In a recent study published in JAMA Neurology, researchers assessed the association between the number and intensity of steps taken per day and dementia incidence among adults residing in the United Kingdom (UK).
Step count is a popular approach to providing physical activity (PA) targets for the general public. Higher step counts may reduce the risk of cancer, cardiovascular mortality, and incident diabetes, especially if performed with increased intensity. In addition, step count-based recommendations are easy to communicate, interpret, measure, and memorize and may be ideal for formulating guidelines to prevent dementia. However, the relationship between the number and cadence of daily steps with the incidence of dementia is unknown.
Study: Association of Daily Step Count and Intensity With Incident Dementia in 78,430 Adults Living in the UK. Image Credit: alexei_tm / Shutterstock
About the study
In the present study, researchers investigated the optimum count and cadence of steps required to prevent dementia among UK adults.
Data were obtained from the UK Biobank (UKBB) prospective cohort study conducted between February 2013 and December 2015, in which follow-up assessments were performed over seven years. Participants were asked to wear an accelerometer on their dominant wrist throughout the day on all days of the week to measure their PA.
Adult individuals who wore wrist accelerometers and provided accelerometer data of >3 weekdays and one weekend were included in the analysis. Dementia ascertainment was based on multiple registry data and was performed through October 2021. The study exposure was accelerometer-monitored step count per day, comprising incidental and purposeful steps of <40 and >40 steps/minute, respectively.
In addition, peak half-hour intensity [i.e., average steps/minute accelerometer-reported for the highest 30 (but may not be consecutive) minutes per day]. The prime study outcome and measures were incident fatal or non-fatal dementia, obtained via linkage with primary care or inpatient hospital admission records or reported as the contributory or underlying death cause in mortality registers.
Data adjustments were made for sex, age, ethnicity, race, socioeconomic status, education, alcohol consumption, smoking, vegetable and fruit intake, cancer and cardiovascular disease family history, medications, valid accelerometer wearing days, and accelerometer-monitored sleep. Spline Cox regression modeling was used for the analysis, and the hazard ratios (HR) were calculated.
Further, sensitivity analyses were performed to minimize reverse causation chances, wherein participants diagnosed with dementia within the first two follow-up years were removed, and data were adjusted for glycated hemoglobin (HbA1c), cholesterol, mean arterial pressure, and body mass index (BMI).
Results
In total, 103,684 adults were identified with available wrist accelerometer data, of which 23,638 were excluded due to: (i) invalid accelerometer data (n=12,068), (ii) had prevalent cancer, dementia or cardiovascular health issues (n=9,636), (iii) with <3 weekdays and one weekend of valid accelerometer data (n=1,934). As a result, 78,430 adult individuals with complete covariate data were included in the final analysis.
The average age of the included cohort was 61 years, of which the majority (55%, n=43, 390 were women and the remaining 45% (n=35,040) were men. Among the participants, 97%, 0.8%, 0.8%, 0.5%, and 1.1% were Whites, Blacks, of unspecified ethnicity, of mixed ethnicity, and Asians, respectively. Higher step counts were observed for younger and healthier (lower alcohol consumption and higher vegetable and fruit intake) females.
Over seven years, 866 participants were diagnosed with dementia (average age, 68 years; 480 men and 386 women; 98%,0.7%, 0.6%, 0.4%, and 0.7% Whites, Blacks, Asians, mixed ethnicity, and of unspecified ethnicity, respectively). Nonlinear associations were found between step count and daily intensity, and dementia incidence.
The optimal number of steps (dose) (i.e., the value of exposure at which maximal reduction in dementia risk was found) and minimal dose (i.e., the value of exposure at which dementia risk was 50% lower than the maximal risk reduction value) were 9,826 steps and 3,826 steps, respectively, with corresponding HR values of 0.5 and 0.8.
The optimal incidental and purposeful intensity doses were 3,677 steps and 6,315 steps, respectively, with corresponding HR values of 0.6 and 0.4. The optimal dose for peak half-hour intensity was 112 steps taken per minute with an HR value of 0.4. The results remained unaltered after the sensitivity analyses.
Overall, the study findings showed that higher step counts were related to lower dementia incidence risks. Taking 9,800 steps daily with higher intensity would be optimal for reducing dementia risks. The authors believe that the present study is the first of its kind and that understanding the daily step count and dementia incidence association is essential to determine the optimal stepping dose and intensity for the prevention of dementia.
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