The brain fatigue syndrome: a cross-diagnostic phenomenon.

Fatigue arising from diseases or conditions that affect the brain is well recognized. This form of fatigue, brain fatigue, is not comparable to ordinary tiredness that resolves with rest; rather, it reflects a profound and often long-lasting exhaustion. Many individuals struggle in silence, lacking the energy to advocate for their needs. As a result, they may become socially isolated and unable to participate fully in everyday life, despite intact motivation and desire to engage. This fatigue has a substantial impact on work ability, social functioning, and daily activities, making it a serious clinical concern that requires greater attention, improved treatment strategies, and expanded research efforts. In this paper, we refer to this profound fatigue as brain fatigue, typically accompanied by cognitive, emotional, and sensory symptoms. Together, these symptoms may constitute a syndrome, the brain fatigue syndrome (BFS). The aim of this paper is to suggest that BFS, with its cognitive, emotional, and sensory features, appears in a similar way across a wide range of diagnostic groups, despite apparently intact performance on cognitive tests. We propose that BFS appears to represent a manifestation of generalized cerebral involvement, although individuals may concurrently exhibit disease-specific symptoms or deficits related to a brain injury. The symptoms associated with BFS typically persist for the duration of the underlying brain-affecting condition or until recovery occurs. However, in a subset of individuals, BFS may become persistent beyond the expected recovery period, necessitating targeted rehabilitation interventions. We present a theoretical framework for understanding BFS and provide examples of potential treatment strategies for persistent symptoms, as no definitive cure is currently available. In summary, BFS is suggested to reflect brain involvement but is not specific to any single diagnosis.