Genes 2 Brains 2 Mind 2 Me

As I and many other 23andMe participants begin to confront our genetic innards, we will likely ask whether any of the information is predictive.  Can we expect to read-off our genomic information and say, “I have risk for this, this, and this, and so I’ll change my life to compensate ?”  Certainly, in the area of mental health, there are genetic variants that confer bits of risk toward anxiety, depression, cognitive decline etc., but does the raw genomic information – alone – form a basis for diagnosis and proscriptive change?  In most cases, NO.  Rather, the genome is not unlike a plant seed, that will produce full leafy greens in rich soil, but merely a few buds in poor soil.

A great example of this can be seen in the recent paper, “What is an “Adverse” Environment? Interactions of Rearing Experiences and MAOA Genotype in Rhesus Monkeys” by Karere er al. [doi: 10.1016/j.biopsych.2008.11.004].  In this paper, they compared the emotional development of rhesus monkey infants (n=473) who carry different versions of an MAOA promoter polymorphism – so-called ‘low’ vs. ‘high’ transcriptional level alleles – and also who were reared in different social contexts.  Some of the existing literature on MAOA-environment interactions suggests that abuse or neglect during childhood predisposes individuals who carry the ‘low’ allele (this allele leads to less MAOA protein and less catabolism of 5HT and DA).  In this study, the environment was varied according to numbers of social companions and physical size of the neighborhood – (i) a field enclosure with up to 150 mixed adults & children, (ii) corncrib enclosure with 1 adult male, 2-5 females and various child playmates, (iii) mother-only small enclosure, and (iv) no-mother nursury rearing.

Which environment led to the emotional reactivity (anxiety, aggression etc.) that has been previously associated with the MAOA ‘low’ allele?  Interestingly, it was not the wild & wooly ‘field enclosure’ where infants can interact in a rich, species-typical manner.  Rather, it was the MAOA ‘low’ genotypic infants raised in the smaller groups who showed more signs of emotional reactivity, with cage-mother-only-rearing being the most extreme group.  The authors note that this finding may alter our expectations about what type of environment is optimal vs. adverse and suggest that in the smaller enclosures, the relative isolation underlies the development of anxiety.

From a more general perspective, this study raises questions about how we – humans – should interpret our genomic information.  What environmental conditions enhance or protect us from the potential genetic risk we carry?  How did my early rearing interact with my MAOA allele?  Something to discuss on Mother’s Day.