Further, the developmental link between phenotypes is not always straightforward. Adult expression of symptoms/traits often do not map directly onto their expression in childhood, due to numerous biological, psychological, and social changes that take place throughout development. For example, AUDs in adults are characterized by impairments in social and occupational roles that children and adolescents simply do not have, as well as excessive consumption of alcohol at levels that are almost impossible for a young person to achieve given social and legal restrictions on access. Early initiation and moderate consumption are therefore a better indicator of deviant/problem behavior in young children, though they are normative behaviors in adults (Thompson et al., 2014). Similarly, mood and anxiety disorders in children often manifest with physiological rather than cognitive symptoms before they have developed the ability to interpret complex feelings (Ollendick et al., 1994). Post-GWAS studies can use this knowledge to test how genetic influences on late stage outcomes manifest in the earlier progression of traits and behaviors leading up to them. Such knowledge can point to developmental periods and processes (e.g. neurodevelopment, puberty, shifting social roles) that are most relevant for promoting changes in behavior.
