Social isolation during adulthood is linked to an older estimated brain age, according to new research published in Psychological Medicine. The study underscores the importance of maintaining social connections for brain health.
The researchers were motivated by the recognition that social isolation has been linked to adverse health outcomes, including cardiovascular disease, depression, inflammation, and even premature death. They wanted to better understand the potential effects of social isolation on the brain.
“I am interested in the social determinants of health and well-being which include social isolation or the lack of social contact. Being socially connected is vital as it has effects which are embedded in the mind and body, with major consequences for our lives,” said study author Roy Lay-Yee, a senior research fellow at the University of Auckland.
To conduct the study, the researchers used data from the Dunedin Multidisciplinary Health and Development Study, an ongoing longitudinal investigation of a complete birth cohort in Dunedin, New Zealand, born over a one-year period from April 1, 1972 to March 31, 1973. The study included assessments at multiple ages, from childhood (ages 5-11) to adulthood (ages 26-38), tracking the participants’ social isolation status, and measured brain health at age 45.
The researchers classified study participants into four different groups based on their patterns of social isolation from childhood to adulthood.
Never isolated: These individuals had not experienced significant social isolation, either in childhood or adulthood. They consistently had social connections and interactions throughout their lives.
Child-only isolation: These individuals experienced social isolation during their childhood years but not in adulthood. This means they faced periods of lacking social connections and interactions while growing up, but later in life, they were able to establish social relationships.
Adult-only isolation: Individuals in this group did not experience social isolation during their childhood but became socially isolated in adulthood. This suggests that they had a social network during their early years, but as adults, they faced periods of lacking social connections and interactions.
Persistent child-adult isolation: Individuals in this group experienced social isolation both during their childhood and throughout their adulthood. This trajectory indicates a prolonged lack of social connections and interactions that persisted from childhood into adulthood.
Brain age was estimated using an algorithm that combined multiple measures of brain structure obtained through MRI scans when the participants were 45 years old. This algorithm quantified the difference between estimated brain age and the participants’ chronological age, referred to as brain age gap estimate.
If the estimated brain age is higher than the chronological age, it suggests that the brain’s structural characteristics are more similar to those of an older individual. Conversely, if the estimated brain age is lower than the chronological age, the brain’s structural characteristics resemble those of a younger individual.
Lay-Yee and his colleagues also adjusted their analyses for various potential confounding factors. These included socio-demographic factors like sex and socio-economic status, as well as family factors (teen-aged mother, single parent, change in residence, maltreatment) and child-behavioral factors (self-control, worry/fearfulness).
After controlling for these factors, the researchers found that individuals in the adult-only isolation group had an average estimated brain age that was 1.73 years older on average than those who never experienced isolation.
“The take-home message would be to maintain your social relationships which will give you better brain health and cognitive function – and other benefits – in the longer term. Further, try to reach out to others who may be in need of social contact,” Lay-Yee told PsyPost.
The persistent child-adult isolation group also had significantly higher brain age compared to the never-isolated group. However, this relationship became non-significant after adjusting for confounders.
Interestingly, the researchers found that experiencing social isolation during childhood alone (child-only isolation) was not associated with older brain age in mid-adulthood. This result was contrary to their initial hypothesis, which assumed that early exposure to social isolation would have a more significant impact on brain health later in life.
“We were surprised to find that social isolation experienced in childhood did not seem to have a lasting adverse effect on brain age,” Lay-Yee said. “This suggests that it is never too late to improve a person’s social relations.”
While the researchers found an association between social isolation in adulthood and increased brain age, the study design does not provide conclusive evidence to establish a causal relationship. It is possible that older brain age might lead to social isolation, rather than the other way around. In other words, individuals with older brain age might experience cognitive changes that affect their social interactions, leading to increased isolation. To explore this possibility further, the researchers suggested that future studies could involve repeated measurements of both social isolation and brain age over time.
“Our findings show an association between social isolation and older brain age, but we cannot be sure whether the relationship is causal,” Lay-Yee explained. “Further research is needed to confirm whether social isolation does indeed lead to older brain age and what the mechanisms might be.”
The study, “Social isolation from childhood to mid-adulthood: is there an association with older brain age?“, was authored by Roy Lay-Yee, Ahmad R. Hariri, Annchen R. Knodt, Ashleigh Barrett-Young, Timothy Matthews, and Barry J. Milne.
(Note: The original headline incorrectly referred to loneliness rather than social isolation. Loneliness is an emotional state, while social isolation is an objective state. It’s possible for a person to be socially isolated without feeling lonely, and conversely, a person can feel lonely even when they are not socially isolated.)