Challenging the assumption that aging inevitably brings cognitive and functional decline, a nationally representative longitudinal study of US adults aged 65 years or older found that 45.15% of participants showed cognitive and physical improvement over up to 12 years of follow-up. The analysis also found that holding positive beliefs about aging was associated with a greater likelihood of those improvements. The findings were published in the journal Geriatrics.

“The prevailing narrative that aging is a period of inevitable and universal decline needs to be reconsidered,” said lead author Becca R. Levy, PhD, professor of social and behavioral sciences at the Yale School of Public Health, New Haven, Connecticut, in an interview with News Medical Life Sciences. According to her, “Improvement in later life is not rare; it is common and should be incorporated into our understanding of the aging process.”

The research team analyzed data from the Health and Retirement Study, a US national longitudinal cohort of older adults with biennial assessments, followed for up to 12 years. Participants were eligible if they completed a baseline assessment of beliefs about aging and had at least one follow-up evaluation of cognitive or physical function.

The cognitive cohort included 11,314 participants, with a mean starting age of 68.12 years, whereas the gait speed analysis included 4638 participants, with a mean age of 74.03 years. The average follow-up time was about 8 years, extending up to 12 years.

Cognitive function was assessed using the Telephone Interview for Cognitive Status (TICS), a globally validated instrument for cognitive screening via telephone interview that evaluates memory, delayed recall, and mathematical skills. Physical function was measured by gait speed, which is considered a global marker of functional performance and often described as the “sixth vital sign” because of its association with hospitalization, disability, and mortality risk in older adults.

Beliefs about aging were measured with the Attitude Toward Own Aging subscale of the Philadelphia Geriatric Center Morale Scale, which assesses positive and negative perceptions of aging, with higher scores indicating more positive views of later life. Statistical models were adjusted for age, sex, race and ethnicity, depressive symptoms, sleep problems, education, marital status, cardiovascular disease, diabetes, social isolation, and follow-up time.

Results

Among participants with available cognitive and physical measures, 45.15% showed improvement in at least one of the assessed domains. When analyzed separately, 31.88% showed cognitive improvement, and 28% showed improvement in gait speed.

When participants who remained unchanged were included, 51.06% had stable or improved cognition, and 37.56% had stable or improved gait speed.

Even when more conservative criteria were applied, findings were consistent: 22.5% showed cognitive improvement, and 26.71% showed clinically meaningful physical improvement. Moreover, among those classified as having normal performance at baseline, 27.74% showed cognitive improvement and 23.08% showed physical improvement over follow-up.

Positive beliefs about aging were associated with a greater likelihood of cognitive improvement (odds ratio [OR], 1.04; 95% CI, 1.00-1.08; P = .049) and improvement in gait speed (OR, 1.09; 95% CI, 1.02-1.17; P = .018) after adjustment for covariates.

Levy also noted that the results can be missed when only population averages are analyzed. “If we look only at the mean, what we see is decline. But when we analyze individual trajectories, we find that a substantial proportion of older adults improve over time,” she said.

Indeed, when participants were analyzed as a homogeneous group, the mean change was a decline of 1.39 points on the TICS and a reduction of 11.69 cm/sec in gait speed. However, accounting for heterogeneity in individual trajectories revealed that a substantial subset experienced functional improvement.

The correlation between cognitive improvement and gait speed improvement was low (r = 0.09), and only 44% of participants who improved cognitively also improved physically.

Findings Challenge Prevailing View

The authors emphasize that the findings challenge the dominant definition of aging as a process solely associated with functional loss. Conceptual reviews often describe aging as “a process of loss,” and population surveys show that many people — including some healthcare professionals — believe cognitive decline is inevitable.

However, by examining individual trajectories, the study showed that a significant portion of older adults experience improvement over time.

In addition, the study is the first to show that positive beliefs about aging are associated with improvement, not just with lower rates of decline. These results build on prior evidence that positive age perceptions are linked to better cognitive and physical function over time, improved recovery after disability or mild cognitive impairment, and better functional outcomes after interventions that reinforce positive ideas about aging.

The authors suggest the effect may operate through biological and behavioral mechanisms. A prior study found associations between negative age beliefs and biomarkers of Alzheimer’s disease, including greater plaque and tangle deposition and smaller hippocampal volume. These data raise the hypothesis that positive beliefs might have the opposite effect, promoting neural plasticity and functional reserve in aging.

Another notable finding was that most participants who improved did so in only one domain — cognitive or physical — which contrasts with the assumption that these processes progress in parallel in later life. This suggests different mechanisms may underlie trajectories of functional aging.

The perception that older adults do not experience cognitive or physical improvement may be leading to underuse of preventive and rehabilitative strategies. Thus, demonstrating functional improvement in a significant proportion of individuals suggests health promotion interventions can be effective even at advanced ages.

Limitations noted by the authors include the absence of direct measures of neuronal and muscular plasticity, which prevents identification of the biological mechanisms underlying the observed improvement. The researchers also highlighted the need to assess other cognitive domains beyond the global measure used and to replicate analyses in populations with greater ethnic diversity. Although the sample is nationally representative, additional studies in other cohorts are needed to confirm generalizability.

Implications and Future Prospects

The main conclusion of the study is that aging should be redefined to encompass the possibility of functional improvement. Awareness of that potential could boost older adults’ self-efficacy, encourage engagement in healthy behaviors, and prompt health professionals to offer preventive and rehabilitative interventions. Moreover, strategies to promote positive beliefs about aging may be a modifiable factor with clinically meaningful impact.

Future research should examine biomarkers of improvement, the neurobiological mechanisms involved, interventions that can modify age-related beliefs, and their effects on clinical outcomes.

This story was translated from Medscape’s Portuguese edition.