Childhood loneliness may have enduring consequences on cognitive health

Childhood loneliness appears to contribute to an increased risk of cognitive decline and dementia in middle and later adulthood, even in the absence of adult loneliness, according to a study.

Researchers used data from the China Health and Retirement Longitudinal Study. They identified 13,592 participants (mean age 58.34 years, 52.8 percent female), with a maximum follow-up of 7 years, for inclusion.

Childhood loneliness was defined as self-reported frequent feelings of loneliness and the absence of close friendships before age 17 years. Adult loneliness was determined using a single item from the Centre for Epidemiological Studies Depression Scale.

Outcomes included cognitive function (evaluated using measures of episodic memory and executive function) and dementia (defined as coexisting cognitive and functional impairments or a self- or caregiver-reported physician diagnosis of dementia).

Of the participants, 6,525 (48 percent) experienced possible childhood loneliness, and 565 (4.2 percent) reported childhood loneliness. Compared with controls who did not experience childhood loneliness, those who did had significantly faster cognitive decline (β, −0.03 SD per year, 95 percent confidence interval [CI], −0.05 to −0.02). Similarly, those who experienced possible childhood loneliness showed accelerated cognitive decline (β, −0.02 SD per year, 95 percent CI, −0.02 to −0.01).

Childhood loneliness was also associated with a 41-percent increased risk of dementia (hazard ratio, 1.41, 95 percent CI, 1.03–1.93).

The associations persisted in analyses controlled for adult loneliness and restricted to participants without adult loneliness. While adult loneliness mediated 8.5 percent of the association between childhood loneliness and cognitive decline and 17.2 percent of the association between childhood loneliness and dementia, it did not significantly modify these associations.