Differential association of step count with depressive and anxiety symptoms in older adults at risk of dementia

Depressive and anxiety symptoms are prevalent among older adults and associated with increased dementia risk. In healthy older adults, higher step counts are associated with fewer depressive and anxiety symptoms; whether this holds in individuals with cognitive concerns (subjective cognitive decline [SCD] or mild cognitive impairment [MCI]) is unknown. In a randomised controlled trial, the 12-month APPLE-Tree group psychosocial lifestyle intervention produced small cognitive improvements but no change in step count.

Objective

To test whether step count was associated with depressive and anxiety symptoms (cross-sectionally and over 24 months), and whether APPLE-Tree increased step count in participants with clinical anxiety or depression.

Methods

We examined cross-sectional and longitudinal (12- and 24-month) associations between step count (two-week average from wrist-worn wearables) and depressive and anxiety symptoms (Hospital Anxiety and Depression Scale) using adjusted linear regressions, with a mediation analysis of self-perceived mobility. We also tested whether the intervention increased step count in those with baseline clinical anxiety or depression.

Findings

We included 629 of 746 trial participants at baseline, of whom 376 contributed 12-month and 215 24-month data. At baseline, higher step counts were associated with fewer depressive symptoms (β = −0.11, 95% CI −0.17 to −0.05, p < 0.001) but, counter to our hypothesis, more anxiety symptoms (β = 0.12, 95% CI 0.06 to 0.19, p = 0.003). Over two years, change in step count was not associated with change in depressive or anxiety symptoms (all p ≥ 0.12). Self-perceived mobility problems mediated the association between step count and depressive but not anxiety symptoms. The intervention did not change step count in those with clinical anxiety or depression.

Conclusions

This provides the first evidence in older adults with cognitive concerns that higher step counts are associated with fewer depressive but more anxiety symptoms. This may reflect heterogeneity of a population that includes those with prodromal dementia and cognitive health anxiety. Step count did not predict symptoms over time.

Clinical implication

Step count may help distinguish anxiety and depressive symptoms in people presenting with cognitive concerns, or underlying reasons for cognitive concerns among those with functional cognitive disorders.

KEY MESSAGES

What is already known on this topic – summarise the state of scientific knowledge on this subject before you did your study and why this study needed to be done

Physical inactivity, depressive symptoms, and anxiety symptoms are linked to negative health outcomes and increased dementia risk. Existing research has shown that physical activity (e.g., walking) is associated with lower depressive and anxiety symptoms in healthy adults, and physical activity interventions are increasingly being employed to reduce these symptoms. Such interventions could offer benefit for individuals at risk of dementia; however, it remains unknown whether the relationship between physical activity and depressive and anxiety symptoms is the same in people with cognitive concerns, who may struggle to engage in planned physical activities.

What this study adds – summarise what we now know as a result of this study that we did not know before

This study extends existing research by showing that higher step counts were associated with fewer depressive symptoms in older adults at risk of developing dementia (i.e., with subjective cognitive decline [SCD] or mild cognitive impairment [MCI]). However, contrary to existing research, higher step counts were associated with more anxiety symptoms in this population. Self-perceived mobility problems fully mediated the association between step count and depressive symptoms, but did not mediate the association with anxiety symptoms, suggesting that the mechanisms linking step count with depressive and anxiety symptoms differ in older adults at risk of dementia. In longitudinal analyses, neither the intervention nor change in step count was associated with change in symptoms, indicating that step count may be a correlate of symptoms rather than a modifiable target in this population.

How this study might affect research, practice or policy – summarise the implications of this study

Walking interventions may be most appropriate for older adults with SCD or MCI experiencing depressive symptoms. Several studies have questioned whether among individuals with obsessional anxiety symptoms who have eating disorders, fitness trackers may reinforce worries. In people presenting with cognitive concerns without dementia, anxiety symptoms will have heterogenous aetiologies: worries about memory loss, as well as health anxieties that include fears of getting dementia. It is important to reflect on the impact of generic messaging on different groups, and perhaps to consider in further research the possibility that encouraging use of exercise trackers may compound these anxieties for a minority. For policymakers and practitioners, this underlines the importance of tailoring dementia prevention advice.