EASY-TO-UNDERSTAND SUMMARY:
GAIT AND BALANCE IN PTSD
How do balance and physical coordination differ in people with PTSD?
Over the years working with clients with PTSD and study participants, we became intrigued by the fact that a number of people referred to themselves as clumsy or uncoordinated. We asked ourselves, why would this be a common experience in this population?
We know that a sense of balance and coordination requires continuous input from our bodies to help guide our responses to our physical surroundings. And we know that this input comes from both external information (e.g., gathered through vision, touch), and internal body signals (e.g., from the inner ear, joints, and muscles). For example, through touch, our body might help us determine if our feet are in contact with the ground and if the ground is level, and through information sent from our joints, we might be able to tell if we’re standing on a hill, or if we’re in a seated position.
Unfortunately, such input can be disrupted by a number of things, including chronic stress (such as the stress that might lead to PTSD). These disruptions often involve changes in the signals coming from the body (e.g., inner ear/balance problems), as well as changes in one’s self-awareness of the body (e.g., feeling disconnected from our hands or feet). We conducted studies to begin an investigation into gait (i.e., how a person walks) and balance, and how they might be impacted by both the dissociative and non-dissociative subtypes of PTSD.
Do brain scans show differences in areas related to balance and movement in people with classic PTSD versus people with the dissociative subtype of PTSD?
Harricharan S, Nicholson AA, Densmore M, Théberge J, McKinnon MC, Neufeld RWJ, & Lanius RA. (2017). Sensory overload and imbalance: Resting-state vestibular connectivity in PTSD and its dissociative subtype. Neuropsychologia, 106, 169–178. http://dx.doi.org/10.1016/j.neuropsychologia.2017.09.010
In a quest to better understand the difficulties our participants often report in terms of balance and coordination, we wanted to begin investigating any vestibular system differences between people with the dissociative versus the non-dissociative subtypes of PTSD. The vestibular system is a complex network of brain structures and senses that helps us know where we are in space, maintain balance, and move through the environment. Research shows that PTSD often involves changes to some of these same brain structures and functions, for example, those involved in sensations and body-awareness. Knowing these structures are also part of the vestibular system, it makes sense that some of these changes could have an impact on balance and coordination too.
To begin investigating this, we designed a “resting state” fMRI (functional magnetic resonance imaging) brain scan study, comparing three groups of participants - those with the dissociative subtype of PTSD, those with the non-dissociative subtype, and those with no history of mental health diagnoses (i.e., our “control” group). “Resting state” brain scans involve participants lying in an fMRI scanner while letting their minds wander naturally, not focusing on anything in particular, as the scanner takes images of how the brain is working.
As predicted, we found differences in brain connections when comparing our three groups of participants, and found that these differences corresponded to the severity and type of PTSD symptoms. For example, those with the dissociative subtype of PTSD showed fewer connections to areas of the brain important for vestibular function. This difference might contribute to experiencing vestibular problems like poor balance, problems interpreting sensory information coming from multiple sources (e.g., coordinating information from vision, touch, and sound), and difficulty feeling separate from the environment.
Differences seen in the non-dissociative PTSD group suggest they tend to have less body awareness and less awareness of the environment, which may help explain this group’s tendency for hypervigilance. Since awareness of the environment doesn’t come as easily for them, they feel the need to be on the lookout for danger.
Overall, this study helps us understand the link between changes in sensory experiences typical of PTSD, awareness of one’s body and environment, and how altered awareness might contribute to changes in brain activity. Further research into this area will be necessary to better understand PTSD, and to find the most effective treatments.
