Cytomegalovirus infection and IQ in patients with severe mental illness and healthy individuals

Dimitrios Andreou,Kjetil Nordbø Jørgensen,Laura A Wortinger,Kristine Engen,Anja Vaskinn,Torill Ueland,Robert H Yolken,Ole A Andreassen,Ingrid Agartz

doi:10.1016/j.psychres.2021.113929

Abstract

Cytomegalovirus (CMV) infection in immunocompetent adults is usually asymptomatic, but results in lifelong latency. Infection occurring congenitally or in immunodeficiency can lead to cognitive impairment. We aimed to investigate the associations between CMV exposure and intelligence quotient (IQ) in patients with schizophrenia spectrum disorders (SZS), bipolar spectrum disorders (BDS) and healthy controls (HC). CMV immunoglobulin G antibody concentrations were measured by immunoassay and expressed as dichotomous measures (seropositive/CMV+ vs. seronegative/CMV-). Based on a significant CMV-by-diagnosis-by-sex interaction on IQ, we investigated main and interaction effects of CMV and sex on IQ in each diagnostic category. Significant CMV-by-sex interactions were found in patient groups. In SZS, CMV+ female patients (n = 50) had significantly lower IQ than CMV- female patients (n = 33), whereas CMV+ (n = 48) and CMV- (n = 45) male patients did not differ in IQ. In BDS, CMV+ (n = 49) and CMV- (n = 37) female patients did not differ in IQ, whereas CMV+ male patients (n = 33) had significantly higher IQ than CMV- male patients (n = 32). Among HC, CMV+ (n = 138) and CMV- (n = 118) male participants as well as CMV+ (n = 125) and CMV- (n = 93) female participants did not differ in IQ. Our findings suggest that CMV exposure may affect IQ in patients with severe mental illness but not HC.

Highlights

The herpes virus cytomegalovirus (CMV) has a seroprevalence of 40100% in different populations, mainly depending on sex, age, ethnicity and socioeconomic status (Cannon et al, 2010; Dupont and Reeves, 2016)
We studied the role of CMV exposure on general intelligence in pa tients with schizophrenia spectrum disorders (SZS), bipolar spectrum disorders (BDS) and healthy controls (HC)
There were no significant differences between CMV- and CMV+ patients in the analyzed groups in terms of age, education years, duration of illness, Positive and Negative Syndrome Scale (PANSS), Young Mania Rating Scale (YMRS) and IDSC scores, tobacco use or handedness

Summary

Introduction

The herpes virus cytomegalovirus (CMV) has a seroprevalence of 40100% in different populations, mainly depending on sex, age, ethnicity and socioeconomic status (Cannon et al, 2010; Dupont and Reeves, 2016). Both conditions have been suggested to occur in severe mental illness (SMI) (Goldsmith et al, 2016; Hope et al, 2009; Najjar et al, 2017; Patel and Frey, 2015) In this context, interleukin 6 (Il-6), a pro-inflammatory cytokine which profoundly facilitates CMV reactivations (Reeves and Compton, 2011), is increased in patients with schizophrenia (Potvin et al, 2008) as well as in children with an increased future risk for psychosis (Khandaker et al, 2014). These findings might suggest that patients with SMI may be sus ceptible to CMV infection

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