The cohort with childhood-onset schizophrenia was made up of eight girls and 13 boys with a mean age of 14 years (SD=1). The healthy comparison group was composed of 12 girls and 15 boys with a mean age of 13 years (SD=2). Neither age (t=1.56, N=21, 27, p<0.13) nor sex distribution (χ2=1.96, df=1, p<0.67) differed between the two groups. After onset of symptoms, the subjects with childhood-onset schizophrenia had an estimated mean full-scale IQ of 77 (SD=22, range=48–120), which differed significantly from that of the healthy comparison subjects (estimated mean full-scale IQ=121, SD=12, range=97–141) (Wilcoxon z=4.21, N=48, p<0.0001). Interrater reliability was good; kappa was >0.40, and percent agreement was >75% on all items, except four frontal release signs (snout, palmomental, glabellar tap, and jaw jerk), in which percent agreement ranged from 43% to 57%. Isolated abnormalities of cranial nerves, primary sensation, and strength occurred equally in both groups. Gaze impersistence was more common in the subjects with childhood-onset schizophrenia (χ2=14.15, df=1, p<0.001). Similarly, sensory integration face-hand test results were more frequently abnormal in the patients with childhood-onset schizophrenia (χ2=8.44, df=1, p<0.004). A higher incidence of increased passive tone while reinforcing movements were made with the opposite arm was especially common in healthy comparison adolescents younger than age 15, whereas the adolescents with childhood-onset schizophrenia were significantly more likely to exhibit increased passive tone in the absence of reinforcement, independent of age (χ2=7.31, df=1, p<0.03). Corticospinal tract signs were also significantly more common in the cohort with childhood-onset schizophrenia (χ2=7.31, df=1, p<0.03). Coordination was often abnormal in both groups; however, all of the healthy comparison adolescents with poor coordination were younger than age 15 (p<0.04, Fisher’s exact test), whereas no grouping by age was present in the cohort with childhood-onset schizophrenia (p>0.99, Fisher’s exact test). Choreiform movements were similarly significantly clustered in the younger healthy comparison adolescents (p<0.02, Fisher’s exact test) but were equally present in both younger and older adolescents with childhood-onset schizophrenia (p>0.99, Fisher’s exact test).
Twelve healthy comparison adolescents but only three adolescents with childhood-onset schizophrenia exhibited no primitive reflexes (χ2=0.03, df=1, p<0.056). The number of primitive reflexes was significantly inversely correlated with age in the healthy comparison cohort (rs=–0.57, N=27, p<0.002) but not in the cohort with childhood-onset schizophrenia (rs=0.05, N=21, p<0.84).
At least one sign was present at neurologic examination in all (100%) of the adolescents with childhood-onset schizophrenia and in 26 (96%) of the 27 healthy comparison subjects. The group with schizophrenia had a mean of 6 (SD=2, range=2–10) signs per subject. The healthy comparison group had a mean of 4 (SD=2, range=0–8) signs per subject (Wilcoxon z=–3.30, N=18, 27, p<0.001). Because examination of primitive reflexes can have low interrater reliability (38), analyses were repeated with those signs excluded. Significant differences persisted.
No significant correlations were found between either the total number or type of abnormalities by specific neurologic subcategory and either ventricular size or total brain volume. Full-scale IQ correlated only inversely with the number of primitive reflexes in the healthy comparison cohort (rs=–0.64, N=27, p<0.02) but not in the patients.
The total number of neurologic signs decreased with age in the healthy comparison group (rs=–0.73, N=27, p<0.0001) but not in the group with childhood-onset schizophrenia (rs=–0.07, N=18, p<0.78). These correlations differed significantly (Wilcoxon z=–2.56, p=0.005, Fisher’s r-to-z transformation) (F1).