JMIR Publications

ABSTRACT

Background:

Analysing actigraphy data using standard circadian parametric models and aggregated nonparametric indices may obscure temporal information that may be a hallmark of the circadian impairment in psychiatric disorders. Functional data analysis (FDA) may overcome such limitations by fully exploiting the richness of actigraphy data and revealing important relationships with mental health outcomes. To our knowledge, no studies have extensively used FDA to study the relationship between sociodemographic, health and lifestyle, sampling and psychiatric clinical characteristics and daily motor activity patterns assessed with actigraphy in a sample of individuals with and without depression/anxiety.

Objective:

We study the association of daily motor activity patterns assessed via actigraphy with (1) sociodemographic, health and lifestyle and, sampling factors; (2) psychiatric clinical characteristics (i.e., presence and severity of depression/anxiety disorders).

Methods:

14-day continuous actigraphy data of 359 participants with current (n=93), remitted (n=176) or no (n=90) DSM-IV based depression/anxiety diagnosis was obtained from the Netherlands Study of Depression and Anxiety. The associations of patterns of daily motor activity, quantified via functional Principal Component Analysis (fPCA), and sociodemographic, health and lifestyle and, sampling factors and psychiatric clinical characteristics, were assessed using Generalized Estimating Equation regressions. For exploratory purposes, Function-on-Scalar Regression (FoSR) was applied to quantify the time-varying association of sociodemographic, health and lifestyle, sampling and psychiatric clinical characteristics with daily motor activity.

Results:

Four features of daily activity patterns captured the overall daily activity level (fPCA1, 34.3% variability), earlier versus later morning activity (fPCA2, 16.5% variability), biphasic versus monophasic activity (fPCA3, 14.8% variability), earlier versus later biphasic activity (fPCA4, 11.8% variability). Low overall daily activity level was associated with several sociodemographic, lifestyle, sampling and psychopathology variables (P<0.05): older age, higher education level, higher BMI, higher number of chronic diseases, higher number of cigarettes per day, non-working/school days, winter season, having current depressive/anxiety disorders, higher depressive symptom severity. Earlier morning activity was associated with older age, having a partner, work/school days, autumn and spring (ref. winter) (P<0.05). Monophasic activity was associated with older age (P<0.01). Biphasic activity was associated with work/school days, summer (ref. winter) (P<0.01). Earlier biphasic activity was associated with older age, work/school days, spring and summer (ref. winter) (P<0.01). In FoSR analyses, age, working and season were the main determinants having a time-varying association with daily motor activity (P<0.05).

Conclusions:

Features of daily motor activity extracted with fPCA reflect commonly studied factors such as the intensity of daily activity and preference for morningness/eveningness. Presence and severity of depression/anxiety disorders were found to be mainly associated with overall lower activity pattern but not with time of activity. Age, working and season were most strongly associated with patterns and time of activity; future epidemiological studies on motor activity in depression/anxiety may take these into account.