Metabolite changes and impact factors in mild traumatic brain injury patients: A review on magnetic resonance spectroscopy

The high incidence of mild traumatic brain injury (mTBI) and the associated post-concussion symptoms, such as headache and cognitive deficits, have captured the significant attention from researchers globally. Magnetic resonance spectroscopy (MRS), a non-invasively technique derived from Magnetic Resonance Imaging (MRI), provides a complement approach to investigating brain metabolites as biomarkers for in vivo pathophysiological changes following mTBI, which are not evident in traditional MRI or CT scans. However, the separate review of MRS in mTBI patients has been limited, given the myriad factors involved and wide spectrum of TBI severity. In this review, we first delve into metabolite changes after mTBI, highlighting a reduction in N-acetyl-aspartate (NAA) as a relatively stable marker associated with neuronal loss or disfunction following mTBI. We then discuss the varying results observed for different metabolites and enumerate possible factors contributing to these inconsistent findings. These factors include variations in experimental methods, such as scanner types, acquisition methods, and region of interest. Additionally, we address subjects-specific factors, such as occupation, cause of injury, control group selection, injury stage, severity, the number of traumatic events, and the assessment of clinical features. Finally, we discuss the trend for future research in this field.