Table A6.

Pharmacotherapy of neurodegenerative diseases: Parkinson’s disease, epilepsy.

Levodopa is degraded by methylation → significantly higher HCys levels than in untreated Parkinson’s patients → increased risk of stroke, coronary artery disease, dementia and peripheral neuropathy [181]. Anticonvulsants, especially valproate, influence the metabolism of folic acid (inhibition of cellular receptors), vitamin B6 (increased degradation) and reduce betaine uptake → lowering of plasma level of the two vitamins and increase in HCys [182]—see Figure 2 Particular risk: carrier of the TT variant of the C677T mutation of the MTHFR—see Table 1

Substitution with vitamin B6, B12, folate lowers HCys levels [183]. Significantly more femoral neck and vertebral fractures [184] and brain atrophy Rev [185]. Pregnancy: 10-fold increased risk of abortion, malformations in 6–11% of newborns, often cognitive deficits [186]. Improvement after supplementation with folic acid and B6 [184] or folic acid and B12 [186].

Brain tissue: no HCys transsulfuration and no re-methylation of HCys to methionine by betaine (cf. Section 2.1) high sensitivity to folic acid and vitamin B12 deficiency.