Posted by Phillipa on June 9, 2011, at 19:34:30
Seems postural sway may be a symptom of bipolar disorder according to study NIMH. Phillipa
From Medscape Medical News > Psychiatry
Off Balance? Postural Problems May Point to Bipolar Disorder
Deborah BrauserAuthors and Disclosures
June 7, 2011 Problems with postural control may be a core feature of bipolar disorder (BD) and not just a random symptom, new research suggests.In a small comparison study of 32 patients, those with BD showed a "greater sway magnitude" compared to healthy controls, especially when asked to close their eyes.
"The findings suggest that individuals with [BD] have deficits in sensorimotor integration and a reduced range of timescales available, which are needed to help them to make greater postural corrections," lead author Amanda Bolbecker, PhD, research scientist in the Department of Psychological and Brain Sciences at Indiana University in Bloomington, told Medscape Medical News.
Dr. Amanda Bolbecker"In addition, changes in their visual system really had some profound effects on their ability to maintain their balance," she added.
The investigators note it is possible that motor abnormalities may appear before other symptoms, signalling an increased risk for BD. The findings also raise the question of whether therapies for improving motor symptoms could also help with mood disorders.
"For a number of psychological disorders, many different psychiatric treatments and therapies have been tried, with marginal effects over the long term. Our study suggests that brain areas traditionally believed to be responsible for motor behavior might represent therapeutic targets for BD," added Dr. Bolbecker.
This study was published online May 18 in PLoS ONE.
Motor Function and Mood
According to the investigators, structural, neurochemical, and functional abnormalities have been identified in the brains of individuals with BD, including in key brain structures implicated in postural control, such as the cerebellum, brainstem, and basal ganglia.
"The brain area that I've been most interested in for a while is the cerebellum, which is connected to a lot of areas important for mood and cognition. People have traditionally thought of it mostly as being involved with motor coordination, but it's also been implicated in a number of psychiatric disorders," said Dr. Bolbecker, adding that she also wants to assess other mood and motor brain areas.
She noted that "it is well known" that patients with attention-deficit/hyperactivity disorder often have some motor abnormalities and that schizophrenia has been known to include movement abnormalities that precede illness onset.
"This has been looked at a couple of times in BD, but nobody has really looked at postural sway. And we chose that because we wanted to use a task that was quite sensitive."
For the study, 16 patients with BD (45% women; mean age, 38.6 years) and 16 age-matched healthy controls (55% women; mean age, 38.4 years) were enrolled at Larue Carter Memorial Hospital in Indianapolis.
All participants stood barefoot on a force platform for 2 minutes while instructed to be as still as possible. During that time, they were evaluated under 4 conditions: eyes open while standing with feet placed shoulder-width apart (open base), eyes closedopen base, eyes open with feet together (closed base), and eyes closedclosed base.
The investigators measured postural sway (the degree of adjustments made while standing by the participants), as well as center of pressure motion along the anterior-posterior and medio-lateral axes.
"Visual cues stabilize posture on longer time-scales, whereas proprioceptive [stance difference] cues are responsible for short timescale corrections. Therefore, if deficits in postural control exist in BD, manipulation of sensory input may be revealing with respect to specific domains in which sensory integration is affected," write the study authors.
Greater Sway
Results showed that patients with BD showed a significantly greater sway area, indicating reduced postural control, compared to the healthy controls (P < .01) and "decreased complexity in the medio-lateral direction," report the investigators.
Patients with BD also had a greater sway area than did the controls when their eyes were closed (P < .05), suggesting that "BD participants were impaired in their ability to make corrections to their sway pattern when no visual information was available."
No significant differences were found between open-base or closed-base stances, and none of the results were affected by mood or disorder severity.
"Overall, the evidence presented here is consistent with earlier findings of motor abnormalities in BD and is consistent with the proposed deficits in the cerebello-striatal-prefrontal circuit," write the researchers.
"Although the literature in this area is limited, a picture is emerging in which mood and motor dysfunction are comorbid pathophysiological features with closely overlapping core components."
Dr. Bolbecker reported that this was "a first pass study" and would next like to see research done that looks at these measures in a medication-naive population or in groups that is at risk for the disorder. "That will tell us a lot about whether motor symptoms are truly risk factors for onset of this illness."
She added that the investigators would also like to examine these risks in family members of patients with BD and to assess other tasks that are related to movement.
The study was funded by a grant from the National Institute of Mental Health and a 2007 National Alliance for Research on Schizophrenia and Depression Young Investigator Grant to Dr. Bolbecker. The study authors have disclosed no relevant financial relationships.
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