Brain fag is an example of a culture-bound syndrome. Once a common term for mental exhaustion, it is now encountered almost exclusively in West Africa. Seen predominantly in male students, it generally manifests as vague somatic symptoms, depression, and difficulty concentrating. It has similar symptoms to the Trinidadian illness studiation madness.
The term "brain fag" was used in the US as far back as 1852, describing an overworked brain, in 1877 to describe mental exhaustion in professionals similar to neurasthenia, and later in 1919 to describe mental fatigue in the elderly. The term 'fag' is believed to have been derived from 'fatigue'. This American usage declined by the 1950s. The modern African usage was first described in 1960, brain fag occurs most commonly in sub-Saharan Africa.
A Nigerian study in 2002 found that proficiency in English may be a risk factor. In South Africa, another large study found that socioeconomic status, female birth order, and depression were linked to the illness. A possible aetiology may be the "cultural clash" between African and Western societies. Brain fag is generally considered to be a depressive disorder, possibly linked with anxiety disorders.