Micronutrient intervention effects on cognitive outcomes in post-acute traumatic brain injury

Traumatic brain injuries result in a complex pathophysiological cascade that includes neuroinflammation, cellular energy dysregulation and axonal injury (Werner & Engelhard, 2007). Nineteen essential vitamins and minerals, along with omega-3 polyunsaturated fatty acids, are required by the body for competent cellular function. These cannot be synthesized by the body and must therefore be ingested either as part of the diet or through supplementation. Previous research has highlighted a relationship between micronutrient (vitamins, minerals, omega-3) levels and cognition in a range of neurological conditions (Bitarafan et al., 2014; Moore et al., 2012; Veronese et al., 2016), however there is very little research in post-acute traumatic brain injury (TBI). The aims of this thesis were to investigate the effects of micronutrient supplementation on cognition in both a normative and a TBI population, while also gaining an insight into the levels of micronutrients present in the diets of these participants. In the TBI population the hypothesis was that by nutritionally supporting these individuals this would improve cellular functioning and neuronal repair following injury, reducing the effects of ongoing secondary cascade mechanisms, with improved cognitive function as the outcome. Study one (normative study) demonstrated significant improvements in cognition, specifically memory and executive functions, following a relatively short eight-week intervention period, particularly in those taking a broad-spectrum multimicronutrient. Study two (TBI population) used a cross-over study design (omega-3 and multimicronutrient) with parallel placebo group. The omega-3 intervention consistently resulted in improved learning, attention, processing speed and set shifting, whereas improvements following the multimicronutrient intervention were more limited. Analyses of food diaries from participants in both studies indicated that levels of fat-soluble vitamins, some B vitamins, and minerals are below recommended intake in diet. Results of these studies indicate that micronutrient interventions can result in cognitive improvement in a relatively short period of time. This evidence provides a solid foundation for future micronutrient research in TBI populations which have the potential to serve as an adjunct to traditional rehabilitation strategies.