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. The previous study (Dean et al., 2015) demonstrated altered fMRI indices, correlated to reduced creatine, despite no difference in behavioural performance between those with mTBI and controls. This study therefore investigates the underlying functional changes brought about by creatine supplementation during a working memory task using combined fMRI and EEG in a non-brain injured population. METHODS: fMRI and EEG data was acquired during an n-back (0-, 2-, 4-back) task 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). Both placebo and intervention were taken as 5g of powder dissolved in 250ml of water/milk, two times a day (morning/evening). Analysis of the EEG and fMRI data is ongoing, and will be completed by the conference date. 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). If creatine supplementation enhances cognition, we predict that there should be a greater difference between target and non-target P300 in the post-creatine compared to post-placebo and baseline, particularly in the 4-Back. Furthermore, as previous work has linked reduced creatine to reduced prefrontal BOLD response, we predict increased prefrontal activity post-creatine in the 4-Back task. CONCLUSIONS: Participants demonstrate better cognitive performance post-creatine compared to baseline. However, it was necessary to perform the dietary intervention in the same order to avoid washout effects. Therefore, a control behavioural study is being run to investigate performance increases achieved by practise alone. Even if no alteration in cognitive performance is observed, there may be adaptations in underlying functional processing such that less effort is required to achieve the same performance. As such, this study may help unravel the mechanisms by which creatine may be having its effect on sustained PCS after mTBI.