Cognitive Functioning in Children and Adolescents in Their First Episode of Psychosis

Abstract

To investigate the relationship between cognition and prior cannabis use in children and adolescents presenting a first episode of psychosis. A total of 107 patients with first episode of psychosis and 96 healthy controls, aged 9 to 17 years, were interviewed about their previous substance use and to assess their cognitive functions. Patients were assessed while not using cannabis by means of a comprehensive neuropsychological battery. They were divided into 2 groups depending on the history of prior cannabis use: cannabis users (CU) and cannabis nonusers (CNU). Significant differences were found in all areas evaluated between the 3 groups. Both CU and CNU patients obtained lower scores than controls on verbal learning and memory and working memory. Patients with prior cannabis use performed better on some tests of attention (Continuous performance test (CPT) number of correct responses, p = 0.002; CPT average reaction time, p < 0.001) and executive functions (Trail Making Test, part B (TMT-B) number of mistakes, p < 0.001; Wisconsin Card Sorting Test (WCST) number of categories completed, p < 0.001) than CNU patients. CU patients performed better than CNU subjects on some cognitive measures. This may indicate lower individual vulnerability for psychosis in CU patients in whom cannabis use can be a precipitating factor of psychotic episodes.

The Impact of Cannabis Use on Cognitive Functioning in Patients With Schizophrenia: A Meta-analysis of Existing Findings and New Data in a First-Episode Sample

“…Five studies have examined cognitive functioning in a sample who used cannabis before the onset of psychosis. 25,26,33 However, the studies of Stirling et al, 33 Jockers-Scherubl et al, 19 and Schnell et al 20 included a chronic sample, and it was not possible to exclude the effects of cannabis use after the onset of psychosis or illness-related factors. While the studies of de la Serna et al 25 and Mata et al 26 were also FEP samples, they only assessed cannabis use in the previous one month or in the previous 12 months, meaning that their cannabis nonuser samples were likely to have also included patients who had a past history of cannabis use.…”

“…Five of these studies were excluded because: (1) they lacked data for calculating effect size, 22,23 , (2) the study sample included a mixture of patients with schizophrenia and affective disorders, 24 and (3) they were primarily FEP studies (too few studies in this group to conduct appropriate meta-analyses). 25,26 In 6 of the 10 studies included in the meta-analysis, cannabis use was defined as lifetime use and in the other 4 studies it was defined as recent use (current use or use in last 6 months). In 2 of the included studies, 27,28 not all patients in the substance-using groups were abusing cannabis, but they were still included in the meta-analysis since cannabis was the most commonly used substance within the samples.…”

Cannabis users have higher premorbid IQ than other patients with first onset psychosis

“…The first suggests that those psychotic subjects who use cannabis have less premorbid cognitive impairment than those who do not. This could be because good premorbid functioning is necessary to acquire and sustain an illegal drug habit (Joyal et al, 2003;Stirling et al, 2005;RodriguezSanchez et al, 2010) or because cannabis use increases the risk of psychosis in a subgroup of patients with less neurodevelopmental vulnerability (Løberg and Hugdahl, 2009;Schnell et al, 2009;de la Serna et al, 2010;Yücel et al, 2010;Leeson et al, 2012;Schnell et al, 2012).…”

Sex-specific cognitive abnormalities in early-onset psychosis

“…20 Verbal memory was measured with the Wechsler Memory Scale -Third Edition (WMS-III), covering logical memory (immediate), logical memory (delayed), and logical memory (recognition) 21 ; for verbal working memory, the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) backward digit span test was used. 18 Auditory attention was measured with the WISC-IV digit span test 20 ; processing speed, by digit symbol coding (WISC-IV). 20 Premorbid IQ was measured with the vocabulary subtest of the WISC-IV.…”

“…18,19 The neuropsychological battery employed in this study was designed to address the following domains: IQ, verbal memory, verbal working memory, auditory attention, processing speed, premorbid IQ, executive function, and visual memory.…”