New Research Helps Unravel the Risks of Developing Alzheimer’s Disease

Australian scientists are helping to unravel the links between a person’s brain chemistry, genes and their risk of developing Alzheimer’s disease (AD).
Their research, with finding presented in four papers at the Alzheimer's Association International Conference (AAIC) this week, reveals the interplay between two known AD risk factors being the build-up of amyloid plaques in the brain and a common gene variation (BDNF Val66Met).
Professor Paul Maruff, Chief Science Officer at Melbourne-based cognition testing company Cogstate, said the research also painted a picture of who is most at risk for AD.
“Our studies conducted in the Australian Imaging Biomarkers and Lifestyle (AIBL) cohort have confirmed both elevated brain amyloid and this common gene variation are risk factors for Alzheimer’s disease, with the presence of both signaling those at highest risk and patients in whom cognitive deterioration was more rapid,” said Professor Maruff, a co-author on all four papers.
“This is important because it can help to identify those with the most to gain from early drug and perhaps even behavioral intervention designed to prevent AD.  “Both approaches to prevention are currently a major international focus of companies and research groups.
“This research will also help to identify those older people who have mild cognitive impairment (MCI) but who have a low risk of AD, meaning their impairment may have other causes such as depression or stress which are more readily treatable.”
Key findings of the four studies supported by AIBL include:

•  Among healthy older people, and people who meet clinical criteria for mild cognitive impairment (MCI), high brain amyloid levels indicate that AD-related neuro-degeneration has begun and that memory will now decline at a constant rate.


• In healthy older people with abnormally high brain amyloid levels who also carry the BDNF Val66Met gene, memory and other aspects of cognition will decline faster than in those who do not carry this variant.


• Older people diagnosed with MCI, and who have normal brain amyloid levels, do not show decline in memory over time and therefore their cognitive impairment may be due to other more readily treatable causes such as depression or stress.


• The sensitivity of Cogstate’s cognition testing was also confirmed as a “useful tool for the identification of AD-related memory impairment” in clinical settings.

Prof Maruff said a clearer picture of AD risk was emerging (see chart) with around 30 per cent of Australians aged over 60 years known to have high brain amyloid levels. Among this group, around one in three will also carry the BDNF Val66Met gene variation, further increasing their AD risk.
“A better understanding of these AD-related population and biological factors places us closer to developing effective AD treatments and intervention strategies,” Prof Maruff said.