Published online by Cambridge University Press: 01 August 2014
After having examined the literature on the subject, the A. presents the study he has carried on 60 twin-pairs with one or both twins suffering from neurosis or psychosis.
In 50 pairs a psychic suffering of neurotic type was present: out of the 20 MZ pairs, 18 were concordant with a percentage of 90%; out the 30 DZ pairs, 13 were concordant 43%.
Although discriminating the various forms and admitting the interference of environmental factors and other somato-psychic and psychogenetic causes, in 50% of the cases an undoubted psychotic and neurotic heredity was ascertained.
In the four pairs suffering from dysthymic psychosis the 3 MZ were concordant and the DZ discordant.
In the four pairs suffering from schizophrenia the MZ pair was concordant while the 3 DZ pairs were discordant.
In the two pairs of uncertain zygosity the concordance could not be extimated due to the death of the cotwin.
Dysthymia seems to be trasmitted as a dominant character and schizophrenia as a recessive.
Both dystymia and schizophrenia may undergo changes of expressivity with phenotypical characters which can be clinically mistaken as psychoneurotic forms.