Physiopathology of Lower Cortical Activation in COPD Patients: Contribution of Cortical Neuromodulation
Condition: Physiology
Study type: Interventional

Summary: 
      Patients with COPD have lower cortical activation and higher cortical inhibitory levels. The
      purpose of this study is to test the reversibility the lower cortical activation by
      counterbalancing the increased cortical inhibitory levels with neuro-modulation.
    

Detailed description: 
      Chronic obstructive pulmonary disease (COPD) patients exhibit not only respiratory symptoms
      but also a peripheral muscular weakness. This weakness is characterized by a loss in
      strength, harmful for the patients' life quality and vital prognostic. Even if many papers
      have enlightened damages at a peripheral level, the muscular atrophy itself cannot totally
      explain the loss in force. Furthermore, the contractile properties of COPD muscles fibres are
      preserved. Consequently, it seems that the peripheral muscle weakness cannot only be
      explained by peripheral factors and central structures may be involved.

      A recent work showed that during quadriceps voluntary contraction, cortical activation in
      COPD patients was significantly lower than in healthy subjects, contributing in the loss in
      strength. However, the pathophysiology underlying this loss of strength is still unclear and
      two hypotheses can be advanced: 1) the influence of anatomical lesions in the brain of COPD
      patients and 2) the particular metabolism of this population. Indeed, COPD patients show a
      reduced oxidative activity and an increased glycolytic contribution (decreased type I fibres
      and increased type II fibres, increased glycolytic enzymes activity, increased metabolites
      production). This specific metabolic may lead to an over-activation of type III-IV afferents,
      projecting onto somatosensory cortex sensitive to metabolites at a peripheral level, and
      produce inhibitory activity on the primary motor cortex, seat of the motor control. What is
      reported in the literature so far, is that COPD patients display increased cortical
      inhibitory values than healthy subjects.

      Therefore, beyond understanding better the nervous mechanisms involved in the COPD's
      peripheral muscle weakness, the aim of this study is to counterbalance this increased
      cortical inhibitory level.

      We hypothesize that modulating inhibitory processes at a cortical level would induced a
      reduction of inhibitions in patients with COPD and an increase in the force produced. In case
      this hypothesis would be verified, we will be able to confirm that this increased cortical
      level in COPD patients is reversible and may be a target for rehabilitation.
    

Intervention name(s): Anodal transcranial direct-current-stimulation; Sham transcranial direct-current-stimulation
Intervention type(s): Device; Device
Intervention description(s): 2mA / 20min Anodal and Sham tDCS over dominant M1. Anodal tDCS consists of 30s of ramp up followed by 20min of stimulation and 30s of ramp down.; Sham tDCS consists of only 30s of ramp up followed by 30s of ramp down and no further stimulation.
Participants therefore have the same feeling for both modalities : slight itching due to the induced current at the beginning of the protocol (during around 30s) allowing no differentiation by the participant between the anodal or sham sessions.
Allocation: Randomized
Intervention model: Crossover Assignment
Masking: Triple (Participant, Care Provider, Investigator)
Primary purpose: Basic Science
Keywords: COPD; Transcranial direct-current stimulation; Transcranial magnetic stimulation; Motor-evoked potentials; Inhibition; Muscle weakness