Reading skills deficits in people with mental illness: A systematic review and meta-analysis

Abstract

Background: Good reading skills are important for appropriate functioning in everyday life, scholastic performance, and the chances of acquiring a higher socioeconomic status. We conducted the first systematic review and meta-analysis to quantify possible deficits in specific reading skills in people with a variety of mental illnesses, including personality disorders. Methods: We performed a systematic search of databases (Academic Search Complete, CINAHL Plus, PsycInfo, PsycARTICLES, SocINDEX, MEDLINE, and PubMed) from inception until February 2020 and conducted random-effects meta-analyses. Results: The search yielded 34 studies with standardised assessments of reading skills in people with one or more mental illnesses. Of these, 19 studies provided data for the meta-analysis. Most studies (n=27; meta-analysis, n=17) were in people with schizophrenia and revealed large deficits in phonological processing (Hedge's g=-0.88, p<0.00001), comprehension (Hedge's g=-0.96, p<0.00001) and reading rate (Hedge's g=-1.22, p=0.002), relative to healthy controls; the single-word reading was less affected (Hedge's g=-0.70, p<0.00001). A few studies in affective disorders and non-forensic personality disorders suggested weaker deficits (for all, Hedge's g<-0.60). In forensic populations with personality disorders, there was evidence of marked phonological processing (Hedge's g=-0.85, p<0.0001) and comprehension deficits (Hedge's g=-0.95, p=0.0003). Conclusions: People with schizophrenia, and possibly forensic populations with personality disorders, demonstrate a range of reading skills deficits. Future studies are needed to establish how these deficits directly compare to those seen in developmental or acquired dyslexia and to explore the potential of dyslexia interventions to improve reading skills in these populations.

Clarifying the roles of schizotypy and psychopathic traits in lexical decision performance

“…Our present findings show that elevated psychopathic traits and higher motor impulsivity in combination with non-native language proficiency are associated with poor lexical recognition. Considering previous findings of impaired reading skills in patients with psychopathy and/or a history of violence ( Vanova et al, 2021 ), our results suggest the existence of a continuum of reading skill deficits related to elevated psychopathic traits and have implications for future research adopting a dimensional approach to psychopathology. Future research could establish whether the mechanisms underlying psychopathy/schizotypy-lexical recognition association in the normative population are shared with those underlying poor reading skills in clinical populations, what it means in terms of vulnerability to dyslexia, and clarify the roles of specific symptoms and illness-related factors (e.g., medication) ( de Boer et al, 2020 ).…”

“…One study ( Harmon-Jones et al, 1997 ) observed higher attentional and non-planning, but not motor, impulsivity to be related to poor reading comprehension and accuracy, while another study ( De Pascalis et al, 2009 ) reported a negative influence of higher overall impulsivity on the RTs and accuracy when processing words incongruent with presented sentences. Previous research suggests intact reading skills in people with affective disorders ( Vanova et al, 2021 ), and no effect of subclinical depression and anxiety in word-nonword recognition ( Li et al, 2014 ; Notebaert et al, 2019 ; Stevens et al, 2015 ; White et al, 2010 ). However, much of the evidence for reading skills deficits in clinical populations comes from small sample studies with high heterogeneity, and rarely accounts for confounders such as medication ( Wright and Woods, 2020 ).…”

“…The present study, therefore, examined the relationship between schizotypy, psychopathy, impulsivity, affective traits, and LDT performance, in a general population sample. Based on previous findings ( Vanova et al, 2021 ), we hypothesised that higher schizotypy, psychopathy, and impulsivity will be associated with lower LDT performance. Furthermore, we examined the common and unique contribution of schizotypy, psychopathy and/or impulsivity to LDT performance and explored the role of language familiarity (native versus non-native speakers) in these associations.…”

“…A recent meta-analysis ( Vanova et al, 2021 ) revealed significant deficits in reading skills in schizophrenia, personality disorders and/or psychopathy, but not in affective disorders. In the context of LDT, individuals with schizophrenia showed poorer word-nonword recognition and longer reaction times (RTs) than controls in some ( Hokama et al, 2003 ), but not all studies ( Natsubori et al, 2014 ; Tan et al, 2016b ).…”

“…Psychopathy has been associated with poorer reading skills in forensic and community samples ( Vanova et al, 2021 ). Higher impulsive-antisocial psychopathy scores correlate with poorer overall word-nonword recognition ( Heritage and Benning, 2013 ; Lorenz and Newman, 2002 ), and slower RTs, especially in forensic samples ( Kiehl et al, 2004 ; Reidy et al, 2008 ).…”