The DS was identified using the SDS. The MMP-9, BDNF, and COMT gene polymorphisms were genotyped. DNA methylation of the human endogeneous retrovirus type K (HERV-K) sequences was determined. Smell identification test was performed using the Sniffin’ Sticks test. For the assessment of executive function we used the Wisconsin Card Sorting Test, the Trail Making Test, Verbal Fluency Test Phonemic, Stroop Color Word Test and Go/No Go task.

There was no association between the examined functional gene polymorphisms, methylation levels and DS. Similarly, there was no relationship between overall odor identification abilities and the deficit/non-deficit dichotomy. The results tended to indicate specific problems in the identification of few odors in DS. DS, compared with the non-deficit group, obtained lower scores in the WCST and TMT and exhibited greater interference within concept formation and non-verbal cognitive flexibility. Furthermore, in patients with the first schizophrenia-like episode, the number of circulating Lin (-)/CD45 (-)/CD34 (+) very small embryionic like stem cells (VSELs) and the S1P plasma level were the best predictors of risk and are proposed as novel markers for the first “schizophrenic” episode of psychosis.

The authors declare that they have no competing interest.