Age is the most important risk factor for loneliness, which peaks just prior to the peak age of onset for psychotic disorders; contrary to expectations, it declines thereafter over the lifespan

Shovestul, Bridget, Jiayin Han, Laura Germine, and David Dodell-Feder. 2019. “Risk Factors for Loneliness: The High Relative Importance of Age Versus Other Factors.” PsyArXiv. October 11. doi:10.31234/osf.io/t8n2h

Abstract
Background: Loneliness is a potent predictor of negative health outcomes making it important to identify risk factors for loneliness. Though extant studies have identified characteristics that are associated with loneliness, less is known about the cumulative and relative importance of these factors, and how their interaction may impact loneliness. Thus, here, we investigate risk factors for loneliness.

Methods: 4,885 individuals ages 10-97 years from the US completed the three-item UCLA Loneliness Survey on TestMyBrain.org. Using census data, we calculated the population and community household income of participants’ census area, and the proportion of individuals in the participant’s census area that shared the participant’s demographic characteristics (i.e., sociodemographic density). We evaluated the relative importance of three classes of variables for loneliness risk: those related to the person (e.g., age), place (e.g., community household income), and the interaction of person X place (sociodemographic density).

Results: We find that loneliness is highly prevalent and best explained by person (age) and place (community household income) characteristics. Of the variance in loneliness accounted for, the overwhelming majority was explained by age. On age, loneliness peaks at 19 years, and declines thereafter. The congruence between one’s sociodemographic characteristics and that of one’s neighborhood had no impact on loneliness.

Conclusions: Age appears to be the most important risk factor for loneliness, which peaks just prior to the peak age of onset for psychotic disorders, and, contrary to popular belief, declines thereafter over the lifespan. These data may have important implications for public health interventions.