The effects of positive and negative schizotypy on prepulse inhibition and cognitive functions
Η σχιζοτυπία (θετικά και αρνητικά συμπτώματα) και η σχέση της με την προπαλμική αναστολή και τις γνωστικές λειτουργίες του ατόμου
High schizotypal traits in the general population are conceptualized as part of a continuum in the liability to schizophrenia, which ranges from mild schizotypal traits, and schizotypal personality disorder to deteriorating schizophrenia. Previous studies have found a correlation between schizotypal traits and deficient cognitive functions as well as Prepulse Inhibition of the acoustic startle reflex (PPI), as in schizophrenia. However, significantly fewer studied have focused on the different dimensions, which constitute the construct of schizotypy and their subsequent effects on cognition and PPI. This thesis presents the concept of Cognitive-Perceptual (Positive symptomatology) and Interpersonal (negative symptomatology) schizotypal dimensions, as measured with the psychometric “Schizotypal Personality Questionnaire” (SPQ) instrument, and examines their effect on schizophrenia-related endophenotypes (cognitive functions and PPI) in healthy individuals in the general population.
Cognitive functions were assessed using a broad range of neuropsychological tasks and the startle response was recorded using an electromyographic startle system. First, a principal component analysis (PCA) was conducted to group all the cognitive variables into related factors. Then, regression analyses were run, in order to identify possible associations. Finally, we grouped our subjects into “Non-Schizotypal Prone, “High Positive Schizotypal” and “High Negative Schizotypal” groups, based on their scores in the Cognitive-Perceptual and Interpersonal indices of the SPQ.
Significant correlations were found between the Cognitive-Perceptual index and the cognitive factors “Perseveration”, “Problem Solving”, “Declarative Memory”, and “Episodic Memory”. Moreover, significant correlations were found between the Interpersonal index and “Inattention” and “Declarative Memory”. No correlation was
found between the Cognitive-Perceptual or the Interpersonal dimension of schizotypy and PPI. These findings suggest that although healthy individuals with positive or negative schizotypal traits share some cognitive deficits, PPI deficits may be more specific to schizophrenia and schizotypal personality disorder. The limitations of the study are also discussed.