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Circadian phase variation in bipolar I disorder.
Hader A Mansour1, Joel Wood, Kodvali V Chowdari
1Department of Psychiatry and Human Genetics, University of Pittsburgh School of Medicine, Western Psychiatric Institute and Clinic, PA 15213, USA.
Chronobiology International
|August 4, 2005
Summary
Bipolar I disorder (BD1) patients exhibit distinct circadian rhythm patterns, differing from controls and schizophrenia patients. Younger BD1 patients with rapid mood swings tend to have later circadian phases, impacting their sleep-wake cycles.
Area of Science:
- Neuroscience
- Psychiatry
- Chronobiology
Background:
- Circadian rhythm abnormalities are characteristic of bipolar I disorder (BD1).
- Morningness-eveningness (M/E) reflects stable circadian phase traits.
- Understanding circadian variations in BD1 is crucial for treatment.
Purpose of the Study:
- To investigate circadian variations in M/E using the Composite Scale (CS) in BD1 patients.
- To compare M/E patterns between BD1 patients, healthy controls, and schizophrenia/schizoaffective disorder (SZ/SZA) patients.
- To explore factors influencing M/E heterogeneity within BD1.
Main Methods:
- Administered the Composite Scale (CS) to assess M/E in BD1 patients (n=75), controls (n=349), and SZ/SZA patients (n=81).
- Analyzed CS scores for correlations with age, gender, age at onset, and mood episode duration.
- Compared CS score distributions across diagnostic groups, controlling for age.
Main Results:
- CS scores correlated with age in controls but not gender.
- BD1 patients showed significantly different CS scores compared to controls and SZ/SZA patients when age was considered.
- BD1 CS scores exhibited a bimodal distribution, with younger patients and those experiencing rapid mood swings scoring lower (eveningness).
- CS scores positively correlated with age at onset and depressive episode duration in BD1, unlike in SZ/SZA groups.
Conclusions:
- Distinct M/E patterns exist in BD1 patients, differentiating them from other psychiatric groups.
- Age, rapid mood cycling, age at onset, and depressive episode duration are associated with circadian phase variations in BD1.
- Further research is needed to clarify the influence of medication, mood state, and illness chronicity on circadian patterns in BD1.