Genetics of schizophrenia in the South African Xhosa.

Africa, the ancestral home of all modern humans, is the most informative continent for understanding the human genome and its contribution to complex disease. To better understand the genetics of schizophrenia, we studied the illness in the Xhosa population of South Africa, recruiting 909 cases and 917 age-, gender-, and residence-matched controls. Individuals with schizophrenia were significantly more likely than controls to harbor private, severely damaging mutations in genes that are critical to synaptic function, including neural circuitry mediated by the neurotransmitters glutamine, γ-aminobutyric acid, and dopamine. Schizophrenia is genetically highly heterogeneous, involving severe ultrarare mutations in genes that are critical to synaptic plasticity. The depth of genetic variation in Africa revealed this relationship with a moderate sample size and informed our understanding of the genetics of schizophrenia worldwide.

Hemispheric differences in preferred modes of information processing and the aging process.

The notion of "preferred modes of information processing" as indexed by direction of lateral eye movements during information processing, and the finding of significant declines in "fluid" as compared to "crystallized" intelligence as a function of the aging process, are related in this paper. Results suggest differential declines in information processing abilities as a function of preferred mode of information processing in older subjects. Old right movers perform significantly better than old left movers on tasks tapping both fluid and crystallized intelligence. Old left movers perform significantly more poorly on these tasks when compared to young left movers, while no differences between young and old right movers obtain. The results suggest that old persons may be more at the mercy of their preferred mode of information processing than young subjects and that those who prefer to process information in their right hemisphere are more detrimentally affected by this preference.

An in vivo and in vitro study of an aging-related neuron cytoplasmic-binding antibody in male Fischer rats.

Fischer 344 male rats showed a low average level (less than ++) of in vivo as well as in vitro neuron binding antibody at 3, 15, and 26 months. However, a significant increase with age in average intensity of binding was observed with both the in vivo and the in vitro conditions. If a criterion of ++ is used as an antibody binding level likely to have biological consequences, the percent of in vivo cases showing foci of ++ or greater intensity also rises with age from 20 to 80%; a criterion of +++ gives an in vivo rise with age of only from 10 to 20%. The in vitro incidence with the ++ criterion is already 80% at three months and rises to 90%; with the +++ criterion the incidence with age rises from 20 to 80%. No evidence was obtained to support the concept that there is a weakening of the blood-brain-barrier in 26 month rats either by the systemic injection of trypan blue or by a comparison of intensity of antibody binding between extra- and intra-barrier neurones.