BDNF polymorphism and differential rTMS effects on motor recovery of stroke patients.
BACKGROUND
The brain-derived neurotrophic factor (BDNF) gene often shows a single nucleotide polymorphism that is thought to influence synaptic plasticity. It also affects the modulatory effects of repetitive transcranial magnetic stimulation (rTMS) on motor cortex excitability.


OBJECTIVE
This study investigated whether BDNF polymorphism influences the effect of rTMS on the motor recovery of patients with stroke.


METHODS
Forty-four patients (mean age 53.8 years) experiencing unilateral motor weakness after stroke were recruited. rTMS was applied over the primary motor cortex of the affected hemisphere at 10 Hz with 1000 pulses/day for 10 days. Each patient's motor functions were assessed using the Fugl-Meyer assessment (FMA) and the box and block test (BBT) before, immediately after and 2 months after the intervention. BDNF genotyping was performed via PCR assays of whole blood samples. The patients' data were grouped and analysed into Val/Val and Met allele groups according to the presence or absence of the BDNF polymorphism.


RESULTS
Nine patients (20.5%) were classified into the Val/Val group, and thirty-seven patients (79.5%) were classified into the Met allele group. The patients' baseline motor functions did not differ between the two groups. The FMA and BBT scores showed significant improvement immediately after and 2 months after rTMS in both groups. In addition, the time and groups were found to interact significantly, with the Val/Val group improving to a greater extent than the Met allele group in terms of their FMA and BBT scores.


CONCLUSIONS
The findings suggest that the BDNF gene polymorphism negatively influences the effect of rTMS on the motor recovery of upper extremities in stroke patients.
Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea.
Won Hyuk
WH
Chang
Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea.
Oh Young
OY
Bang
Department of Rehabilitation Medicine, Pusan National University College of Medicine, Pusan National University Yangsan Hospital, Pusan, Korea.
Yong-Il
YI
Shin
Samsung Advanced Institute for Health Science and Technology, Sungkyunkwan University School of Medicine, Seoul, Korea.
Ahee
A
Lee
Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Harvard Medical School and Beth Israel Deaconess Medical Center, 330 Brookline Avenue, Kirstein Building, Room KS158, Boston, MA 02215, USA.
Alvaro
A
Pascual-Leone
Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular and Stroke Institute, Samsung Medical Center, Sungkyunkwan University School of Medicine, Korea; Samsung Advanced Institute for Health Science and Technology, Sungkyunkwan University School of Medicine, Seoul, Korea. Electronic address: yunkim@skku.edu.
Yun-Hee
YH
Kim
D000483:Alleles; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D005260:Female; D005838:Genotype; D006225:Hand / Q000502:physiology; D006801:Humans; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D020127:Recovery of Function / Q000235:genetics* / Q000502:physiology*; D020521:Stroke / Q000235:genetics* / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation; D016896:Treatment Outcome
D019208:Brain-Derived Neurotrophic Factor
BDNF; Motor recovery; Single nucleotide polymorphism; Stroke; rTMS