Neurological soft signs in schizophrenia: a meta-analysis.
BACKGROUND
Neurological soft signs (NSS) are hypothesized as candidate endophenotypes for schizophrenia, but their prevalence and relations with clinical and demographic data are unknown. The authors undertook a quantification (meta-analysis) of the published literature on NSS in patients with schizophrenia and healthy controls. A systematic search was conducted for published articles reporting NSS and related data using standard measures in schizophrenia and healthy comparison groups.


METHODS
A systematic search was conducted for published articles reporting data on the prevalence of NSS in schizophrenia using standard clinical rating scales and healthy comparison groups. Meta-analyses were performed using the Comprehensive Meta-analysis software package. Effect sizes (Cohen d) indexing the difference between schizophrenic patients and the healthy controls were calculated on the basis of reported statistics. Potential moderator variables evaluated included age of patient samples, level of education, sample sex proportions, medication doses, and negative and positive symptoms.


RESULTS
A total of 33 articles met inclusion criteria for the meta-analysis. A large and reliable group difference (Cohen d) indicated that, on average, a majority of patients (73%) perform outside the range of healthy subjects on aggregate NSS measures. Cognitive performance and positive and negative symptoms share 2%-10% of their variance with NSS.


CONCLUSIONS
NSS occur in a majority of the schizophrenia patient population and are largely distinct from symptomatic and cognitive features of the illness.
Chan
Raymond C K
RC
Key Laboratory of Mental Health, Institute of Psychology, Chinese Academy of Sciences, 4A Datun Road, Beijing 100101, China. rckchan@psych.ac.cn
Xu
Ting
T
Heinrichs
R Walter
RW
Yu
Yue
Y
Wang
Ya
Y
D016022:Case-Control Studies; D003071:Cognition; D058068:Endophenotypes; D005190:Family / Q000523:psychology*; D006801:Humans; D009460:Neurologic Examination; D015995:Prevalence; D011597:Psychomotor Performance; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics*; D012565:Schizophrenic Psychology; D012680:Sensitivity and Specificity