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Higher HDL-C levels may curb Alzheimer's disease risk
 
 
  www.theheart.org
December 16, 2010
 
"Higher levels of HDL-C (defined as >55 mg/dL) were associated with a decreased risk of both probable and possible AD after multivariate adjustment for confounding factors. There was a definite threshold effect, the researchers say, with a clear reduction in AD risk for people in the highest HDL-C level quartile (>56 mg/dL)."
 
New York, NY - High levels of HDL cholesterol may help protect older adults from late-onset Alzheimer's disease (AD), new research suggests [1]. Dyslipidemia and late-onset AD are common in older adults in Western populations, but despite numerous studies, it remains unclear whether dyslipidemia increases the risk of AD, Dr Christiane Reitz (Columbia University, New York, NY) and colleagues report in the December 2010 issue of the Archives of Neurology.
 
The findings of the current study contrast with a prior study by the same researchers [2], which involved 1168 participants recruited from the same community in 1992 to 1994 and showed no association between HDL-C and AD, they note. They suggest the differing findings could be due to better cardiovascular health and use of lipid-lowering statins in the most recent cohort.
 
Threshold effect: Clear reduction in Alzheimer's risk for highest quartile of HDL-C The new study examined the association of lipid profiles and AD in 1130 Medicare recipients aged 65 and older with no history of dementia or cognitive impairment at baseline from 1999 through 2001.
 
During 4469 person-years of follow-up, clinicians diagnosed 89 cases of probable AD and 12 cases of possible AD. The mean age at onset of probable and possible dementia was 82.9 years and 83.1 years, respectively. Compared with subjects who did not develop dementia, those who did were more often Hispanic and had a higher prevalence of diabetes at baseline.
 
Higher levels of HDL-C (defined as >55 mg/dL) were associated with a decreased risk of both probable and possible AD after multivariate adjustment for confounding factors. There was a definite threshold effect, the researchers say, with a clear reduction in AD risk for people in the highest HDL-C level quartile (>56 mg/dL).

Hazard ratios adjusted for age, sex, education, ethnic group, APOE e4 genotype, and vascular risk factors (diabetes, hypertension, heart disease, body-mass index, and lipid-lowering treatment)
 
Higher levels of total cholesterol, non-HDL-C, and LDL-C were also associated with decreased risk of AD in analyses adjusting for age, sex, education, ethnic group, and APOE e4 genotype. However, these associations became nonsignificant after adjustment for vascular risk factors or lipid-lowering treatment.
 
Almost a quarter of contemporary cohort on statins, with higher HDL-C levels Compared with the earlier cohort, the current one had a higher proportion of subjects on lipid-lowering treatment (23.4% vs 14.5%), higher mean HDL-C levels (48.3 vs 47.2 mg/dL), and fewer individuals who smoked (9.4% vs 10.6%) or had heart disease (18.8% vs 34.1%).
 
"We believe that this is why the inverse relation of HDL-C level with AD risk was not statistically significant in the 1992-1994 cohort and is significant in the 1999-2001 cohort," say Reitz et al.
 
Related links
 
· Smoking, high blood pressure, and diabetes may lead to dementia [Prevention > Prevention; Aug 20, 2009]
 
· Elevated cholesterol in midlife increases dementia risk [Lipid/Metabolic > Lipid/Metabolic; Aug 11, 2009]
 
· Heart disease linked to poor cognitive function in middle age [Brain/Kidney/Peripheral > Brain/Kidney/Peripheral; Jul 23, 2008] Low HDL-C associated with poor memory [Brain/Kidney/Peripheral > Brain/Kidney/Peripheral; Jun 30, 2008]
 
 
 
 
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