Three’s a crowd: Having more than 2 kids linked to weaker brain function

YouTube video

NEW YORK — Everything in moderation — even kids? Researchers from Columbia University and Université Paris-Dauphine report having more than two kids may have a negative impact on late-life cognition. The study shows that older parents with just two children appeared sharper cognitively than those with three.

The connection between kids and cognition was particularly strong among parents in northern Europe. This is noteworthy because, in those countries, having a lot of children usually decreases financial resources without necessarily improving social resources.

While prior studies have focused on the effect of other factors, like education or career choices, on lifelong cognitive outcomes, this is the first project ever to investigate the influence of high fertility.

“Understanding the factors that contribute to optimal late-life cognition is essential for ensuring successful aging at the individual and societal levels—particularly in Europe, where family sizes have shrunk and populations are aging rapidly,” says Vegard Skirbekk, PhD, professor of population and Family health at Columbia Mailman School, in a university release.

“For individuals, late life cognitive health is essential for maintaining independence and being socially active and productive in late life. For societies, ensuring the cognitive health of the older population is essential for extending work lives and reducing health care costs and care needs,” adds Eric Bonsang, PhD, professor of economics at the Université Paris-Dauphine.

More mouths to feed leads to less money

To investigate whether or not having three or more children versus two children affects late-life cognition, study authors analyzed data provided by the Survey of Health, Aging and Retirement in Europe (SHARE). Featuring representative samples of the older populations across 20 European countries and Israel, SHARE was an ideal match for this project. Each individual was at least 65 years-old and had at least two biological children.

Via a series of complex econometric methods, the research team was able to successfully disentangle various causal relationships from simple associations. In simpler terms, the analysis found that having three or more kids (as opposed to just two) is related to worse late-life cognition. This held up among both moms and dads.

Why do more kids lead to potential cognitive decline? Researchers can’t say for now but point to a few different possibilities and contradictions.

To start, more kids mean spending more money — which leads to a lower overall family income and increased chances of falling below the poverty line. Such a sequence of events would lower the standard of living for all family members, not to mention cause constant financial anxiety. All of this, hypothetically, can contribute mightily to late-life cognition drop offs.

Having more kids is also causally related to women’s lower labor market participation, fewer hours worked, and lower earnings. That means, in comparison to retirement, remaining on the workforce positively affects cognitive functioning in both men and women.

More kids, less me-time

All of the unavoidable stress that comes along with parenthood can potentially influence cognition as well. Parents with more kids are more likely to be stressed, have less relaxation time, and often complain of sleep deprivation.

What about the social aspects of a family? Paradoxically, having more kids should decrease one’s risk of social isolation as they grow older. More calls, texts, and time spent with loved ones can go a long way toward keeping an aging mind sharp.

“The negative effect of having three or more children on cognitive functioning is not negligible, it is equivalent to 6.2 years of aging,” Dr. Bonsang notes.

“Given the magnitude of the effect, future studies on late-life cognition should also examine fertility as a prognosticator alongside more commonly researched predictors, such as education, occupational experiences, physical exercise, and mental and physical health,” Dr. Skirbekk concludes.

“In addition, future studies should address the potential effects of childlessness or having one child on late-life cognition. We also need more information on the types of interactions, supports, and conflicts that occur between parents and children, which may influence cognitive outcomes.”

The study is published in the journal Demography.