SCED Myokines and Cognition in SCI

Rationale: Individuals with spinal cord injury (SCI) suffer from accelerated cognitive aging. In able-bodied individuals, a vast amount of studies have shown that exercise interventions can improve cognitive function. Myokines (i.e. factors released into the blood stream from muscle cells) are considered one of the mediators of this beneficial effect. Neuromuscular electrical stimulation (NMES), used to replace or support muscle training in disabled individuals with poor exercise possibilities, was shown to elicit a large release of myokines (in some studies larger than following voluntary exercise). However, so far, the effects of NMES on cognitive function have never been studied before. In fact, only one study has previously investigated the effect of exercise on cognitive function in persons with SCI.

Objective: The primary aim is to assess to what extent a 12 week intervention with NMES to the quadriceps muscles of people with SCI can change their performance on a set of cognitive tests. Secondarily, the investigators will measure to what extent NMES to the quadriceps muscles of people with SCI induces changes in blood levels of the myokine brain-derived neurotrophic factor (BDNF), which is considered a potential mediator of the exercise-cognition effect, facilitating neuroplastic processes.

Study design: A single case experimental design (SCED) with sequential multiple baseline time series and a single-armed prospective study design, with a random duration of the baseline phase ranging from 3 to 6 weeks, an intervention phase of 12 weeks, and a 12 week period without measurements, followed by a follow-up phase of 3 weeks; in addition to a single-armed prospective study design.

Study population: Individuals (n = 15) aged 18 years and older with a chronic SCI (>1y post-injury) and with visible or palpable contraction of the quadriceps muscles upon NMES will be recruited at the rehabilitation centre of Adelante in Hoensbroek, the Netherlands.

Intervention: The study participants will receive 30min of NMES using surface electrodes on the quadriceps muscles three times per week for a total duration of 12 weeks.

Main study parameters/endpoints: The primary outcome is cognitive function changes which will be measured using a secured smartphone application (e.g. m-Path). Secondary outcome measures are changes in the blood myokine levels of BDNF and changes in cognitive outcome scores on an verbal cognitive test battery.