Understanding loneliness in emerging adulthood: A mixed methods approach

Introduction. Loneliness is prevalent during young or emerging adulthood and is an important public health issue given it has been associated with poorer mental and physical health outcomes. The overall aim of the present research was to advance the understanding of loneliness in emerging adulthood using a mixed-methods approach.

Methods. This thesis reports on four studies. Study 1 (scoping review) provided a descriptive overview of the literature on loneliness in emerging adulthood to identify issues with the current research and priorities for future studies. Seven electronic databases were searched for articles focused on loneliness in emerging adulthood (18-25 years) published from 2016 to 2021. Study 2 explored the views and experiences of loneliness from the perspective of emerging adults in Ireland through semi-structured interviews (N = 27). Study 3 analysed three annual waves of loneliness data in a sample of youth (N = 827) from the UK Household Longitudinal Study to explore trajectories of loneliness and examine their association with psychological distress at final follow-up. Finally, Study 4 conducted a conceptual replication of Study 3 to determine if the findings were robust when using a single-item direct measure of loneliness. Additionally, it compared loneliness trajectories identified with the single- and multi-item scales to explore if participants were classified differently depending on the measurement method.

Results. Study 1 included 201 studies on loneliness in emerging adulthood and identified three key issues in the literature that limit the understanding loneliness in this group: first, a significant proportion of included studies lacked a clear, explicit conceptualisation of loneliness. Second, there were few qualitative explorations of loneliness. Third, most included studies were cross-sectional and conducted with convenience samples of university students. To address the gap in qualitative research exploring subjective experiences of loneliness, the qualitative analysis in Study 2 identified two key themes that described loneliness and its causes: loneliness and development “a part of growing up”, and expectations about a typical emerging adult’s life “that’s how my life should be”. The findings underscored that at least some loneliness may be transient and highlighted a range of loneliness experiences during emerging adulthood. Study 3 built on these findings using k-means longitudinal analysis to identify four participant clusters representing distinct patterns of loneliness: stable low, stable high, moderate decreasing, and low increasing loneliness trajectories. Compared to stable low loneliness, stable high and low increasing loneliness clusters were significantly associated with psychological distress following adjustment for confounding variables. Finally, Study 4 extended the results of Study 3 by providing evidence that significant associations identified with the multi-item scale were robust to the use of the single-item loneliness measure.

Conclusion. Overall, the contributions of this thesis are four-fold. First, this research identifies issues with the literature on loneliness in emerging adulthood and provides recommendations for research, including the need for a clear conceptualisation of loneliness in studies. Second, findings suggest that some loneliness is normative in the context of development and influenced by expectations of emerging adulthood, contributing to the understanding of loneliness during this life stage as a complex, subjective experience. Third, using two loneliness measures, this thesis provides evidence of a persistent, relatively high loneliness trajectory during emerging adulthood that is associated with psychological distress. Fourth, the findings provide support for the use of single-item loneliness measures in population-based surveys among emerging adults.