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103P
University of Bath Summer Meeting July 2004 |
Dementia, apoliprotein E genotypes and plasma total homocysteine in a centenarian population in Sri Lanka
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Print abstractPrevalence of dementia increases exponentially between the ages of 65-85 yrs (Hendrie, 1997). Alzheimer’s disease (AD), the commonest cause of dementia, is associated with high plasma total homocysteine (tHcy) (Smith, 2002) and the presence of apolipoprotein E4 (apoE4) genotype (Farrer et al., 1997). However, little is known about the prevalence of dementia in centenarians, and the association of plasma tHcy and apoE4 with AD in this age group.
We have studied the prevalence of dementia, and the association of plasma tHcy and apoE4 genotype with AD in a centenarian population in Sri Lanka.
20 centenarians resident in the Western province of Sri Lanka (population 5.3 million) who agreed to join the study were recruited after informed consent. Their ages were confirmed by official records. All were visited at their places of residence, and underwent detailed cognitive assessment and a brief physical and neurological examination. The carers, usually a member of family, were asked to comment on memory and activities of daily living. Diagnosis of dementia and AD were made according to established criteria. Blood was taken from 18 (two refused consent) for routine biochemistry, assessment of plasma tHcy and apoE genotype.
The average age of the study population was 102.1 ± 1.6 yrs with 11 men and 9 women. 16 lived with their families and four in care homes for elderly. All needed significant support from carers mainly due to physical handicaps. 10 out of 20 had dementia (AD 8; VaD 1; DLB 1) and one mild cognitive impairment. The apoE4 allele frequency was 31.25% in AD subjects compared with 4.8% in non-AD subjects, including 21 from our earlier report (De Silva et al., 2003) (p=0.008). The mean plasma tHcy was higher in those with AD (19.5 µmol - 1) compared to non-AD centenarian subjects (14.7 µmol - 1), but the difference did not reach significance.
The prevalence of dementia among this centenarian group was 55% with AD accounting for 72.7% of cases. While there was a tendency for high tHcy to be associated with AD, the presence of one or more alleles of apoE4 genotype was associated with AD in this centenarian cohort.
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