Neurological soft signs in patients with schizophrenia and their unaffected siblings: frequency and correlates in two ethnic and socioeconomic distinct populations

Abstract

Recent studies have suggested that ethnicity and socioeconomic status may have an impact on the frequency and significance of neurological soft signs (NSS). However, this impact has not been adequately assessed. The objectives were to determine the NSS scores in patients with schizophrenia and their unaffected siblings and to examine the clinical and therapeutic correlates of NSS in two ethnic and socioeconomic distinct populations. Two independent replicate studies were carried out: (1) a French Caucasian sample of 69 patients with schizophrenia, 43 of their unaffected siblings and 108 control subjects; (2) a Tunisian sample of 66 patients with schizophrenia, 31 of their unaffected siblings and 60 control subjects. NSS were assessed with a multidimensional scale, previously validated in drug-naïve and treated samples of patients with schizophrenia. Both patient groups were assessed with the positive and negative syndrome scale (PANSS), the clinical global impressions (CGI) and the global assessment of functioning. NSS total scores were significantly higher in patients with schizophrenia comparatively to siblings and to controls in both studies. The two sibling groups had also higher NSS scores than controls. In addition, NSS total scores were correlated to the PANSS negative and disorganization sub-scores, to the CGI-severity of illness and to a low educational level in both studies. These studies provide a confirmation in two distinct samples of the high prevalence of NSS in patients with schizophrenia, and in their biological relatives, independently of their respective ethnic and socioeconomic origins.

Cognitive control deficit in patients with first-episode schizophrenia is associated with complex deviations of early brain development

“…8 Furthermore, non-right-handedness, including mixed-and lefthandedness, which is considered to result from early neurodevelopmental "failure to establish cerebral asymmetry," 23 is more frequent in patients with schizophrenia than in healthy individuals 23 and is associated with executive impairments. 12 Finally, NSS, referred to as the minor, nonlocalizable defects in motor coordination, motor integration and sensory integration, 11 are a clinical marker of pre-and perinatal deviance; 22,35 are much more frequent in patients with schizophrenia and their siblings than in controls; 36 and are associated with cognitive deficits, including executive functions. 11,32 The intensity of NSS may vary in the course of illness with acuity of the disorder.…”

Neurological soft signs as an endophenotype in siblings of deficit versus nondeficit schizophrenic patients

“…Patients with the deficit syndrome/subtype have poorer quality of life and a more severe form of the illness [24], more cognitive impairment, and more frequent side effects, especially tardive dyskinesia [25,26]. Early intervention, as suggested by some, in individuals who appear to have very early symptoms of schizophrenia but who have not yet met DSM-IV criteria for the disorder is recommended [27], with recent advances in neurosciences prompting considerations of schizophrenia from a preventive perspective through either elucidation of potential causal risk factors and/or research on risk markers [13].…”

“…In the sensory subtests, a larger number of HCs (34) obtained low scores (0-3) compared with S-NDSZ (2), and the number of S-DSZ to obtain low scores was the smallest. However, a larger number of S-DSZ (9) obtained high scores (12)(13)(14) compared with S-NDSZ (0) and HCs (0). The results of the sensory subtests were insignificant (P = 0.34).…”

“…Hypothesis and objective of the study NSS, as a candidate endophenotype of schizophrenia, are more prevalent in patients than in their unaffected relatives or when compared with the general population [8,13,18]. However, to our knowledge, none of the studies have compared the prevalence of such an endophenotype in the siblings of different subtypes of schizophrenic patients (DSZ and NDSZ) and in controls.…”

“…One of the important endophenotypes of schizophrenia is neurological soft signs (NSS) [12,13], which are nonlocalizing neurological abnormalities that are observed when an individual performs certain simple tasks and are established to be an area of abnormality in schizophrenia and related disorders, suggesting evidence of brain dysfunction [14,15]. They are presumed to have genetic origins because they are more frequently present in schizophrenic patients than in other psychiatric patients and nonpsychiatric comparison individuals and, interestingly enough, in relatives of schizophrenic patients who are intermediate between patients and normal comparison individuals [16,17].…”