Abstract
OBJECTIVES: Previous research on the biological markers of sustained post-concussion syndrome (PCS) after mild traumatic brain injury (mTBI) has suggested that those with mTBI have a reduction in prefrontal creatine (Dean et al., 2013), which is associated with poorer performance and reduced prefrontal BOLD response in cognitive tasks (Dean et al., 2015). In addition, dietary supplementation of creatine can alleviate PCS symptoms in the acute stage after injury (Sakellaris et al., 2006) or protect from PCS symptoms (Sullivan et al., 2000). It is an intriguing possibility that creatine may also alleviate symptoms, even in the long-term after injury. This study represents a first step, whereby it is investigated whether dietary supplementation leads to increases of creatine in the brain in a non-brain injured population, and whether this is related to behavioural performance or symptom report. METHODS: MRS and behavioural (n-Back; 0-, 2-, 4-back) data was acquired from ten vegetarian participants at three time points, one week apart. Week 1 was baseline, week 2 after placebo (maltodextrin) and week 3 after intervention (creatine monohydrate). Single voxel MRS was acquired from right dorsolateral prefrontal cortex. Both placebo and intervention were taken as 5g of powder dissolved in 250ml of water/milk, two times a day (morning/evening). RESULTS: Behavioural results indicated an effect of condition (0-, 2-, 4-back, p<0.001), session (week, p=0.013, and condition*session (p=0.006). Further analysis revealed this to be caused by a difference in the 4-Back between baseline and post-creatine (p=0.039), but not post-placebo (p=0.051). MRS analysis revealed no effect of session on total creatine (p=0.5 ), nor NAA (p=0.8), glutamate (p=0.3) or glutamine (p=0.2). CONCLUSIONS: According to this preliminary data, creatine supplementation does not systematically affect creatine levels in prefrontal grey matter. This is despite better cognitive performance post-creatine compared to baseline. Although, this could be caused by a learning effect as it was necessary to perform the dietary intervention in the same order to avoid washout effects. Control behavioural studies are being run to investigate the level of performance increase achieved by practise alone. The implications for previous research reporting a symptom alleviation, or cognitive enhancement in clinical and non-clinical populations may be that this alteration is due to non-neural mechanisms. However, this study only sampled one grey matter area, and future studies will be required to investigate a number of grey and white matter areas.