Actigraphy, a technique used to monitor sleep patterns, may prove useful in monitoring lithium response in patients with bipolar disorder (BD). Lithium is the recommended treatment for BD-I (mania with/without major depressive disorder) but guidelines vary regarding its use for BD-II (history of hypomania and major depressive disorder).
A group of researchers out of the United Kingdom and France conducted a study to find out if patients who responded positively to lithium had different sleep-wake profiles than those who responded negatively to the medication. They published their findings in the Journal of Affective Disorders.
Outpatients with BD who were affiliated with University of Paris psychiatric clinics participated in the study. Patients included were over age 18, were receiving psychiatric treatment for BD, were prescribed lithium, and were euthymic for at least 3 months before recruitment.
An independent investigator measured patients’ lithium responses using the Alda scale. Participants wore an actiwatch continuously on their non-dominant hand for 21 days and nights. Actigraph data were downloaded and measured.
Principal components analysis (PCA) showed a “lithium response dimension” accounting for more than 20% of the explained variance and characterized by 5 markers of circadian timing and rhythm. The analysis showed a weaker association between lithium response and sleep variables in BD-II patients compared to BD-I. PCA correctly classified 64% of all BD patients as lithium responders or non-responders.
Limitation of this study include the fact that measurement took place after the patients started taking lithium. The overall classification rate was “sub-optimal.” Also, the sample size of BD-2 patients was insufficient.
The researchers concluded, “the findings may encourage further research into a broad range of potential biomarkers of Li response, such as being undertaken by H2020-funded R-LiNK (Response to Li Network) and specific projects that explore whether rest-activity patterns might be combined with other potential markers of Li response to improve the specificity of predictions of likely benefit from this treatment.”
Etain B, Meyrel M, Hennion V, Bellivier F, Scott J. Can actigraphy be used to define lithium response dimensions in bipolar disorders? J Affect Disord. 2021 Feb 2;283:402-409. doi:10.1016/j.jad.2021.01.060