Community and societal influences on loneliness and social isolation among young adults: A systematic review of observational studies

Loneliness and social isolation are emerging public health concerns among young adults, yet the role of community and societal factors remains poorly understood. Existing research has predominantly focused on individual or interpersonal determinants. This systematic review synthesised observational evidence on community- and societal-level factors associated with loneliness and social isolation among young adults aged 18-30 years. Five databases were searched for observational studies examining place-based community or societal exposures and loneliness or social isolation outcomes. Thirteen eligible studies were identified, and a structured narrative synthesis was undertaken. The exposure variables explored were diverse. Neighbourhood characteristics (including trust, safety, and atmosphere), community participation, cultural and societal norms, and structural conditions demonstrated consistent associations with loneliness. Higher neighbourhood cohesion, safety and belonging were protective, whereas neighbourhood disorder, minority status, perceived discrimination and individualistic cultural orientations were associated with greater loneliness. Evidence for social isolation was sparse and methodologically heterogeneous, though area-level disadvantage and remoteness showed emerging relevance. Most studies were cross-sectional in design, and the way that loneliness and social isolation were measured across studies was heterogenous. Community and societal determinants meaningfully shape young adults' experiences of loneliness, but evidence for social isolation remains limited. Findings highlight the need for longitudinal research, improved consistency in the use of measurement tools, further examination of moderators between individual factors and community influences, which will all contribute to the development of multi-level public health strategies addressing structural and neighbourhood conditions.