The brain-derived neurotrophic factor (BDNF) gene is involved in mechanisms of synaptic
plasticity in the adult brain. It has been demonstrated that BDNF also plays a significant
role in shaping externally induced human brain plasticity. Plasticity induced in the
human motor cortex by intermittent theta-burst stimulation (iTBS) was impaired in
individuals expressing the Val66Met polymorphism.
To explore whether this polymorphism is also important for other neuroplasticity-inducing
tools in humans with modes of action differing from that of iTBS, namely, transcranial
direct current (tDCS) and random noise stimulation (tRNS), we retrospectively analyzed
the data of 64 subjects studied in our laboratory with regard to BDNF genotype.
Fifteen subjects with the Val66Met allele, 46 subjects with the Val66Val allele, and
3 Met66Met carriers were identified. The response of the Val66Met allele carriers
to stimulation differed in two protocols compared with the response of Val66Val individuals.
For iTBS (15 subjects, 5 heterozygotes), plasticity could be only induced in the Val66Val
allele carriers. However, for facilitatory tDCS (24 subjects, 10 heterozygotes), as
well as for inhibitory tDCS, (19 subjects, 8 heterozygotes), carriers of the Val66Met
allele displayed enhanced plasticity, whereas for transcranial random noise stimulation
(29 subjects, 8 heterozygotes), the difference between groups was not so pronounced.
BDNF polymorphism has a definite impact on plasticity in humans, which might differ
according to the mechanism of plasticity induction. This impact of BDNF on plasticity
should be taken into account for future studies, as well as having wider ranging implications
for the treatment of neuropsychiatric disorders with transcranial stimulation tools,
as it may predetermine their efficacy for the treatment of disease and rehabilitation.
Copyright © 2010 Elsevier Inc. All rights reserved.