Cardiovascular diseases (CVD) remain an important cause of death worldwide. Psychological factors such as loneliness and depression have been identified as possible CVD risk factors. Prior research showed that neuroticism moderates the relationship between depression and CVD, but its role in the relation between loneliness and CVD is unknown. Therefore, the present paper aimed to investigate whether neuroticism also moderates the relationship between loneliness and CVD. Two hypotheses (H) were formulated: loneliness will be positively associated with CVD (H1), and neuroticism will moderate the relationship between loneliness and CVD such that this relationship becomes more strongly positive in those with higher neuroticism compared to those with lower neuroticism (H2). 

Additionally, loneliness and social isolation are similar yet conceptually distinct concepts, therefore secondary analyses tested whether the results are specific to loneliness or also generalize to social isolation. A sample of 157,286 participants from the UK biobank was used for analyses and the hypotheses were tested by means of three logistic regression models, each adjusted for covariates. These models tested the link between CVD and respectively (1) loneliness, (2) neuroticism, and (3) loneliness, neuroticism, and their interaction. Analyses were then replicated using social isolation as the predictor instead of loneliness. Results indicated that those who were lonely were 31% more likely to have CVD compared to those who were not lonely, but neuroticism did not moderate this relationship.

Furthermore, while social isolation was not associated with CVD, an interaction with neuroticism was observed: socially isolated people who were more neurotic had 2% lower odds of having CVD compared to socially not isolated people who were less neurotic. Concluding, loneliness is associated with higher odds of having CVD, thus interventions are advised to target loneliness as a modifiable psychological risk factor for CVD. Since the loneliness effect found was not very large, immediate physical medical attention would not be necessary for lonely patients, but monitoring prognosis and keeping an eye out for potential signs of cardiovascular problems is recommended.