Defining brain fog across medical conditions

Area of Science:

• Neurology
• Cognitive Science
• Psychiatry

Background:

• 'Brain fog' is frequently reported across diverse chronic diseases, indicating a potential transdiagnostic phenomenon.
• Existing definitions of brain fog are variable, encompassing cognitive, affective, and fatigue-related symptoms.
• The precise nature and underlying mechanisms of brain fog remain unclear, necessitating further investigation.

Purpose of the Study:

• To characterize brain fog by reviewing research across multiple chronic conditions.
• To evaluate the definitions and objective correlates of brain fog.
• To explore the potential for brain fog as a transdiagnostic entity.

Main Methods:

• Systematic review of existing literature on brain fog in chronic diseases.
• Analysis of studies characterizing brain fog symptoms and their definitions.
• Examination of objective cognitive deficits associated with brain fog.

Main Results:

• Brain fog presents as a variable set of overlapping symptoms affecting cognition, fatigue, and affect.
• Evidence suggests brain fog may be a transdiagnostic entity with shared phenomenology and cognitive deficits.
• Linguistic ambiguity, shared cognitive impairments, and noncognitive factors are proposed as more likely explanations than shared neurobiology.

Conclusions:

• Brain fog is a complex phenomenon with overlapping symptoms across various chronic conditions.
• While potentially transdiagnostic, shared neurobiology is less likely than other contributing factors.
• Future research should focus on disambiguating the multifaceted nature of brain fog using standardized tools.