Quantifying the effect of body mass index, age, and depression severity on 24-h activity patterns in persons with a lifetime history of affective disorders.
BACKGROUND
Patients with affective disorders of different ages have been found to present weight changes and different circadian activity patterns. This study assessed the effects of age, Body Mass Index (BMI) and depression severity on the activity-rest cycle in persons with affective disorders using a novel multifactorial 24-h analysis method.


METHODS
Two hundred and thirty-six participants aged between 14 and 85 years underwent 5 to 22 days of actigraphy monitoring (mean duration = 14 days). BMI was also recorded and symptom severity was assessed with the Hamilton Depression Rating Scale (HDRS). Participants were divided into two groups: healthy controls (n = 68) and participants with a lifetime diagnosis of affective disorders (n = 168). First, the multiple regression method was employed to formulate the circadian activity pattern in term of the factors age, BMI and HDRS. For each group, the functional linear analysis method was applied to assess the relative effects of the factors. Finally, Wald-tests were used to assess the contribution of each factor on the circadian activity pattern.


RESULTS
In the affective disorders group, higher BMI was associated with higher activity levels from 3 am until 5.30 am and with lower activity levels from 10 am until 10.30 pm. Older age was associated with less activity across the day, evening, and night - from 11 am until 5.30 am. Higher HDRS scores were associated with higher activity around 1:30 am. In healthy controls, the effects of BMI and age on activity patterns were less pronounced and affected a narrower portion of the 24-h period.


CONCLUSION
These findings suggest that older age and higher BMI are linked to lower daytime activity levels. Higher BMI and worse symptom severity were also associated with nocturnal activity patterns suggestive of sleep disturbances. The influence of age and BMI on 24-h activity profiles appear to be especially pronounced in people with affective disorders.
['Banihashemi|Nahid|N|', 'Robillard|Rébecca|R|', 'Yang|Jean|J|', 'Carpenter|Joanne S|JS|', 'Hermens|Daniel F|DF|', 'Naismith|Sharon L|SL|', 'Terpening|Zoe|Z|', 'White|Django|D|', 'Scott|Elizabeth M|EM|', 'Hickie|Ian B|IB|']
D056044:Actigraphy D000293:Adolescent D000328:Adult D000367:Age Factors D000368:Aged D000369:Aged, 80 and over D015992:Body Mass Index D016022:Case-Control Studies D002940:Circadian Rhythm D003863:Depression D005260:Female D006801:Humans D016014:Linear Models D008297:Male D008875:Middle Aged D019964:Mood Disorders D011569:Psychiatric Status Rating Scales D012044:Regression Analysis D012146:Rest D012890:Sleep D012893:Sleep Wake Disorders D055815:Young Adult
Body mass index Depression Affective disorders Circadian activity pattern Actigraphy Multiple regression method Functional linear model