Homocysteine
Homocysteine is a non-proteinogenic α-amino acid. It is a homolog of the amino acid cysteine, differing by an additional methylene bridge. It is biosynthesized from methionine by the removal of its terminal Cε methyl group.
High serum homocysteine levels were independently associated with idiopathic normal pressure hydrocephalus in deep perforating arteriopathy (DPA). However, further research is needed to determine the predictive value of homocysteine and to confirm the underlying mechanism between homocysteine and iNPH 1)
There is minimal evidence for the use of TGF-β1, TBR-II, homocysteine, and interleukins (particularly IL-1β, IL-6, and IL-10). However, the available evidence suggests that these biomarkers warrant further investigation. Aβ42, tau, p-tau, NFL, and LRG have the greatest amount of evidence for their predictive value in determining shunt responsiveness in iNPH patients. Future research should be guided by, but not limited to, these biomarkers 2).
Increasing evidence indicates that an elevated total serum homocysteine level is directly and indirectly associated with Cerebral small vessel disease (cSVD), and endothelial dysfunction plays an active role in this association. Hyperhomocysteinemia affects endothelial function through oxidative stress, inflammatory pathways, and epigenetic alterations at an early stage, even before the onset of small vessel injuries and the disease. Therefore, hyperhomocysteinemia is potentially an important therapeutic target for cSVD. However, decreasing the homocysteine level is not sufficiently effective, possibly due to delayed treatment, which underlying reason remains unclear. In a review, Li et al. examined endothelial dysfunction to understand the close relationship between hyperhomocysteinemia and cSVD and identify the optimal timing for the therapy 3).
Serum homocysteine might have the potential to be a useful and cost-effective biomarker for predicting the occurrence of Delayed cerebral ischemia in Aneurysmal Subarachnoid Hemorrhage patients 4).
According to the results of a study, there was a significant correlation between the plasma Homocysteine (Hcy) levels and severity of trauma and prognosis in patients with Traumatic Brain Injury (TBI). 5).