Mental health: What you believe about ageing changes how you age

45% of people over 65 improved their cognitive or physical function over a 12-year period. The single strongest predictor of who improved wasn't genetics or lifestyle — it was what they believed about getting older.

Why it matters

Most of us absorb a fairly bleak story about ageing before we ever get old. Dementia is inevitable. Decline is one-directional. The best you can hope for after 65 is slowing the deterioration. This narrative is so pervasive that even the World Health Organisation's assessment tools for older adults don't include a category for improvement — only decline, or no decline.¹

A study published in Geriatrics in 2026 by researchers at Yale University challenged that assumption directly. Using data from the Health and Retirement Study — a nationally representative longitudinal study of more than 11,000 Americans tracked for up to 12 years — Becca R. Levy and Martin D. Slade asked a deceptively simple question: do older people ever actually get better?²

The answer was a clear yes. Among participants aged 65 and older, 45% improved in cognitive and/or physical function over the study period. Cognitive function improved in 32% of participants; walking speed — a measure so predictive of hospitalisation, disability, and mortality that researchers call it the "sixth vital sign" — improved in 28%.³ When you consider that most studies average performance across all participants and declare decline the universal story, hiding these individuals within the aggregate, this is a striking finding.

But the more interesting result was what predicted improvement. Levy and Slade measured participants' age beliefs at baseline using a validated scale — questions exploring whether they felt useful, happy, and capable as they aged — then followed them for up to 12 years. After adjusting for age, sex, education, depression, sleep, cardiovascular disease, and even genetic risk (APOE 4), people with more positive age beliefs were significantly more likely to improve in both cognitive and physical function.²

The mechanism appears to run deeper than motivation. Levy's earlier research found that negative age beliefs were associated with biological markers of Alzheimer's disease — specifically, accumulation of plaques and tangles and reduced hippocampal volume — suggesting that what you believe about ageing influences the brain's biology, not just your behaviour.⁴ The researchers propose a reinforcing loop: positive beliefs lead to better function, which reinforces positive beliefs, which leads to further improvement — a kind of cognitive and physical compounding.

This does not mean believing hard enough will reverse serious illness. The effect sizes are real but modest, and the study cannot tell us whether people improved because of their age beliefs or whether both are driven by some third factor. But the research adds to a substantial body of evidence — across nine meta-analyses — that how you perceive ageing predicts measurable health outcomes, independent of the obvious confounders.⁵

How to build more positive age beliefs

• Notice the narrative you've absorbed. Before you can shift age beliefs, you have to see them. Pay attention to how you talk about your own ageing — "I'm too old for that," "it's all downhill from here" — and whether those statements are conclusions or assumptions. Most are assumptions.
• Actively look for evidence that contradicts the decline story — in data and in people. Nearly half of people over 65 in the Yale study improved cognitively or physically over 12 years, but that finding rarely surfaces because most research reports averages, which hide the improvers within the overall trend. Seek out people in your own life — or in public life — who are improving with age, and recognise them as representative, not exceptional. The story that decline is universal isn't a scientific conclusion; it's a failure to look closely enough.
• Track function, not just age. Objective measures like walking speed, grip strength, VO₂ max, and cognitive test scores tell you what is actually happening in your body — not what the calendar says should be happening. 100 Great Years is built around this principle. Improvement is visible when you measure it.
• Separate chronological from biological age. You have no control over the former and significant influence over the latter. Conflating the two leads to fatalism. Keeping them distinct gives you agency.
• Be selective about the cultural messaging you absorb. Media representations of ageing skew heavily negative and are not representative of population-level data. This includes well-meaning content that frames "healthy ageing" as merely slowing decline. You are allowed to set a higher ambition.
• Consider what you model for others. Age beliefs are partly socially transmitted — we absorb them from the people around us. How you talk about your own ageing, and how you respond to others' ageing, shapes the environment for everyone.
• Look for purpose and contribution as active drivers. Sense of purpose is associated with cognitive preservation across multiple longitudinal studies. It is not a vague wellness concept — it is a measurable variable with measurable health effects. Having a reason to show up mentally makes showing up more likely.⁶
• Apply this to physical health practices, not just mental ones. The Levy study found that positive age beliefs predicted physical improvement — faster walking speed — not just cognitive improvement. The belief that your body can still adapt is a prerequisite for giving it the conditions to do so.

The 100 Great Years perspective

Most health platforms treat ageing as a problem to be managed — a slow erosion to delay for as long as possible. 100 Great Years is built on a different premise: that the trajectory of your later decades is genuinely modifiable, and that the modifications are available to far more people than the dominant narrative suggests. The Levy and Slade research gives scientific grounding to something the platform assumes: that planning to age 100 is not wishful thinking, but a rational orientation toward a body of evidence showing that improvement, not just maintenance, is possible. Your age beliefs are not fixed, and they cost nothing and take no equipment to change. They also appear to compound: better beliefs support better function, which reinforces better beliefs.

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This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before making decisions about your health.