title: Our neglect of the normal variation is linked to a reluctance to accept multifactorial inheritance and the role of environment.
abstract: One of the most surprising evolutionary discoveries is that wild species similar to human contain a vast reservoir of variability. Why are we persistently reluctant to discuss normal variation in brain structure and function and label any deviation pathological? Despite the failure of Mendelian Genetics to solve the genetic puzzle in psychiatry, we refuse to discuss multifactorial inheritance and the role of environmental factors. Rising living conditions (high protein diet) accelerate maturation, lower pubertal age, shift body-built toward more weight for height and cerebral excitability toward higher levels. Another environmental factor which has to be provided by diet is marine fat which our brain consists of. It normalizes brain function at all levels of excitability and possibly prevents psychotic episodes if adequately supplied. As part of Human Variation in Growth and Maturation, Schizophrenia and Manic-depressive psychosis are multifactorially inherited and share susceptibility loci. They are localized at the extremes of variation. Excitability, body-built, clinical picture and CNS finding accord with this, their phenotypic characteristics might prove valuable in a hunt for genes not common to both disorders.
authors.affiliation: National Hospital, Rikshospitalet, Oslo, Norway.
authors.forename: Letten F
authors.initials: LF
authors.lastname: Saugstad
mesh_terms: D001921:Brain / Q000033:anatomy & histology / Q000502:physiology; D004777:Environment; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D006801:Humans; D008957:Models, Genetic; D020412:Multifactorial Inheritance; D010641:Phenotype; D011618:Psychotic Disorders / Q000209:etiology