Brain-Derived Neurotrophic Factor (BDNF) as a Marker of Physical Exercise or Activity Effectiveness in Fatigue, Pain, Depression, and Sleep Disturbances: A Scoping Review.

Background/

Objectives

Brain-derived neurotrophic factor (BDNF) has been investigated as a potential mechanistic marker or therapeutic target to manage symptoms such as fatigue, pain, depression, and sleep disturbances. However, the variability in BDNF response to exercise or physical activity (exercise/PA) and its clinical relevance in symptom management remains unclear. This scoping review assesses existing studies exploring the relationships between exercise/PA, symptoms, and BDNF levels, specifically focusing on fatigue, pain, depression, and sleep disturbances in adults.

Methods

Relevant studies indexed in PubMed and CINAHL were identified. Using systematic review software, two reviewers independently screened and evaluated full texts, based on the following criteria: human studies reporting BDNF levels in adults, using exercise/PA interventions, assessing symptoms (pain, fatigue, depression, and/or sleep disturbance) as outcomes, and published in English.

Results

Of 950 records, 35 records met the inclusion criteria. While exercise/PA is broadly supported for managing symptoms, 74.3% (n = 26) of studies reported increased BDNF levels, and only 40% (n = 14) showed significant increases following exercise/PA. Only 14% (n = 5) of studies demonstrated a significant relationship between changes in BDNF and symptoms. No significant differences in BDNF levels and symptoms were observed between different types of exercise (e.g., aerobic vs. strength vs. flexibility/stretching) and PA.

Conclusions

The current literature provides insufficient evidence to confirm BDNF as a marker for exercise/PA effectiveness on symptoms. Further clinical investigations are needed to validate its potential as a therapeutic target.