Total serum homocysteine in senile dementia of Alzheimer type.
OBJECTIVE
The main hypothesis was that subtle vitamin B12 deficiencies occur more commonly in senile dementia of Alzheimer type (SDAT) that in healthy elderly individuals, and may be revealed by elevated total serum homocysteine (tHcy). A subsidiary hypothesis was that such deficiencies would be nutritionally independent as determined by retinol binding protein (RBP).


METHODS
A prospective case-controlled survey.


METHODS
A Welsh urban psychogeriatric assessment centre and local general practice.


METHODS
Thirty patients, aged 65 or over, seen consecutively in 1994 with features compatible with DSM-III-R criteria for primary degenerative dementia of Alzheimer type and 30 cognitively intact age-matched control subjects.


METHODS
Diagnosis was assessed using the CAMDEX. Cognitive scores were evaluated with the CAMCOG scale for patients and MMSE scores for control subjects. THcy was measured using high performance liquid chromatography (HPLC), and RBP assayed by a radial immunodiffusion method.


RESULTS
Patients had a highly significant elevation of tHcy compared with control (p < 0.0001). Multiple regression highlighted the interrelated effects of tHcy and total serum cobalamin on cognitive scores. RBP did not differ between groups. Macrocytosis was absent, and neutrophil hypersegmentation uncommon, in hyperhomocysteinaemic patients.


CONCLUSIONS
SDAT patients have significantly elevated tHcy. This is independent of RBP determined nutritional status. 'Classical' haematological changes of cobalamin or folate deficiency are poor predictors of tHcy in these patients. Aberrant cobalamin tissue delivery appears to contribute to SDAT cognitive decline. Relative contributions of other tHcy determinants require further investigation.
McCaddon
A
A
Wrexham Maelor Hospital, North Wales, UK. andrew@mccaddon.demon.co.uk
Davies
G
G
Hudson
P
P
Tandy
S
S
Cattell
H
H
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood* / Q000175:diagnosis / Q000209:etiology; D001693:Biological Transport, Active; D016022:Case-Control Studies; D003071:Cognition / Q000502:physiology; D003404:Creatinine / Q000097:blood; D004032:Diet; D005260:Female; D005492:Folic Acid / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D008568:Memory / Q000502:physiology; D011446:Prospective Studies; D011569:Psychiatric Status Rating Scales; D012016:Reference Values; D012044:Regression Analysis; D018709:Statistics, Nonparametric; D014805:Vitamin B 12 / Q000097:blood*; D014806:Vitamin B 12 Deficiency / Q000150:complications
D006710:Homocysteine; D005492:Folic Acid; D003404:Creatinine; D014805:Vitamin B 12