Mental State & Activity

Executive Summary

• Mental health is a critical component of overall well-being, with depression, anxiety, and stress being the most prevalent concerns globally.
• The American College of Sports Medicine (ACSM) recommends a minimum of 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity exercise per week, with evidence suggesting that step counts exceeding 5,000 per day are associated with improved mental health.
• This study examines the relationship between daily step counts, measured via the Sahha app, and mental health levels assessed by the Depression, Anxiety, and Stress Scales-21 (DASS-21).
• Depression: Each additional 1,000 steps per day was associated with a statistically significant decrease of 0.5631 points on the depression scale (p = 0.006). Age also had a significant negative association with depression scores (p = 0.041), while gender was not a significant predictor.
• Anxiety: Each additional 1,000 steps per day was associated with a 0.2750-point reduction in anxiety scores (p = 0.030). Age was also a significant predictor (p = 0.001), whereas gender was not significant.
• Stress: A 1,000-step increase was linked to a 0.3201-point reduction in stress scores (p = 0.043). Unlike the depression and anxiety models, gender was significant, with female participants reporting higher stress levels than males (p < 0.001). Age was also negatively associated with stress scores (p = 0.010).

1. Introduction

Mental health is a key determinant of overall well-being and has gained prominence in recent years. In the general population, the most common mental health concerns relate to depression, anxiety, and stress. The term common mental disorders refers to depression and anxiety disorders due to their high prevalence in the population. A global meta-analysis found that 29.2% of individuals report experiencing a common mental disorder at some point in their lifetime.

However, it is important to distinguish between the emotional states of depression, anxiety, and stress and clinically diagnosed affective disorders. While many individuals experience fluctuations in these emotional states, most do not meet the diagnostic criteria for clinical affective disorders, as their symptoms are often mild, transient, and do not significantly impair daily functioning.

Common tools for screening depression, anxiety, and stress levels include the Patient Health Questionnaire-9 (PHQ-9), Generalized Anxiety Disorder-7 (GAD-7), Perceived Stress Scale-10 (PSS-10), and Depression Anxiety Stress Scales-21 (DASS-21). These instruments are widely utilized in both clinical and research settings to assess the presence and severity of depressive, anxiety, and stress-related symptoms.

Among the various factors influencing mental health, physical activity plays a crucial role in improving both physical and psychological outcomes. The American College of Sports Medicine (ACSM) recommends engaging in aerobic exercise 3–5 days per week, accumulating at least 150 minutes of moderate-intensity exercise or 75 minutes of vigorous-intensity exercise per week. Alternatively, individuals can aim for approximately 7,000–8,000 steps per day to achieve similar health benefits. Specific studies found that individuals with more than 5,000 steps per day have significantly lower depression scores.

This study aims to:

• Examine the correlation between step counts measured from the Sahha app and mental health levels as measured by DASS-21 (Depression, Anxiety, and Stress scores).
• Quantify the change in DASS-21 Depression, Anxiety, and Stress scores per 1,000 additional steps.

2. Methods

2.1 Data Sources and Participants

The study was conducted between February 2023 and June 2023. Participants were recruited from participant recruitment services. Inclusion criteria include:

1. Age from 18-65
2. Has a smartphone (at least Android version 8+ or iPhone 6) with internet connection
3. Proficient in English

During this period, a total of 6,482 DASS-21 responses were collected from 661 unique participants. Participants also provided step count data collected via smartphone sensors. The step count data for the 7 days preceding each DASS-21 response was mapped to the corresponding mental health assessment.

After filtering out responses with insufficient step count data, the final dataset comprised 1,835 DASS-21 responses from 301 unique participants. The dataset includes detailed demographic information such as age and sex for all participants.

2.2 Data Processing and Statistical Analysis

Step count data over the 7 days preceding a DASS-21 response was averaged to obtain an average daily step count associated with each DASS-21 response. To account for intra-individual correlation, we aggregated DASS-21 responses from the same user to obtain mean values of daily step counts and DASS-21 scores for each participant. The step count was divided by 1,000 to improve interpretability of the coefficients.

To examine the association between daily step count and anxiety, depression, and stress scores from the DASS-21, we performed multivariate linear regression with age and gender as covariates.

Model:

score = β0 + β1 * age + β2 * gender + β3 * daily_steps

Where:

• Score refers to depression_score, anxiety_score, or stress_score.
• daily_steps refers to the average number of steps per day in the 7 days before the participant responded to the DASS-21.
• Gender refers to the gender reported at study onboarding.

3. Results

3.1 Depression Score (Regression Results)

In the depression model, the coefficients for age (β = -0.0964; 95% CI: -0.189 to -0.004; p = 0.041) and steps (β = -0.5631; 95% CI: -0.962 to -0.164; p = 0.006) were statistically significant. The coefficient for gender was not statistically significant (β = -1.3827; 95% CI: -3.475 to 0.709; p = 0.194).

3.2 Anxiety Score (Regression Results)

In the anxiety model, the coefficients for age (β = -0.1024; 95% CI: -0.160 to -0.045; p = 0.001) and steps (β = -0.2750; 95% CI: -0.523 to -0.027; p = 0.030) were statistically significant. The coefficient for gender was not statistically significant (β = -0.9273; 95% CI: -2.230 to 0.375; p = 0.162).

3.3 Stress Score (Regression Results)

In the stress model, gender (β = -3.0504; 95% CI: -4.676 to -1.425; p < 0.001), age (β = -0.0947; 95% CI: -0.167 to -0.023; p = 0.010), and steps (β = -0.3201; 95% CI: -0.630 to -0.010; p = 0.043) were all statistically significant.

4. Discussion

Across the three models (depression, anxiety, and stress), the significance of the variables gender, age, and total steps shows distinct patterns.

Gender was not a statistically significant predictor in the depression model or the anxiety model. This suggests that there are no meaningful differences in depression or anxiety scores between genders in this sample. However, in the stress model, gender was highly significant (β = -3.0504; 95% CI: -4.676 to -1.425; p < 0.001). This suggests that female participants scored 3.05 points higher on the stress scale than male participants.

Age was a statistically significant predictor across all three models. Age also had a negative coefficient in all three models (-0.0964, -0.1024, and -0.0947 in the depression, anxiety, and stress models respectively). The negative coefficients indicate that older individuals tend to have lower scores for depression, anxiety, and stress.

Total steps was also a significant predictor in all three models and had a negative coefficient, reinforcing the relationship between physical activity and mental health. This suggests that within our sample, each additional 1,000 average steps per day is associated with a 0.5631, 0.2750, and 0.3201 point decrease in the depression, anxiety, and stress scales of the DASS-21 respectively.

5. Limitations

• DASS-21 relies on subjective responses, which may introduce reporting bias.
• There are known inaccuracies in smartphone-derived step counts which could under or overestimate the effect sizes of step count on the scores. However, our findings are highly consistent with existing literature; thus, we do not expect the findings to be significantly altered by higher measurement accuracy.

6. Conclusion

Understanding the relationship between step counts and depression can provide valuable insights into behavioral interventions for mental health. By showing the effects of increased step count on standardized measures of stress, anxiety, and depression, this study contributes to the growing body of evidence supporting physical activity as a modifiable factor in mental well-being.