I am looking at papers which have intriguing data. Let’s start with Archives of General Psychiatry, where power and his colleagues have examined the fertility ratios for six psychiatric disorders in all people born in Sweden between 1950 and 1970.

They conclude:

To our knowledge, this is the first time the fitness of relatives has been examined for individuals with these psychiatric disorders (other than schizophrenia and bipolar disorder). Across disorders, affected men had a consistently greater reduction in fecundity than affected women. A similar sex difference was observed among siblings: sisters of individuals with psychiatric disorders had more children than their brothers. The degree of fecundity reduction in affected individuals and the associated increase in the fecundity among siblings differed by disorder, which suggests that different types of psychiatric disorders are under different selection pressures.

This work cannot be done in countries that do not allow data mining of health records. There is a tradition in Scandinavia of treating all health records as if they are one large case register. A similar design in NZ would require you manually checking and cross checking data from a series of databases — and until recently asking every person individually for access to their health records. We have new provision for audits that may allow this kind of work to be done — but only in areas where there are regional databases. There is no national database.

The Canadians and Americans, however, have good gene-banks. Ernst and others report in the Archives on a five cases of BDNF abnormalities found in a paediatric gene base 38 000 probands. They suggest that BDNF deletion is associated with pain insensitivity, obesity, and psychological disturbance.

Previous reports identified single cases with large deletions encompassing BDNF or cases with BDNF deletions and WAGR syndrome, where 1 study identified 4 different subjects with WAGR syndrome with behavioral disturbances.The current study included more than 38 000 probands collected internationally and found 5 subjects with BDNF deletions with heterogeneous, but always psychiatric, phenotypes. Despite being the most extensive study to date of the role of BDNF in psychopathology, this study should be considered supportive of the role of BDNF in psychopathology and not unequivocal, because the critical region included 2 other potentially causative genes affected in all BDNF deletion cases. Nonetheless, animal data and analysis of the function of these 2 genes in the critical region strongly suggest that BDNF hemizygosity leads to psychopathology.

The biology of psychosis is becoming more interesting as time proceeds.  One hopes that (a) people will start realizing that most psychiatric disorders have biological consequences and (b) find medications that affect BDNF that are not also either toxic or drugs of abuse.