Neurocognition in first-episode schizophrenia: A meta-analytic review.

Abstract

Compromised neurocognition is a core feature of schizophrenia. Following Heinrichs and Zakzanis's (1998) seminal meta-analysis of middle-aged and predominantly chronic schizophrenia samples, the aim of this study is to provide a meta-analysis of neurocognitive findings from 47 studies of first-episode (FE) schizophrenia published through October 2007. The meta-analysis uses 43 separate samples of 2,204 FE patients with a mean age of 25.5 and 2,775 largely age- and gender-matched control participants. FE samples demonstrated medium-to-large impairments across 10 neurocognitive domains (mean effect sizes from -0.64 to -1.20). Findings indicate that impairments are reliably and broadly present by the FE, approach or match the degree of deficit shown in well-established illness, and are maximal in immediate verbal memory and processing speed. Larger IQ impairments in the FE compared to the premorbid period, but comparable to later phases of illness suggests deterioration between premorbid and FE phases followed by deficit stability at the group level. Considerable heterogeneity of effect sizes across studies, however, underscores variability in manifestations of the illness and a need for improved reporting of sample characteristics to support moderator variable analyses.

Preserved, deteriorated, and premorbidly impaired patterns of intellectual ability in schizophrenia.

“…There is substantial consensus in the literature that impairments in various cognitive domains are not reducible to secondary influences that reflect treatment with antipsychotic medications, recurrent hospitalization, social disadvantage, or years of chronic stress associated with receiving the diagnosis (Torrey, 2002;Ma et al, 2007). They also persist following the amelioration of clinical symptoms and over the course of the illness (Elvevag & Goldberg, 2000;Heinrichs & Zakzanis, 1998;Hoff et al, 1999;Hughes et al, 2003;Martinez-Aran et al, 2002;Rund et al, 2004); exist in the pre-psychotic period and at the onset of illness (Brewer et al, 2005;Johnstone, Ebmeier, Miller, Owens, & Lawrie, 2005;Lencz et al, 2006;Lewandowski, Cohen, & Ongur, 2011;Mesholam-Gately, Giuliano, Goff, Faraone, & Seidman, 2009); occur in unaffected people with elevated risk Fusar-Poli et al, 2007;Sitskoorn, Aleman, Ebisch, Appels, & Kahn, 2004;Whalley, Harris, & Lawrie, 2007); are unrelated to the chronicity of the illness or its duration (Heaton et al, 2001;Hoff et al, 1999;Kurtz, Seltzer, Ferrand, & Wexler, 2005), and are more severe in schizophrenia, as compared with other psychotic illnesses (Altshuler et al, 2004).…”

MK-801-induced impairments on the trial-unique, delayed nonmatching-to-location task in rats: effects of acute sodium nitroprusside

“…Due to their high prevalence, robustness, and severity, working memory deficits have been proposed as a core component to the diagnosis (Mesholam-Gately et al 2009). Further, these impairments critically contribute to other symptoms and neuropsychological deficits in schizophrenia (Silver et al 2003; Lewis and Moghaddam 2006).…”

“…Working memory impairments are robust and highly prevalent among patients (Mesholam-Gately et al 2009). The severity of impairment is highlighted by the collection of working memory vulnerabilities, including the inability to maintain information across a delay or protect it from interference (Fleming et al 1995;Kim et al 2004;Fatouros-Bergman et al 2014).…”

Negative Symptoms and Executive Function in Schizophrenia: Does Their Relationship Change with Illness Duration?

“…Nowadays, the existence of a cognitive deficit in this disorder has been well documented [15]. Cognitive dysfunction is present from the first psychotic episode, or even earlier [16,17,18,19,20,21,22], and is thought to be a primary or core component of the illness [23,24]. Interest in cognition is growing in recent years since cognitive impairment is currently considered to be one of the main factors influencing global functioning and prognosis in schizophrenia [25,26,27,28,29].…”