Neurological soft signs in patients with treatment-resistant schizophrenia and their relationship with symptoms, premorbid adjustment, and functioning: a comparative study

BACKGROUND AND OBJECTIVES: Motor alterations in schizophrenia are important because they provide measurable, objective parameters. Neurological soft signs (NSS) are minor motor and sensory deficits. The study aimed to compare NSS in treatment-resistant schizophrenia (TRS) and non-TRS patients, their siblings, and healthy controls (HC), and to examine the associations of NSS with sociodemographic and clinical variables, premorbid adjustment, functioning, and negative and cognitive symptoms. METHODS: The study included 30 TRS patients, 30 non-TRS patients, 37 healthy siblings of the patients, and 30 HC. Neurological Evaluation Scale (NES) was administered to all participants to assess NSS. Brief Psychiatric Rating Scale (BPRS), Brief Negative Symptom Scale, Global Assessment of Functioning (GAF), Clinical Global Impression-Severity Scale (CGI-S), Premorbid Adjustment Scale-Childhood (PAS), and a cognitive battery were administered to patients. RESULTS: NSS were higher in the combined TRS and non-TRS patient group than in the sibling group, and higher in the sibling group than in HC. TRS patients had higher NES-Total, NES-Sensory Integration, and NES-Other Signs scores than non-TRS. NES-Total score was negatively correlated with GAF score and positively correlated with BPRS, CGI-S, and PAS-childhood. Poorer performance on cognitive tests assessing processing speed, working memory, and set-shifting was associated with more NSS. CONCLUSIONS: NSS were associated with greater illness severity, lower functioning, poorer premorbid adjustment, and reduced performance in processing speed, working memory, and set-shifting. Our findings suggest that there may be an association between NSS and treatment resistance in schizophrenia.