Loneliness, the immune system, and cardiovascular health: A systematic literature review

Objective: Loneliness can have a variety of negative effects on health, such as chronic stress, altered parasympathetic function, pro-inflammatory immune responses, and psychological distress. The aim of this systematic literature review is to investigate the effects of loneliness on health and the direct relationship between loneliness and cardiovascular health, as well as the relationship between loneliness, the immune system, and the cardiovascular system. Methods: The review was conducted by searching Scopus, Web of Science, PubMed, PsycInfo, and PsycArticles between January 2010 and March 2025, the date of the search. We used a combination of the following keywords: (alone OR lonel* OR isolation OR exclusion OR companionship) AND (cardiovascular OR heart OR cardiac) AND (immun* OR inflamm*) AND (psych* OR mental). The quality assessment was conducted using the Critical Appraisal Checklist of the Joanna Briggs Institute. Results: The literature search led to the identification of 23 articles. Loneliness appears to have both direct and indirect negative effects on cardiovascular health. It is associated with inflammation, which in turn affects the cardiovascular system. In addition, the associated negative feelings can have a negative impact on health as they can lead to increased inflammation and negative lifestyle habits such as alcohol consumption and nicotine use, which in turn increase inflammation. Conclusions: From a clinical psychology perspective, it is important to consider loneliness and social isolation as indicators of fragility, which may be related to cultural differences, an unhealthy environment, the unavailability of services, and a lack of opportunities to develop professional and social roles.