Objective: Various studies have shown an association between ABO blood
groups and both physical and mental illness. This pilot study was con
ducted to find out whether there is any association between ABO blood
groups and senile dementia of Alzheimer's type. Methods: The sample wa
s selected from 107 patients admitted to the psychogeriatric assessmen
t unit of the district psychiatric hospital over a period of one year.
All Caucasian patients of United Kingdom origin above the age of 70 w
ith confirmed diagnosis of Alzheimer's dementia according to DSM-III c
riteria who had developed dementia after the age of 65 were included (
N = 33); 74 patients were excluded for various reasons. Results: Out o
f the 33 patients there were 21 (64%) with group A, 3 (9%) with group
B, 9 (27%) with group O and none with group AB blood. Among the United
Kingdom population there were 79,334 (42%) with group A, 16,280 (9%)
with group B, 88,782 (47%) with group O and 5,781 (3%) with group AB b
lood (p = 0.038). Conclusions: Although the number of cases were not l
arge, the results of this study suggest that the prevalence of type A
blood group was greater and O was less for Caucasian Alzheimer's subje
cts than for the general population.