Growing evidence has shown that psychometrically identified schizotypes among student populations have subtle cognitive impairments in several domains such as attention, working memory and executive function, but the possible association between psychometric schizotypy in adult populations and cognitive function has not been well documented. Here we examined the association between schizotypal traits as assessed by the Schizotypal Personality Questionnaire (SPQ) and cognitive function including memory, attention, executive function, and general intelligence in 124 healthy adults. Cognitive functioning was assessed with the Wechsler Memory Scale-Revised (WMS-R), the Wechsler Adult Intelligence Scale-Revised (WAIS-R), and the Wisconsin Card Sorting Test (WCST). SPQ scores showed a significant inverse correlation with verbal IQ and the information, comprehension and similarities subtests. No correlation was found between SPQ scores and memory, attention, performance IQ, or executive functioning. These results indicate that schizotypal traits in healthy adults are associated with verbal IQ decrements, suggesting that schizotypal traits themselves, even at a non-clinical level, may play unfavorable roles in cognitive functioning, which is in line with the viewpoint that schizotypy is on a continuum with normality, with its extreme form being clinically expressed as schizophrenia.
"(2015), http://dx.doi.org/10.1016/j.schres.2015.05.026 end of the schizophrenia spectrum, i.e., sub-threshold psychotic states in non-clinical community samples. Measures that encompass this extended psychosis phenotype – schizotypal personality and subclinical psychosis – have been shown to be negatively related to executive functions (Gooding et al., 1999; Lenzenweger and Korfine, 1994), sustained attention (Chen et al., 1998; Gooding et al., 2006), verbal intelligence (Noguchi et al., 2008), working memory (Gooding and Tallent, 2003; Kelleher et al., 2012), or processing speed (Hengartner et al., 2014; Kelleher et al., 2012). "
"However, it is important to note that although our 'high schizotypal' group displays some schizotypal personality traits, these schizotypal traits are on a continuum; thus, our 'high schizotypal' group would not meet criteria for diagnosis of schizotypal personality disorder but may still be useful to examine the effects of schizotypal personality traits. Noguchi et al.  examined the association between schizotypal traits in healthy adults and cognitive function and found that SPQ scores showed a significant inverse correlation with verbal IQ and the information, comprehension and similarities subtests from the Wechsler Adult Intelligence Scale-Revised. McClure et al.  showed that a cognitive composite score was significantly impaired in schizotypal personality disorder relative to healthy controls and avoidant personality disorder. "
[Show abstract][Hide abstract] ABSTRACT: The brain derived neurotrophic factor (BDNF) val66met polymorphism rs6265 influences learning and may represent a risk factor for schizophrenia. Healthy people with high schizotypal personality traits display cognitive deficits that are similar to but not as severe as those observed in schizophrenia and they can be studied without confounds of antipsychotics or chronic illness. How genetic variation in BDNF may impact learning in individuals falling along the schizophrenia spectrum is unknown. We predicted that schizotypal personality traits would influence learning and that schizotypal personality-based differences in learning would vary depending on the BDNF val66met genotype. Eighty-nine healthy adults completed the Schizotypal Personality Questionnaire (SPQ) and a probabilistic association learning test. Blood samples were genotyped for the BDNF val66met polymorphism. An ANOVA was performed with BDNF genotype (val homozygotes and met-carriers) and SPQ score (high/low) as grouping variables and probabilistic association learning as the dependent variable. Participants with low SPQ scores (fewer schizotypal personality traits) showed significantly better learning than those with high SPQ scores. BDNF met-carriers displaying few schizotypal personality traits performed best, whereas BDNF met-carriers displaying high schizotypal personality traits performed worst. Thus, the BDNF val66met polymorphism appears to influence probabilistic association learning differently depending on the extent of schizotypal personality traits displayed.
Behavioural Brain Research 08/2014; 174:137-142. DOI:10.1016/j.bbr.2014.07.041 · 3.03 Impact Factor
"Schizotypy has been correlated with neurocognitive, behavioral , and social deficits, which are qualitatively similar to those found in patients with schizophrenia but quantitatively less severe (Croft et al., 2001; Noguchi et al., 2008; Wilson et al., 2008; "
[Show abstract][Hide abstract] ABSTRACT: "Schizotypy" is a latent organization of personality related to the genetic risk for schizophrenia. Some evidence suggests that schizophrenia and schizotypy share some biological features, including a link to dopaminergic D2 receptor signaling. A polymorphism in the D2 gene (DRD2 rs1076560, guanine > thymine (G > T)) has been associated with the D2 short/long isoform expression ratio, as well as striatal dopamine signaling and prefrontal cortical activity during different cognitive operations, which are measures that are altered in patients with schizophrenia. Our aim is to determine the association of schizotypy scores with the DRD2 rs1076560 genotype in healthy individuals and their interaction with prefrontal activity during attention and D2 striatal signaling. A total of 83 healthy subjects were genotyped for DRD2 rs1076560 and completed the Schizotypal Personality Questionnaire (SPQ). Twenty-six participants underwent SPECT with [(123)I]IBZM D2 receptor radiotracer, while 68 performed an attentional control task during fMRI. We found that rs1076560 GT subjects had greater SPQ scores than GG individuals. Moreover, the interaction between schizotypy and the GT genotype predicted prefrontal activity and related attentional behavior, as well as striatal binding of IBZM. No interaction was found in GG individuals. These results suggest that rs1076560 GT healthy individuals are prone to higher levels of schizotypy, and that the interaction between rs1076560 and schizotypy scores modulates phenotypes related to the pathophysiology of schizophrenia, such as prefrontal activity and striatal dopamine signaling. These results provide systems-level qualitative evidence for mapping the construct of schizotypy in healthy individuals onto the schizophrenia continuum.
Ahmed El-Missiry, Amira Elbatrawy, Marwa El Missiry, Dalia Abdel Moneim, Ramy Ali, Heba Essawy
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