Alzheimer's disease and total plasma aminothiols.
BACKGROUND
Plasma homocysteine is elevated in Alzheimer's disease, but little is known regarding levels of related aminothiols in the disease. We therefore determined total plasma homocysteine, cysteine, and glutathione levels in patients and control subjects and investigated their relationship with cognitive scores.


METHODS
We performed a prospective, case-controlled survey based in two UK Psychogeriatric Assessment Centres. Fifty patients with features compatible with DSM-IV criteria for primary degenerative dementia of Alzheimer type were recruited together with 57 cognitively intact age- and gender-matched control subjects. Mini-Mental State and Alzheimer's Disease Assessment Scale-Cognitive Subsection (ADAS-Cog) scores were determined for patients and control subjects. Aminothiols were assayed with an automated high-performance liquid chromatography (HPLC) system.


RESULTS
Patients had significantly elevated total plasma homocysteine (p <.001) and cysteine (p <.01), but there were no group differences for total plasma glutathione. Glutathione was, however, a highly significant and independent predictor of cognitive scores in patients (p =.002); lower plasma levels were associated with more severe cognitive impairment.


CONCLUSIONS
Total plasma homocysteine and cysteine are elevated in Alzheimer's disease, suggesting intact transsulphuration but defective remethylation of homocysteine in the disease. Total plasma glutathione levels in patients correlate with cognitive scores. Taken together, these observations perhaps reflect the differential effects of Alzheimer's disease-related oxidative stress on the two key pathways of homocysteine metabolism.
McCaddon
Andrew
A
University of Wales College of Medicine, Wrexham, UK.
Hudson
Peter
P
Hill
Diane
D
Barber
Joan
J
Lloyd
Alwyn
A
Davies
Gareth
G
Regland
Björn
B
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000097:blood*; D005492:Folic Acid / Q000097:blood; D005978:Glutathione / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D008609:Mental Status Schedule; D009483:Neuropsychological Tests; D011379:Prognosis; D012016:Reference Values; D014805:Vitamin B 12 / Q000097:blood
D006710:Homocysteine; D005492:Folic Acid; D005978:Glutathione; D003545:Cysteine; D014805:Vitamin B 12