BMC medicine
Longitudinal associations between loneliness and outcomes of Common Mental Disorders (CMDs): A systematic review and meta-analysis
By Stefanidou T, Li S, Lagan K and 11 others.
Abstract
Background
Loneliness has been increasingly associated with poor mental health outcomes, yet its prognostic role in people with Common Mental Disorders (CMDs) remains unclear. This systematic review aimed to examine whether loneliness is longitudinally associated with mental health outcomes in individuals with CMDs, regardless of treatment status.
Methods
We searched PsycINFO, MEDLINE, Embase and CINAHL from inception to October 2025 for longitudinal studies examining associations between baseline loneliness and CMD outcomes at follow-up. Eligible studies included adults aged 16+ with CMDs. We conducted a narrative synthesis and where appropriate, random-effects meta-analyses for binary depression outcomes reflecting unfavourable course (recurrence, persistence, or non-remission). Study quality was assessed using the Newcastle-Ottawa Scale, and certainty of evidence was evaluated using GRADE. The protocol was registered with PROSPERO (registration number: CRD42023410401).