Key result
POTS is linked to ~6 percentage points greater cerebral blood flow velocity drop after cognitive stress.
Why the study?
The physiology underlying brain fog in the absence of orthostatic stress in postural tachycardia syndrome remains poorly understood.
Does prolonged cognitive stress induce greater reductions in cerebral blood flow velocity and cognitive performance in patients with postural tachycardia syndrome compared to healthy controls?
Case-Control (n=40)
No
Does prolonged cognitive stress induce greater reductions in cerebral blood flow velocity and cognitive performance in patients with postural tachycardia syndrome compared to healthy controls?
This study demonstrates that prolonged cognitive stress induces significant reductions in cerebral blood flow velocity and cognitive performance in POTS patients, providing a physiological basis for 'brain fog' independent of orthostatic stress.
May exacerbate seated cognitive symptoms in POTS; hypothesis-generating for CBFv-targeted interventions.
Background The physiology underlying "brain fog" in the absence of orthostatic stress in postural tachycardia syndrome (POTS) remains poorly understood. Methods and Results We evaluated cognitive and hemodynamic responses (cardiovascular and cerebral: heart rate, blood pressure, end‐tidal carbon dioxide, and cerebral blood flow velocity (CBFv) in the middle cerebral artery at baseline, after initial cognitive testing, and after (30‐minutes duration) prolonged cognitive stress test (PCST) whilst seated; as well as after 5‐minute standing in consecutively enrolled participants with POTS (n=22) and healthy controls (n=18). Symptom severity was quantified with orthostatic hypotensive questionnaire at baseline and end of study. Subjects in POTS and control groups were frequency age‐ and sex‐matched (29±11 versus 28±13 years; 86 versus 72% women, respectively; both P ≥0.4). The CBFv decreased in both groups (condition, P =0.04) following PCST, but a greater reduction in CBFv was observed in the POTS versus control group (−7.8% versus −1.8%; interaction, P =0.038). Notably, the reduced CBFv following PCST in the POTS group was similar to that seen during orthostatic stress (60.0±14.9 versus 60.4±14.8 cm/s). Further, PCST resulted in greater slowing in psychomotor speed (6.1% versus 1.4%, interaction, P =0.027) and a greater increase in symptom scores at study completion (interaction, P <0.001) in the patients with POTS, including increased difficulty with concentration. All other physiologic responses (blood pressure and end‐tidal carbon dioxide) did not differ between groups after PCST (all P >0.05). Conclusions Reduced CBFv and cognitive dysfunction were evident in patients with POTS following prolonged cognitive stress even in the absence of orthostatic stress.
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Wells et al. (2020) conducted a case-control in Postural tachycardia syndrome (POTS) (n=40). Postural tachycardia syndrome (POTS) vs. Healthy controls was evaluated on Change in cerebral blood flow velocity (CBFv) following prolonged cognitive stress test (p=0.038). Patients with postural tachycardia syndrome exhibited a greater reduction in cerebral blood flow velocity (-7.8% vs -1.8%, interaction p=0.038) and psychomotor speed following prolonged cognitive stress compared to healthy controls.
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