I will never forget the immediate sense of well being I felt after taking B12 supplements. My homocysteine levels have been significantly reduced.
“The association between higher serum B12 levels and decreased dementia risk may provide prognostic information for clinicians as they counsel patients on the disease course of PD and raises further questions regarding the potential importance of vitamin B12 in these patients."
Vitamin B12 has been a game changer for me. Went into bad depression and anxiety about six months ago for no reason and found out my levels were low. I now inject myself every two weeks.
Vitamin D supplementation worsens Alzheimer's progression: Animal model and human cohort studies 2022Relationship between brain iron deposition and mitochondrial dysfunction in idiopathic Parkinson’s disease March 2022B12 May Slow Progression and Maintain Cognitive Function 
Link between DHA levels and PD by Dr. Fuhrman
Low dose Lithium to prevent dementia in Parkinson’s
