# Brain fog symptoms in individuals with and without post COVID-19 condition: translation and validation of the brain fog scale

## TL;DR

This study translated and validated a brain fog scale for Greek speakers and found that people with post-COVID-19 condition report more brain fog symptoms.

## Contribution

The study validates the Brain Fog Scale in Greek and shows higher brain fog symptoms in post-COVID-19 condition individuals.

## Key findings

- The Brain Fog Scale retained its three-factor structure in Greek with high internal consistency.
- Individuals with post-COVID-19 condition reported significantly more brain fog symptoms.
- Impaired cognitive acuity was the most affected factor among post-COVID-19 condition individuals.

## Abstract

Brain fog describes a heterogenous symptom encompassing cognitive symptoms, mental fatigue and reduced mental clarity, particularly prevalent among individuals with Post COVID – 19 Condition (PCC). This study aimed to translate and validate the Brain Fog Scale (BFS), originally developed in Polish, among a Greek-speaking population and explore whether individuals diagnosed with PCC report significantly more brain fog symptoms, compared to those without PCC.

The BFS was translated in Greek, using a forward – backward translation process and was administered online. Principal Component Analysis and Confirmatory Factor Analysis were run to assess factor structure.

A total of 602 individuals (76.6% female) completed the BFS, of which 36 had a self-reported diagnosis of PCC. Internal consistency for the entire sample was excellent, α = 0.96. The BFS largely retained its original three factor structure with little variability: (1) impaired cognitive acuity (α = 0.95), (2) inattentiveness (α = 0.92), (3) mental exhaustion (α = 0.84). A Mann-Whitney U test revealed that individuals diagnosed with PCC reported significantly more brain fog symptoms compared to those without PCC, U = 2178.50, p = .011. MANOVA analyses further indicated significantly higher scores in the impaired cognition Factor among individuals with PCC, F(1, 125) = 7.32, p = .008.

The BFS comprises a valid tool for assessment of brain fog and can facilitate person-centred rehabilitation planning in PCC. Findings are discussed in relation to the literature regarding brain fog symptom burden in PCC with suggestions for future research made.