http://nnr.sagepub.com/content/30/1/3?etoc
- Giovanni Di Pino, MD, PhD1⇑
- Giovanni Pellegrino, MD1,2
- Fioravante Capone, MD1
- Giovanni Assenza, MD, PhD1
- Lucia Florio, MD1
- Emma Falato, MD1
- Fiorenza Lotti, PhD1
- Vincenzo Di Lazzaro, MD1
- Giovanni Di Pino, Institute of Neurology, Campus Bio-Medico University, Via Alvaro del Portillo 200, Rome 00128, Italy. Email: g.dipino@unicampus.it
Abstract
In search for individualized predictors of
stroke recovery, the Val66Met polymorphism of the brain-derived
neurotrophic factor
(BDNF) is attracting great interest, because it has
a negative impact on neurotrophin function. Since stroke recovery
relies
on brain plastic processes, on which BDNF is
permissive, the dominant thought is in favor of a worse recovery in Met
carriers.
Conversely, we suggest that Met carriers do not
differ in terms of absolute ability to recover from stroke, but they do
differ
on the way they recover. In particular, Met
carriers rely more on subcortical plasticity, while ValVal patients more
on intracortical
plastic processes. Indeed, the direct evidence of
impaired Met carrier recovery is inconsistent, as a high worldwide
diffusion
of the polymorphism suggests. The plasticity taking
place in cortex, which is the one targeted by noninvasive brain
stimulation
strategies aimed at enhancing recovery, is less
pronounced in Met carrier stroke patients, who have instead spared
global
recovery potential. Enhanced subcortical plasticity
sustains better stroke recovery of Met carrier mice: this may also
happen
in humans, explaining the weaker interhemispheric
cortical excitability imbalance recently described in Met carriers.
Thus,
BDNF haplotype determines mechanisms and structures
involved in stroke recovery. The less pronounced cortical plasticity of
Met carrier implies that plastic changes induced by
interventional neurophysiological protocols would be better predictors
of ValVal chronic outcome and those protocols would
be more effective to boost their recovery. Other strategies, more
focused
on subcortical mechanisms, should be used in Met
carriers.
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