purpose of the meta-analysis, a literature search was conducted in the databases Embase, Scopus, MEDLINE, PubMed, and Cochrane, scientific conference abstracts, and clinical trial registries as of February 25, 2020. Studies that evaluated cognitive functions in patients with schizophrenia and schizoaffective disorder, the association between cardiovascular risk factors (including metabolic syndrome, diabetes, obesity, overweight, and insulin resistance) and outcomes achieved by these patients, and compared cognitive functions in patients with and without cardiovascular risk factors were included in the analysis.

A total of 27 studies with 10,174 participants met the inclusion criteria. Most of the studies were conducted in China (9; n = 3489), the United States (7; n = 3923), and Europe (7; n = 802). One study was from Singapore (n = 1719), and one each from India and Egypt (121 and 120 participants, respectively). Data extraction from the individual studies was performed by 2–3 independent examiners. The average age of the patients was 42.1 ± 8.7 years, the majority were men (63.8%; n = 6488), and the average duration of schizophrenia was 14.4 ± 8.2 years.

The primary objective was to assess overall cognitive functions using a clinically validated tool score, and the secondary objectives included the assessment of individual cognitive domains.

Findings

Significantly greater deterioration of overall cognitive functions was found in patients with metabolic syndrome (13 studies; n = 2800; effect size [ES] assessed with Hedges' g 0.31; 95% confidence interval [CI] 0.13–0.50; p = 0.001), diabetes (8 studies; n = 2976; ES 0.32; 95% CI 0.23–0.42; p < 0.001), and hypertension (5 studies; n = 1899; ES 0.21; 95% CI 0.11–0.31; p < 0.001). In patients with obesity, overweight, and insulin resistance, the deterioration of overall cognitive functions was insignificant.

Impaired performance in specific cognitive domains was associated with cognitive dysfunction and cardiovascular risk factors, in 5 domains in diabetics (attention/vigilance, reasoning/problem solving, thinking speed, verbal and visual learning) and in 4 domains in patients with metabolic syndrome (attention/vigilance, reasoning/problem solving, thinking speed, verbal learning) and arterial hypertension (reasoning/problem solving, thinking speed, verbal learning, and working memory).

Conclusion

The results of a large meta-analysis showed that in individuals with schizophrenia/schizoaffective disorder, the presence of metabolic syndrome, diabetes, and arterial hypertension is associated with a deterioration of overall cognitive functions and individual cognitive domains.

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Source: Hagi K., Nosaka T., Dickinson D. et al. Association between cardiovascular risk factors and cognitive impairment in people with schizophrenia: a systematic review and meta-analysis. JAMA Psychiatry 2021; 78 (5): 510–518, doi: 10.1001/jamapsychiatry.2021.0015.