The observation of a high degree of heritability of brain structure is reinforced by the preliminary findings regarding the effects of genetic polymorphisms on brain structure within healthy populations (Glahn, Thompson, & Blangero, 2007; van Haren et al., 2008). Brain-derived neurotrophic factor (BDNF) is a gene that has been linked with susceptibility to schizophrenia, and has also shown effects on brain morphometric features in healthy controls (Agartz et al., 2006; Ho et al., 2006). The disrupted in schizophrenia 1 (DISC1) gene, another susceptibility gene for schizophrenia (Porteous, Thomson, Brandon, & Millar, 2006), was recently shown to be associated with decreased gray matter volumes in the prefrontal and anterior cingulate regions in both patients with schizophrenia and healthy volunteers (Szeszko et al., 2007). However, studies of effects of single genetic polymorphisms are often negative (van Haren et al., 2008). One of the reasons for this may be lack of attention to the role of interaction with the environment in gene expression. Another consideration is that genes do not act in isolation, particular in the generation of complex traits such as brain volumes, and so statistical methods that are able to model the effects of multiple genes simultaneously may prove more informative.
