Subjective brain fog: a four-dimensional characterization in 25,796 participants

Area of Science:

• Neuroscience
• Cognitive Science
• Public Health

Background:

• Brain fog is a subjective experience linked to decreased productivity and morbidity, gaining attention post-COVID-19.
• Systematic characterization of brain fog and its correlates is lacking.

Purpose of the Study:

• To systematically characterize self-reported brain fog.
• To identify demographic, symptomatic, comorbidity, and cognitive factors associated with brain fog.

Main Methods:

• Cross-sectional study of 25,796 adults using a digital application for remote data collection.
• Analysis of 29 predefined variables, including symptoms, comorbidities, and cognitive scores.
• XGBoost machine learning model used to identify predictive features of brain fog.

Main Results:

• 28.2% of participants reported brain fog, associated with older age and female sex.
• Key correlates included difficulty concentrating, irritability, difficulty following conversations, long-COVID-19, concussion history, and higher migraine disability.
• Cognitive scores were marginally lower in individuals with brain fog.

Conclusions:

• Brain fog is a significant impairment affecting concentration and daily activities, particularly in individuals with long-COVID-19, migraines, or concussion.
• This study provides the largest characterization of subjective brain fog to date.
• Further research is needed to explore the full spectrum of brain fog symptoms and differentiate them from associated conditions.