Some exciting new research has recently hit the scene suggesting that some human beings might be in possession of a special gene that makes them more sensitive than others. No, this does not mean that Jennifer Aniston was right when she said that Brad Pitt was missing a "sensitivity chip." It has nothing to do with hurt feelings or how often you cried throughout season 4 of The Wire. What it does help to determine, however, is how you respond to unfamiliar or uncertain environments. Referred to as the "differential susceptibility hypothesis," scientists have found that "some of the very same genes that under certain environmental conditions are associated with some of the lowest lows of humanity, under supportive conditions are associated with the highest highs of human flourishing."
Rising superstar Rachael Grazioplene and colleagues focused on the cholinergic system– a biological system crucially involved in neural plasticity and learning. Situations that activate the cholinergic system involve "expected uncertainty" such as going to a new country you've never been before and knowing that you're going to face things you've never faced before. This stands in contrast to "unexpected uncertainty", which occurs when your expectations are violated.
The cholinergic system is ideal for observing the differential susceptibility effect because it is more active in situations in which the subject is prepared to learn.
To test their hypothesis, they focused on a polymorphism in the CHRNA4 gene, which builds a certain kind of neural receptor that the neurotransmitter binds to. These acetylcholine receptors are distributed throughout the brain, and are especially involved in the functioning of dopamine in the striatum. Genetic differences in the CHRNA4 gene seem to change the sensitivity of the brain's acetylcholine system because small structural changes in these receptors make acetylcholine binding more or less likely. Previous studies have shown associations between variation in the CHRNA4 gene and neuroticism as well as laboratory tests of attention and working memory.
To study it in action, scientists set up an 8-13 week day camp for 614 children all from the same economic background, but with some children coming from environments where maltreatment (various types of abuse, neglect, etc.) was prevalent and other children coming from normal, non-abusive environments. Researchers then observed that mistreated children with the T/T variation of the CHRNA4 showed higher levels of anxiety, neuroticism and fear when faced with new and uncertain situations than mistreated children with the C allele of the gene. For kids with the T/T variation of the CHRNA4 who came from stable environments, however, new situations were met with curiosity rather than anxiety. The results were the same regardless of race, sex and age.
The T/T type is incredibly rare in the general population and only explains the tiniest percentage (like 1% tiny) of neuroticism, but its discovery and the research into more genes like it could have a profound effect on the way psychologists consider environment in relation to behavior. Recognizing the gene (and those who have it) could help influence a person's trajectory and the way they respond to uncertainty in the future.