Correlation of severity of psychiatric patients' delusions with right hemispatial inattention (left-turning behavior).

Studies associate psychotic disorders with various forms of subtle inattention to the right hemispace (left-turning behavior). The authors examined the correlation between this dopamine-related sign and severity of delusions (presumably dopaminergic symptoms) in 20 psychotic patients. Delusions were significantly correlated with severity of left-turning bias, and this neurological sign accounted for 33% of the variance in severity of delusions.

Subtle signs of prenatal maldevelopment of the hand ectoderm in schizophrenia: a preliminary monozygotic twin study.

Genes that predispose to psychosis may act by making individuals more vulnerable to the disruptive effects of various prenatal insults. Fetal organogenesis is mostly completed in the first prenatal trimester. The second trimester is a critical period of massive neuronal migration from the periventricular germinal matrix to the cortex. A peripheral appendage developing simultaneously with this neural migration to the cortex is the distal upper limb. The ectodermal cells of the fetal upper limb migrate to form the hand skin during the fourth and fifth months of gestation (first two-thirds of the second prenatal trimester). Discrepancies in hand morphology between two identical (monozygotic [MZ]) co-twins may be temporal markers, that is, the "fossilized" evidence of various ischemic and other nongenetic insults that may have affected one fetus more than his MZ co-twin during that early part of the second trimester. In twins, prenatal insults (e.g., ischemia) frequently do not affect both co-twins to the same extent, so we examined seven putative markers of prenatal injury to the hand in 24 MZ twin pairs discordant for schizophrenia or delusional disorder. Compared with well co-twins, the affected co-twins had significantly higher total scores of fourth- and fifth-month dysmorphological hand anomalies.