BackgroundChildhood neglect is more common within low-income families and can have long-term effects on mental health. Despite this, the extent to which it can mediate the well documented longitudinal inverse relationship between childhood socio-economic position (SEP) and adult affective symptoms is yet to be investigated. MethodData (9595 males and 8959 females) from participants of the National Child Development Study (NCDS) were used to investigate the extent to which prospectively measured neglect mediates the relationship between SEP (age 11) and affective symptoms (ages 23 and 50). ResultsNeglect partially mediated the relationship between childhood SEP and affective symptoms at ages 23 (b = -0.02, [-0.02, -0.02]) and 50 (b = -0.02, [-0.02, -0.01]), after controlling for other family-related adversities. In addition, gender moderated the direct effect of SEP on affective symptoms at both ages 23 (b = -0.06, t = -4.87, [-0.08, -0.03]) and 50 (b = -0.05, t = -3.86, [-0.07, -0.02]), with the relationship being stronger for females; but did not moderate the indirect effect of neglect at either age 23 (b = 0.01, t = 1.09 [-0.01, 0.02]) or 50 (b = 0.00, t = -0.60 [-0.02, 0.01]). ConclusionsNeglect in childhood should be viewed as having serious implications for the mental health of both men and women. Greater investments into social support interventions that reduce incidences of neglect are also warranted.