Sharper reasoning skills in teen years tied to lower dementia risk later in life

by Sanjukta Mondal, Medical Xpress

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edited by Lisa Lock, reviewed by Robert Egan

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Could the way we think in our 20s offer clues about our risk of dementia decades later? Large population studies suggest that people who perform better on thinking ability tests in adolescence or young adulthood are less likely to develop dementia later in life. However, cognitive performance in early adulthood is shaped by more than thinking ability alone; it can also reflect education, life experiences and family environment. This makes it difficult to determine whether scores on cognitive tests are a reliable indicator of future dementia risk.

In a recent study published in Alzheimer's Research & Therapy, researchers tested children's reasoning at age 13, before major differences in schooling and social pathways emerged. Lower cognitive scores in youth are also linked to higher risks of cardiovascular disease and diabetes in adulthood, so researchers examined whether early reasoning ability was directly linked to dementia risk, independent of these diseases.

After following more than 10,000 Swedish individuals from sixth grade to 60 years later, researchers found that children who scored higher on inductive reasoning tests at age 13 went on to have a lower risk of dementia decades later. This link held up even after accounting for parents' education, the participants' own education in midlife, and major physical illnesses, including cardiovascular disease and diabetes.

Rewinding to childhood

Dementia doesn't just erode memory. It can also reshape how a person thinks, communicates, feels and behaves, making everyday tasks harder to manage. The global burden of dementia is larger than ever, and it's expected to rise because of an aging population. In 2021, 57 million people were living with dementia, making it the seventh-leading cause of death worldwide and a major cause of disability and dependency among older people.

Dementia doesn't develop in isolation. Heart health, diabetes, education and even how the brain develops in early childhood all play a role over a lifetime. This led scientists to wonder whether cognitive test scores from someone's youth could offer early clues about their dementia risk decades later.

They did find a possible association: Higher cognitive ability in late adolescence and early adulthood lined up with lower dementia risk, but there was a catch. By that age, one's thinking ability was already shaped by years of education and experience, making cause and effect difficult to separate.

Also, most existing evidence linked long-term dementia risk to a single, general intelligence score rather than specific cognitive tasks.

In search of a solid link, the team tested 10,539 Swedish 13-year-olds born in 1948, who took cognitive tests in sixth grade in 1961 measuring three distinct mental abilities: inductive reasoning, verbal ability and spatial ability. The researchers then tracked these participants through adulthood, spanning six decades of follow-up into November 2025. Rather than relying on self-reported health, they linked childhood test results directly to Swedish national hospital and death registers, extracting diagnoses of dementia, cardiovascular disease, diabetes and other major conditions.

Protective effect of a skill

Children who scored higher on the inductive reasoning number-series test at age 13 grew up to have a lower risk of dementia. Each additional point on that test was linked to roughly a 2% drop in dementia risk decades later. The other two tests, verbal ability and spatial ability, didn't show the same pattern and failed to predict dementia risk over the long run on their own.

This link between childhood reasoning and dementia held up even after accounting for parental education and the participants' midlife education level. What stood out was that once childhood reasoning ability was factored in, midlife education no longer showed an independent effect on dementia risk.

The researchers noted that while these findings can't prove causality, they build on earlier evidence linking early-life cognitive function to later disease risk. Future long-term studies can take this further and explore whether supporting healthy cognitive development in childhood is one of the best long-term investments against dementia.

Written for you by our author Sanjukta Mondal, edited by Lisa Lock, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.

Publication details

Kristine Beate Walhovd et al, Childhood inductive reasoning, cardiovascular and cardiometabolic morbidity and dementia risk – a population representative cohort study across six decades, Alzheimer's Research & Therapy (2026). DOI: 10.1186/s13195-026-02179-1

Journal information: Alzheimer's Research & Therapy

Key medical concepts

DementiaCardiovascular DiseasesDiabetes

Clinical categories

NeurologyHealthy agingChildren's health Who's behind this story?

Sanjukta Mondal

Master's in Chemistry. Freelance science journalist and communicator. Published in Chemistry World, BioSpace, and The Hindu. Full profile →

Lisa Lock

BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021. Full profile →

Robert Egan

Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →

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