Changes in Apolipoprotein Levels Identified Over the Lifespan

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Age- and sex-related differences in plasma levels of apolipoprotein have been examined by researchers at the Centre for Healthy Brain Ageing (CHeBA), UNSW Sydney, to explore their potential contribution to physical and cognitive health, in subjects in the second 50 years of life and including centenarians. The study was published in the journal, Neurobiology of Aging.
 
The study suggested that levels of some apolipoproteins are associated with lifespan and cognitive function in exceptionally long-lived individuals, according to lead author Dr Julia Muenchhoff. 
 
Prior to this study, it was unclear how levels of apolipoproteins differed with age, particularly in the 50+ age group, and whether these associations remain stable, diminish or increase with age. The research measured seven plasma apolipoproteins (ApoA1, ApoA2, ApoB, ApoC3, ApoE, ApoH and ApoJ) in over 1000 individuals aged from 56 to 105 years from the Sydney Centenarian Study and Sydney Memory & Study run by CHeBA, and the Hunter Community Study run by the University of Newcastle. 
 
“We found that plasma levels of all seven apolipoproteins modestly decreased with age from mid-life in a linear manner, except for ApoE and ApoJ, for which we observed U-shaped curves, reflecting a trend to higher ApoE and ApoJ levels in those aged over 95 years. Higher levels of these two apolipoproteins in exceptionally long-lived individuals seems related to an extended life span.” said co-author and leader of CHeBA’s Proteomics group, Dr Anne Poljak.
 
Previous research indicates that apolipoproteins, a family of proteins which play a crucial role in vascular and immune functions, have both protective and risk effects for cognitive decline and Alzheimer’s disease (AD) in the elderly. People with a particular form of the gene for the ApoE protein (APOE ε4) have previously been identified as having a higher risk of late onset Alzheimer’s disease. The current study found the proportion of people with this variant of the APOE ε4 gene was significantly lower in the centenarian population. 
 
A number of sex-related differences were also identified. 
 
“We found that plasma levels of all apolipoproteins except ApoH were higher in females than in males,” said Dr Poljak. Sex- and age-related differences were apparent in the association of apolipoproteins with cognitive performance, as only women had significant negative associations of ApoB, ApoE, ApoH and ApoJ in mid-life, whereas associations at older age were non-significant or positive.”
 
CHeBA’s Co-Director Professor Perminder Sachdev said that the findings highlight a number of apolipoproteins as targets for future studies exploring the mechanisms that contribute to extended life span and healthy cognition in later life.
 
Media contact: Heidi Douglass, Centre for Healthy Brain Ageing,
+61 2 9382 3398, 0435 579 202 | h.douglass@unsw.edu.au
Date Published: 
Thursday, 15 June 2017
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