Common misconceptions about the BDNF pathway
BDNF is a neurotrophic factor in the muscle-brain axis. This page corrects common misconceptions about its signalling, sourcing evidence from narrative reviews of myokines and exercise-induced irisin-BDNF signalling.
What is BDNF?
Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor and myokine. It is a member of the neurotrophin family. BDNF is expressed in skeletal muscle and the central nervous system. In the context of the muscle-brain axis, BDNF is one of several myokines and exerkines, alongside irisin/FNDC5, interleukin-6 (IL-6), insulin-like growth factor-1 (IGF-1), cathepsin B, and growth differentiation factor-15 (GDF-15) [1].
The pathway centred on BDNF involves its receptor, tropomyosin receptor kinase B (TrkB), and downstream neuroplasticity signalling. This pathway is a focus of research into ageing, sarcopenia, and cognitive decline [1][2].
Research Studies
BDNF and the muscle-brain axis in ageing
A narrative review synthesised mechanistic and translational evidence on how skeletal muscle communicates with the ageing brain through myokines and exerkines, including BDNF [1]. The review reported that sarcopenia and cognitive decline frequently co-occur in older adults and that growing evidence indicates these conditions share a common biological substrate centred on the muscle-brain axis [1]. Progressive sarcopenia was described as disrupting this signalling, potentially accelerating cognitive impairment [1]. The findings were reported in older adults and in the context of ageing.
Irisin-BDNF signalling and exercise in ageing
A separate narrative review reported that age-related cognitive decline is closely associated with diminished neuroplasticity and disrupted neurotrophic signalling [2]. Exercise was described as a potent modulator of the irisin-BDNF axis, a molecular pathway with emerging relevance to healthy ageing, neuroprotection, and the prevention of neurodegenerative diseases in older adults [2]. These findings were reported in older adult populations.
BDNF as a myokine in sarcopenia and cognitive decline
In the muscle-brain axis review, BDNF was listed among myokines and exerkines that mediate muscle-brain communication [1]. The review indicated that progressive sarcopenia disrupts this signalling, which may contribute to cognitive impairment [1]. The evidence was synthesised from mechanistic and translational studies in older adults.
Comparison of myokines and exerkines in the muscle-brain axis
The following table lists myokines and exerkines identified in the muscle-brain axis review [1].
| Myokine/Exerkine | Role in muscle-brain axis |
|---|---|
| Irisin/FNDC5 | Mediator of muscle-brain communication |
| BDNF | Mediator of muscle-brain communication |
| IL-6 | Mediator of muscle-brain communication |
| IGF-1 | Mediator of muscle-brain communication |
| Cathepsin B | Mediator of muscle-brain communication |
| GDF-15 | Mediator of muscle-brain communication |
All entries are based on the narrative review by [1].
Exercise-induced irisin-BDNF signalling in neurodegeneration
The narrative review on exercise-induced irisin-BDNF signalling reported that this axis has emerging relevance to neuroprotection and the prevention of neurodegenerative diseases in older adults [2]. The findings were specific to older adult populations and were based on a narrative synthesis of existing literature.
BDNF and neuroplasticity in ageing
Diminished neuroplasticity and disrupted neurotrophic signalling were reported to be closely associated with age-related cognitive decline [2]. BDNF, as a neurotrophic factor, is part of this signalling framework. The evidence was reported in older adults [2].
BDNF in the context of sarcopenia
Sarcopenia was described as disrupting muscle-brain signalling, including BDNF-mediated communication, which may accelerate cognitive impairment [1]. This finding was reported in older adults with sarcopenia and cognitive decline [1].
BDNF and the irisin-BDNF axis in healthy ageing
The irisin-BDNF axis was reported to have relevance to healthy ageing, neuroprotection, and the prevention of neurodegenerative diseases [2]. Exercise was identified as a modulator of this axis [2]. The evidence was specific to older adult populations.
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Sources
- [1] Myokines as molecular mediators of the muscle-brain axis: Mechanisms linking sarcopenia to cognitive decline and implications for preventive strategies in ageing - A narrative review
- [2] Exercise-induced irisin-BDNF signaling in aging: implications for cognitive decline, sarcopenia, and neurodegeneration. A narrative review