Background
The extent to which socio-demographic, clinical, and premorbid adjustment variables contribute to cognitive deficits in first-episode schizophrenia spectrum disorders remains to be ascertained.
Aims
To examine the pattern and magnitude of cognitive impairment in first-episode psychosis patients, the profile of impairment across psychosis subtypes and the associations with premorbid adjustment.
Methods
226 first-episode psychosis patients and 225 healthy controls were assessed in the PEPsCog study, as part of the PEPs study.
Results
Patients showed slight to moderate cognitive impairment, verbal memory being the domain most impaired compared to controls. Broad affective spectrum patients had better premorbid IQ and outperformed the schizophrenia and other psychosis groups in executive function, and had better global cognitive function than the schizophrenia group. Adolescent premorbid adjustment together with age, gender, parental socio-economic status, and mean daily antipsychotic doses were the factors that best explained patients' cognitive performance. General and adolescent premorbid adjustment, age and parental socio-economic status were the best predictors of cognitive performance in controls.
Conclusions
Poorer premorbid adjustment together with socio-demographic factors and higher daily antipsychotic doses were related to a generalized cognitive impairment and to a lower premorbid intellectual reserve, suggesting that neurodevelopmental impairment was present before illness onset.
Cognitive deficits are considered core features of schizophrenia spectrum disorders and, among other reasons, they are considered important for their impact on functional outcome (Green et al., 2004). FEP represents an excellent opportunity for research, because confounding factors such as hospitalization, long-term treatments and chronicity are minimized (Goldberg et al., 2010).
The cognitive profile of schizophrenia patients has been widely detailed in research, presenting a generalized cognitive impairment and specific deficits in attention, memory and learning, executive functions, working memory and processing speed (Heinrichs and Zakzanis, 1998, Flashman and Green, 2004 and Reichenberg and Harvey, 2007). Regarding other psychotic disorders, research has focused primarily on the comparison between schizophrenia and psychotic affective disorders, reporting milder deficits in bipolar patients although qualitatively similar to patients with schizophrenia (Schretlen et al., 2007, Reichenberg et al., 2009 and Aas et al., 2014). Schizophrenic patients also show greater effect sizes in premorbid and current intelligence quotient (IQ) at illness onset when compared to other psychosis (Zanelli et al., 2010).
Several premorbid factors, such as a lower IQ and poorer adjustment, have been associated with cognitive impairment in the early phases of psychosis. However, there is no agreement on these findings. Otherwise, premorbid IQ (van Winkel et al., 2006) as well as IQ at psychosis onset (Leeson et al., 2009 and Leeson et al., 2010) have been shown to be predictors of functional outcome in the long term. These findings support the cognitive reserve theories (Barnett et al., 2006), which propose that patients with higher premorbid intellectual function have more resilience to cope with the neural damage associated with the illness, better brain structure or neural functionality compensating for the deficits.
Premorbid adjustment refers to a subject's social, interpersonal, academic and occupational functioning prior to the onset of psychotic symptoms (Addington and Addington, 2005). Poor premorbid adjustment has been related to higher rates of relapse and poorer clinical outcome (Addington and Addington, 2005 and Levy et al., 2012). Neurodevelopmental disturbances are assumed to underlie poor premorbid adjustment, which represents one of the key prognostic indicators of schizophrenia (McGlashan, 2008). The relationship between premorbid adjustment and cognitive functioning has been examined in several studies. In a sample of FEP, Rund et al. (2007) found that a good premorbid level of academic functioning was associated with better verbal learning outcomes 1 year after the episode and better working memory outcomes 2 years later. A strong association has been found between poor childhood academic functioning and poor outcomes on working memory tests (Larsen et al., 2004).
The “Phenotype–genotype and environmental interaction. Application of a predictive model in first psychotic episodes” or PEPs study is a multicentre, longitudinal, naturalistic, follow-up study designed to evaluate clinical, neuropsychological, neuroimaging, biochemical and genetic variables in a sample of 335 first-episode psychosis (FEP) patients in Spain, matched with healthy controls by age, sex and socio-economic status. Patients were recruited from sixteen centers located across Spain from April 2009 to April 2011. The aim of this project was to assess clinical characteristics, functional prognostic factors, diagnostic specificity of findings, and pathophysiological changes in the brain during the first 2 years after a first psychotic episode ( Bernardo et al., 2013).
The aims of the present study were to examine: 1) the pattern and magnitude of cognitive impairment in FEP patients after clinical stabilization of the acute episode; 2) the differences between psychosis subtypes and healthy control groups; 3) the relationship between premorbid adjustment abnormalities with cognitive impairment; and 4) the relative contribution of premorbid adjustment abnormalities to cognitive impairment taking account of the main socio-demographic and clinical variables.
