In Dunedin, we used the maltreatment measure described previously (Caspi et al., 2003). Evidence of childhood maltreatment between ages 3 and 11 years was ascertained from five sources. Three sources were prospective: (a) observations by researchers of rejecting mother–child interactions at age 3; (b) parental reports of harsh discipline at ages 7 and 9; (c) multiple changes of the child’s primary caregiver during the first decade of life. Two sources were retrospective: study members’ reports in adulthood of (d) physical and (e) sexual abuse. A cumulative exposure index was derived from the number of maltreatment experiences during the first decade of life; 64% of the cohort experienced no maltreatment, 27% experienced probable maltreatment (1 indicator), and 9% experienced definite maltreatment (2 or more indicators). There was no association between the 5-HTTLPR and childhood maltreatment in Dunedin (χ2(2)=1.67, p=0.80).
