Dopamine, novelty seeking and Parkinson’s disease

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Pdns

I am presently reading the popular science book Living with our genes: why they matter more than you thing, – a book about behavior genetics by Dean Hamer and Peter Copeland.

 

So far I have reach chapter 1: “Thrills: getting high on life”. There researcher Hamer and writer Copeland recount research on exploratory behavior, novelty seeking, Parkinson’s disease and dopamine.

 

Back in the 1990s Hamer was in one of the groups giving evidence for that the personality trait novelty seeking was associated with genetic variation in the third exon of the DRD4 gene with the article Population and familial association between the D4 dopamine receptor gene and measures of novelty seeking and the book is optimistic about what genes can tell about personaltity. On page 47 in my paperback version he writes:

The bottom line is that the D4DR gene says something about the probability a person will be a high or low novelty seeker, but it alone is not enough to predict the score.

Working with personality genetics in the Brede Wiki for Personality Genetics I am more pessimistic. A 2008 meta-analysis shows that the specific genetic variation examined in the 1990s (DRD4 Exon 3) may have zero effect. Another variation in the gene (C-521T) has though showed some effect. This is also what I see in my database with the few studies I have entered.

 

Another issue issue noted by Hamer and Copeland is a relation between Parkinson’s disease and novelty seeking: patients are thought to have lower novelty seeking score than normal control subjects. I have now entered a number of such studies in the Brede Wiki. The meta-analysis on the correlation between Parkinson’s disease and novelty seeking has shown an effect. The support for the hypothesis is not unequivocal though. There is now a fair deal of variation between the studies. The p-value for the heterogeneity is way low and the confidence interval for the random effects meta-analytic effect sits around zero (see plot). This could be due to different/no treatments of the patients, which I haven’t examined further.

 

My opinion is that one should be careful about giving strong statements in this behavioral genetics field. Effects which were clear in initial studies may dilute with further studies.

(correction 14:14: language correction)

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