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Targeting motor activity may ease depressed mood in bipolar disorder

Interventions that focus on motor activity and energy may have greater efficacy than current approaches that target depressed mood in bipolar disorder, according to a study published in JAMA Psychiatry.

Using data from wrist-worn mobile monitoring devices, researchers found bidirectional associations between motor activity and sleep duration as well as unidirectional associations between motor activity and mood level.

“Consistent evidence now exists for the dysregulation of motor activity in people with bipolar disorder,” Kathleen Ries Merikangas, PhD, from the genetic epidemiology research branch at NIMH, and colleagues wrote. “However, most clinical research in mental disorders that uses mobile devices has focused on either sleep or motor activity rather than on the associations between them.”

Researchers conducted a nested case-control study to examine the directional associations among motor activity, energy, mood and sleep using mobile monitoring in a community-identified sample of adults and youth. They also examined whether these within-day associations differed between people with a history of bipolar disorder or major depression disorder and controls.

Participants wore actigraphy monitors — which collected minute-to-minute data on sleep duration and motor activity — for 2 weeks and completed ecological momentary assessments using a personal digital assistant — which measured mood and energy levels — four times each day for 2 weeks.

Of 242 participants, 54 had bipolar disorder (25 with bipolar I; 29 with bipolar II), 91 had MDD and 97 had no history of mood disorders. Merikangas and colleagues observed a unidirectional association between motor activity and subjective mood level (beta = –0.018; P = .04) as well as bidirectional associations between motor activity (beta = 0.176; P = .03) and subjective energy level (beta = 0.027; P = .03) and between motor activity (beta = –0.027; P = .04) and sleep duration (beta = –0.154; P = .04).

“Findings regarding the central role of motor activity patterns in mood regulation and the salience of subjective energy as a primary factor in motor activity suggest that motor activity may be a more malleable behavioral target of intervention than mood,” the researchers wrote.

Merikangas and colleagues explained that the unidirectional associations of motor activity with depressed mood suggest that rather than targeting mood elevation or stabilization in bipolar disorder and MDD, novel pharmacologic, physical and behavioral therapeutic approaches that target boosting energy and activity may be more effective.

“In addition, consideration of intrinsic rhythms in the timing of interventions, such as pharmacologic (eg, melatonin-based interventions) and/or behavioral interventions designed to enhance circadian rhythmicity may be more effective than interventions in one of these domains alone,” they wrote. – by Savannah Demko

Disclosure: Merikangas reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.