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What is brain fog? An evaluation of the symptom in postural tachycardia syndrome



Adolescents with postural tachycardia syndrome (POTS) often experience ill-defined cognitive impairment referred to by patients as “brain fog.” The objective of this study was to evaluate the symptom of brain fog as a means of gaining further insight into its etiology and potential palliative interventions.


Eligible subjects who reported having been diagnosed with POTS were recruited from social media web sites. Subjects were asked to complete a 38-item questionnaire designed for this study, and the Wood mental fatigue inventory (WMFI).


Responses were received from 138 subjects with POTS (88 % female), ranging in age from 14 to 29 years; 132 subjects reported brain fog. WMFI scores correlated with brain fog frequency and severity (P < 0.001). The top ranked descriptors of brain fog were “forgetful,” “cloudy,” and “difficulty focusing, thinking and communicating.” The most frequently reported brain fog triggers were fatigue (91 %), lack of sleep (90 %), prolonged standing (87 %), dehydration (86 %), and feeling faint (85 %). Although aggravated by upright posture, brain fog was reported to persist after assuming a recumbent posture. The most frequently reported interventions for the treatment of brain fog were intravenous saline (77 %), stimulant medications (67 %), salt tablets (54 %), intra-muscular vitamin B-12 injections (48 %), and midodrine (45 %).


Descriptors for “brain fog” are most consistent with it being a cognitive complaint. Factors other than upright posture may play a role in the persistence of this symptom. Subjects reported a number of therapeutic interventions for brain fog not typically used in the treatment of POTS that may warrant further investigation.

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The authors would like to thank the research subjects for their participation and Dysautonomia International for their help with recruitment. The authors would also like to acknowledge Dr. Leonard Jason and Lindzi Shanks for their assistance designing the study questionnaire. This work was supported by the National Heart, Lung, and Blood Institute Grants RO1-HL074873 and RO1-HL087803 and by a grant from the CFIDS Association.

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On behalf of all authors, the corresponding author states that there is no conflict of interest.

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Correspondence to Julian M. Stewart.

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Ross, A.J., Medow, M.S., Rowe, P.C. et al. What is brain fog? An evaluation of the symptom in postural tachycardia syndrome. Clin Auton Res 23, 305–311 (2013).

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  • Postural tachycardia syndrome
  • Orthostatic intolerance
  • Cognition