Abstract
BACKGROUND AND HYPOTHESIS: psychotic disorders induced by substances like marijuana, amphetamines and methamphetamines (SIPDs) are a growing mental health problem, yet the question do they represent a separate psychotic class independent from schizophrenia (SZ) still stands. Studies comparing clinical and cognitive performance of SIPD and SZ patients have produced inconsistent results. STUDY DESIGN: we performed a cross-sectional analysis of 62 subjects divided into two statistically matched groups (n = 31 each) with SZ and SIPD respectively. We compared the clinical severity of their symptoms as measured by the positive and negative PANSS scores. We then applied the following neurocognitive battery - 10 Words Memory Test of Luria for verbal learning and verbal memory; Digit Symbol Substitution Test (DSST) and Benton Visual Retention Test for processing speed and visual memory; Trail Making Test Part A & B for attention and cognitive flexibility (along with DSST); Logical Memory Test (LMT) for episodic memory and thinking disorders; Verbal Fluency Test (VFT) for semantic memory and language. We referenced the performance results of the two groups to the normative values of each of the tests. STUDY RESULTS: SZ subjects had significantly higher positive and negative PANSS scores and greater impairment in all cognitive domains except semantic memory and language (VFT). Compared to the normative values of all tests both SZ and SIPD patients performed poorer. CONCLUSIONS: Our data support the assumption that the two conditions share a common underlying neurobiological vulnerability that is more pronounced quantitatively in schizophrenia.