Brain Fog & hEDS/HSD
Brain Fog and Cognitive Symptoms in Hypermobility
None of us writing this are doctors. This page collects what the published research actually says about brain fog and cognitive symptoms in hEDS/HSD, so you have something concrete to bring to a doctor.
Trouble concentrating, losing your train of thought, or feeling mentally slow when you are not physically unwell is a common complaint that is easy to write off as stress or tiredness. Research suggests, at least in some people, it may be tied to something more specific: how well your body regulates blood flow when you stand.
How Common Is Brain Fog in hEDS/HSD, and What's Driving It?
A 2025 cross-sectional study of 385 people clinically diagnosed with hEDS or joint hypermobility spectrum disorder used two validated tools - the Composite Autonomic Symptom Score (COMPASS-31) for orthostatic intolerance and the Cognitive Failure Questionnaire (CFQ) for cognitive complaints. It found orthostatic symptoms in 65% of participants and cognitive changes reported by 73%. More specifically, 36% said they experienced brain fog often.
The key finding was the relationship between the two: orthostatic intolerance scores and cognitive complaint scores were moderately and significantly correlated (r = 0.449, p = 0.03). That is not a huge correlation, so orthostatic intolerance clearly is not the whole story behind brain fog in this population, but it is a real, measurable link, not just two symptoms that happen to occur in the same people by chance.
What to do with this
If brain fog is a significant part of your experience, it is worth mentioning alongside any dizziness, lightheadedness, or other standing-related symptoms rather than as a separate, unrelated complaint - this research suggests they may share a common driver in at least some people. The POTS and orthostatic intolerance research covered elsewhere on this site is a reasonable starting point for that conversation with a doctor, since improving orthostatic symptoms may have some effect on cognitive symptoms too, though this study did not test that directly.
Sources referenced on this page