Longitudinal Genetic Analysis for Loneliness in Dutch Twins

In previous studies we obtained evidence that variation in loneliness has a genetic component. Based on adult twin data, the heritability estimate for loneliness, which was assessed as an ordinal trait, was 48%. These analyses were done on loneliness scores averaged over items (‘I feel lonely ’ and ‘Nobody loves me’) and over time points. In this article we present a longitudinal analysis of loneliness data assessed in 5 surveys (1991 through 2002) in Dutch twins (N = 8389) for the two separate items of the loneliness scale. From the longitudinal growth modeling it was found sufficient to have non-zero variance for the intercept only, while the other effects (linear, quadratic and cubic slope) had zero variance. For the item ‘I feel lonely ’ we observed an increasing age trend up to age 30, followed by a decline to age 50. Heritability for individual differences in the intercept was estimated at 77%. For the item ‘Nobody loves me ’ no significant trend over age was seen; the heritability of the intercept was estimated at 70%. Loneliness can be described as consisting of feelings of social isolation and dissatisfaction with one’s social relationships. There is substantial evidence that loneliness is at the heart of a constellation of socioemotional states, which include self-esteem, mood, anxiety, anger, optimism, fear of negative evaluation, shyness, social skills, social support, dysphoria, and sociability (see e.g., Berscheid & Reis