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

Abstract

Purpose: 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.

Methods: 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).

Results: 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 %).

Conclusions: 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.

Fig. 1

Correlation between Wood mental fatigue inventory (WMFI) scores and brain fog severity. WMFI is scored on a scale from 0 to 36 in 1-point increments with higher numbers representing greater mental fatigue. Brain fog severity is ranked from 0 to 100 in 10-point increments with higher numbers representing greater severity

Fig. 2

Reported brain fog triggers. Dark grey bars represent the percentage of subjects that reported the condition to trigger brain fog. Light grey bars signify the percentage of subjects that reported the condition to trigger brain fog while supine. White bars represent the percentage of subjects who claimed that lying down relieved brain fog that was triggered by each condition

Fig. 3

Effects of non-pharmacologic (a) and pharmacologic (b) interventions for POTS on brain fog. The length of the bars shows the percentage of subjects who reported that the intervention improved brain fog (light grey bars) or made brain fog worse (dark grey bars). The percentages are out of the number of subjects who had tried each intervention, which is indicated by the numbers next to the bars