Brain fog

Brain fog is an informal term for a cluster of cognitive complaints, including difficulty concentrating, slowed thinking, forgetfulness and a sense of reduced mental clarity.

It is a symptom rather than a diagnosis, and people describe it in different ways: losing a train of thought mid-sentence, struggling to find words, re-reading the same paragraph or feeling mentally sluggish. Contributors are wide-ranging and include poor sleep, stress, depression, hormonal shifts during pregnancy or menopause, medication side effects, thyroid disorders, nutritional deficiencies, long COVID, chemotherapy and chronic inflammatory conditions.

Because so many causes overlap, evaluation starts with a careful history, review of sleep and medications, and basic laboratory tests, with formal cognitive testing reserved for persistent or worsening symptoms. Addressing the underlying contributor is the main approach. Brain fog appears in discussions of sleep problems and chronic inflammatory response syndrome, but there is no established cannabidiol indication for cognitive fog.