Apolipoprotein E polymorphism and Alzheimer disease: The Indo-US Cross-National Dementia Study.
BACKGROUND
The APOE*E4 allele of the gene for apolipoprotein E (APOE) has been reported as a risk factor for Alzheimer disease (AD) to varying degrees in different ethnic groups.


OBJECTIVE
To compare APOE*E4-AD epidemiological associations in India and the United States in a cross-national epidemiological study.


METHODS
Case-control design within 2 cohort studies, using standardized cognitive screening and clinical evaluation to identify AD and other dementias and polymerase chain reaction to identify APOE genotyping.


METHODS
Rural community samples, aged 55 years or older (n=4450) in Ballabgarh, India, and 70 years or older (n=886) in the Monongahela Valley region of southwestern Pennsylvania.


METHODS
Criteria of the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association for probable and possible AD and Clinical Dementia Rating (CDR) scale for dementia staging.


RESULTS
Frequency of APOE*E4 was significantly lower (P<.001) in Ballabgarh vs the Monongahela Valley (0.07 vs 0.11). Frequency of probable or possible AD, with CDR of at least 1.0, in the Indian vs US samples, was as follows: aged 55 to 69 years, 0.1% (Indian sample only); aged 70 to 79 years, 0.7% vs 3.1%; aged 80 years or older, 4.0% vs 15.7%. Among those aged 70 years or older, adjusted odds ratios (95% confidence interval) for AD among carriers of APOE*E4 vs noncarriers were 3.4 (1.2-9.3) and 2.3 (1.3-4.0) in the Indian and US samples, respectively, and not significantly different between cohorts (P=. 20).


CONCLUSIONS
This first report of APOE*E4 and AD from the Indian subcontinent shows very low prevalence of AD in Ballabgarh, India, but association of APOE*E4 with AD at similar strength in Indian and US samples. Arch Neurol. 2000.
Ganguli
M
M
Western Psychiatric Institute and Clinic, 3811 O'Hara St, Pittsburgh, PA 15213-2593, USA. gangulim@msx.upmc.edu
Chandra
V
V
Kamboh
M I
MI
Johnston
J M
JM
Dodge
H H
HH
Thelma
B K
BK
Juyal
R C
RC
Pandav
R
R
Belle
S H
SH
DeKosky
S T
ST
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics*; D016022:Case-Control Studies; D015331:Cohort Studies; D003431:Cross-Cultural Comparison; D005260:Female; D006801:Humans; D007194:India; D008297:Male; D008875:Middle Aged; D010414:Pennsylvania; D011110:Polymorphism, Genetic / Q000235:genetics*; D012307:Risk Factors; D012424:Rural Population; D016896:Treatment Outcome; D014481:United States
D001057:Apolipoproteins E