Eight-Year Trajectories of Late-Life Loneliness and Incident Dementia: A Nationally Representative Cohort Study

Some older adults with loneliness might have transient loneliness, followed by full remission, while others might have persistent loneliness. Such different courses might differ in predicting the risk of dementia, but most previous studies assessed short-term loneliness at a single time point, ignoring the long-term changes of loneliness. This study aimed to explore the association between 8-year trajectories of late-life loneliness and incident dementia.Data were from the English Longitudinal Study of Ageing (waves 2-9). This study included 6,722 older adults measured for loneliness greater than or equal to three times from wave 2 (2004-2005) to wave 6 (2012-2013) and free from dementia in wave 6. Loneliness was assessed using the short 1980 version of the University of California, Los Angeles Loneliness Scale. Group-based trajectory modeling was used to explore loneliness trajectories during waves 2-6. Cox proportional hazard models were used to investigate the association of loneliness trajectories with incident dementia during waves 6-9.Five distinct loneliness trajectories were identified: long-term low, persistently decreasing, persistently increasing, long-term moderate, and long-term high. Compared with long-term low loneliness, the HRs (95% confidence intervals) for persistently decreasing, persistently increasing, long-term moderate, and long-term high loneliness were 1.29 (0.83-2.00), 1.55 (1.04-2.31), 1.56 (1.03-2.38), and 3.35 (1.89-5.91), respectively.The elderly show distinct patterns of loneliness over time, which cannot be captured by a single assessment of loneliness. The elderly with long-term loneliness and persistently increasing loneliness might be the high-risk group for dementia. Further studies are needed to determine whether reducing loneliness can prevent dementia.