Brain Fog in Hypothyroidism: Understanding the Patient's Perspective

Abstract

Objective: Patient-centered studies have shown that several patients on thyroid hormone replacement therapy for hypothyroidism exhibit persistent symptoms, including "brain fog." Here, we aimed to determine which of these specific symptoms are associated with brain fog, identify patient-reported factors that modify these symptoms, and identify patient concerns related to brain fog not included in thyroid-specific questionnaires.

Methods: A survey on brain fog symptoms adapted from thyroid-specific patient-reported outcome was distributed online. Textual data analysis was performed to identify common areas of concern from open-ended survey responses.

Results: A total of 5170 participants reporting brain fog while being treated for hypothyroidism were included in the analysis. Of these, 2409 (46.6%) participants reported symptom onset prior to the diagnosis of hypothyroidism, and 4096 (79.2%) participants experienced brain fog symptoms frequently. Of the symptoms listed, participants associated fatigue and forgetfulness most frequently with brain fog. More rest was the most common factor provided for improving symptoms. The textual data analysis identified areas of concern that are not often included in thyroid-specific quality of life questionnaires, including a focus on the diagnosis of hypothyroidism, the types and doses of medications, and the patient-doctor relationship.

Conclusion: Brain fog in patients treated for hypothyroidism was associated most frequently with fatigue and cognitive symptoms. Several additional areas of patient concern were found to be associated with brain fog, which are not typically addressed in thyroid-specific questionnaires.

Keywords: brain fog; fatigue; hypothyroidism; memory.

Fig. 1.

Flow diagram of survey participants.

Fig. 2.

The frequency of association between brain fog and each survey symptom. Participant responses to Likert-style questions associating 8 symptoms with brain fog. Participants rated each symptom based on how frequently they associated that symptom with brain fog. The results are presented as 3 groups: (1) all participants (blue), (2) those aged <50 years (orange), and (3) those aged ≥ 50 years (gray).

Fig. 3.

Flowchart of textual data analysis with associated words by subgroup. Textual data analysis identified 2 main groups and 5 subgroups among all classifiable textual units. Associated words are ordered from the highest to lowest strength of association. Strength of association was determined using the chi-square test. Plus symbols denote the reduced root word form. Freq = frequency; NDT = natural desiccated thyroid. *Endocrinol represents endocrinologist.