mental and somatic health, attrition does not appear to affect twin analyses of mental health [33]. In wave 2, altogether 2284 twins (987 complete pairs and 310 single twins) were re-interviewed approximately 10 years later. Attrition from 1st to 2nd wave was low (82.2% were retained), and a complete breakdown of twin pairs indicated that attrition is unlikely to affect analyses on pertinent PDs [24].
