Vulnerability genes or plasticity genes?

Abstract

The classic diathesis-stress framework, which views some individuals as particularly vulnerable to adversity, informs virtually all psychiatric research on behavior-gene-environment (G x E) interaction. An alternative framework of 'differential susceptibility' is proposed, one which regards those most susceptible to adversity because of their genetic make up as simultaneously most likely to benefit from supportive or enriching experiences-or even just the absence of adversity. Recent G x E findings consistent with this perspective and involving monoamine oxidase-A, 5-HTTLPR (5-hydroxytryptamine-linked polymorphic region polymorphism) and dopamine receptor D4 (DRD4) are reviewed for illustrative purposes. Results considered suggest that putative 'vulnerability genes' or 'risk alleles' might, at times, be more appropriately conceptualized as 'plasticity genes', because they seem to make individuals more susceptible to environmental influences-for better and for worse.

Figure 1

Center for Epidemiological Studies-Depression (CESD) scores for female caregivers and non-caregiver controls by 5-HTTLPR genotype (Brummett et al.²⁷).

Figure 2

Proportion of female participants with a high level of depression by environmental risk group and 5-HTTLPR genotype (Eley et al.²⁸).