Prevalence and correlates of neurological soft signs in healthy controls without family history of any mental disorder: A neurodevelopmental variation rather than a specific risk factor?

OBJECTIVE: Neurological soft signs (NSS) are a group of minor non-localizable neurological abnormalities found more often in patients with schizophrenia and other mental disorders. The aim of the current study was to investigate their prevalence and correlates in healthy controls without family history of any mental disorder.

MATERIAL AND METHODS: The study sample included 122 normal subjects (66 males and 56 females; aged 32.89 ± 9.91 years old). The assessment included the Neurological Evaluation Scale (NES), and a number of scales assessing the subthreshold symptoms (MADRS, STAI) and functioning (GAF). Data on a number of socio-demographic variables were also gathered. The statistical analysis included the development of basic statistics tables and the calculation of Pearson correlation coefficients.

RESULTS: The results of the current study suggest that more than half of the study sample manifested at least one NSS and approximately 5% more than four. Still, the reported prevalence and NES scores are lower form those reported in the literature probably because of the carefully selected study sample. There were no significant correlations between NSS and any socio-demographic or clinical variable.

DISCUSSION: The current study is the first to study NSS in subjects without family history of any mental disorder and reports the presence of frequent silent neurodevelopmental events in the general population, probably in the form of a neurodevelopmental variation and possibly a weak generic rather than specific risk factor.