Carriers of Alzheimer's genetic marker have greater difficulty harnessing past knowledge
August 22, 2019
Science Daily/Baycrest Centre for Geriatric Care
Adults carrying a gene associated with a higher risk of Alzheimer's disease had a harder time accessing recently acquired knowledge, even though they didn't show any symptoms of memory problems, according to findings published in a joint Baycrest-University of Oxford study.
Researchers found that older adults carrying a specific strain of the gene, apolipoprotein E4, otherwise known as APOE4, weren't able to tap into information they had just learned to assist them on a listening test.
These findings suggest greater difficulty for these individuals to access knowledge from their memory to guide their attention in ways that would have improved their performance, according to the study published in the journal Scientific Reports. This work could lead to the development of new ways to detect individuals at risk.
The research team worked with 60 research participants (aged 40 to 61) from the Oxford Biobank who had varying combinations of APOE genes -- which includes one group of individuals with a combination of APOE3/APOE4 genes, one group of individuals with a set of APOE4 genes and one group of individuals with a set of APOE3 genes. All research participants had normal hearing, scored within the normal range of cognitive assessments and completed a questionnaire about their memory.
Each research participant listened to 92 audio clips and they were told to pay attention to where the clip was coming from, whether it was presented in the left, right or both ears. After the clip was played, they were asked which side they heard the sound from and if they responded incorrectly, the sound was replayed. Participants had a one-hour break before hearing the 92 audio clips again, but this time they were asked whether there was an additional sound at the end of the clip and to press a button when they heard it. Each clip was placed twice. During the first play-through, the clip's location was replayed and during the second play-through, the additional tone was added.
The study found that no matter the APOE genotype, all older adults were able to learn the information and remember the location of the audio clip, but individuals with the APOE4 gene had greater difficulty in identifying the additional sound at the end of the clip.
"For some reason, people with the APOE4 gene were not able to take advantage of information they learned earlier, such as the expected location of the clip, to boost their performance," says Dr. Claude Alain, a senior author on the paper and senior scientist at Baycrest's Rotman Research Institute. "This study shows we have a test that is sensitive to capture problems or challenges faced by individuals with this gene, before their deficits are observed on a standard neuropsychological assessment."
This was an exciting study looking at healthy, middle-aged people who carry a gene that increases their risk of developing Alzheimer's disease by 15-fold, says Dr. Chris Butler, a senior author on the paper and an associate professor in clinical neurosciences at the University of Oxford.
"The research could lead to more sensitive methods of detecting Alzheimer's disease in its very earliest stages, the time at which treatments are most likely to be effective," says Dr. Butler. "I was delighted to carry out this work with researchers from Baycrest."
As next steps, researchers continue to explore how the brain's ability to process what is heard changes with neurodegenerative conditions, such as mild cognitive impairment.
https://www.sciencedaily.com/releases/2019/08/190822141908.htm
Dietary choline associates with reduced risk of dementia
August 6, 2019
Science Daily/University of Eastern Finland
A new study by researchers at the University of Eastern Finland is the first to observe that dietary intake of phosphatidylcholine is associated with a reduced risk of dementia. Phosphatidylcholine was also linked to enhanced cognitive performance. The main dietary sources of phosphatidylcholine were eggs and meat. The findings were published in the American Journal of Clinical Nutrition.
Choline is an essential nutrient, usually occurring in food in various compounds. Choline is also necessary for the formation of acetylcholine, which is a neurotransmitter. Earlier studies have linked choline intake with cognitive processing, and adequate choline intake may play a role in the prevention of cognitive decline and Alzheimer's disease. In fact, choline is nowadays used in a multinutrient medical drink intended for the treatment of early Alzheimer's.
The new study now shows that the risk of dementia was 28% lower in men with the highest intake of dietary phosphatidylcholine, when compared to men with the lowest intake. Men with the highest intake of dietary phosphatidylcholine also excelled in tests measuring their memory and linguistic abilities. These findings are significant, considering that more than 50 million people worldwide are suffering from a memory disorder that has led to dementia, and the number is expected to grow as the population ages. Alzheimer's disease is the most common cause of dementia, for which no cure currently exists. The new findings may, therefore, play a vital role in the prevention of dementia. Successful dementia prevention is a sum of many things and in this equation, even small individual factors can have a positive effect on the overall risk, possibly by preventing or delaying the disease onset.
"However, this is just one observational study, and we need further research before any definitive conclusions can be drawn," Maija Ylilauri, a PhD Student at the University of Eastern Finland points out.
The data for the study were derived from the Kuopio Ischaemic Heart Disease Risk Factor Study, KIHD. At the onset of the study in 1984-1989, researchers analysed approximately 2,500 Finnish men aged between 42 and 60 for their dietary and lifestyle habits, and health in general. These data were combined with their hospital records, cause of death records and medication reimbursement records after an average follow-up period of 22 years. In addition, four years after the study onset, approximately 500 men completed tests measuring their memory and cognitive processing. During the follow-up, 337 men developed dementia.
The analyses extensively accounted for other lifestyle and nutrition related factors that could have explained the observed associations. In addition, the APOE4 gene, which predisposes to Alzheimer's disease and is common in the Finnish population, was accounted for, showing no significant impact on the findings. The key sources of phosphatidylcholine in the study population's diet were eggs (39%) and meat (37%).
https://www.sciencedaily.com/releases/2019/08/190806101530.htm
Diabetes treatment may keep dementia, Alzheimer's at bay
Study finds progression of dementia and Alzheimer's signature tangles are much faster in people with untreated diabetes
March 25, 2019
Science Daily/University of Southern California
A new study comparing people with diabetes, prediabetes and normal blood sugar finds that diabetes, left untreated, could mean a higher likelihood of developing dementia, including Alzheimer's disease.
Patients on medication for type 2 diabetes may be keeping Alzheimer's disease away.
USC Dornsife psychologists have found that those patients with untreated diabetes developed signs of Alzheimer's disease 1.6 times faster than people who did not have diabetes.
The study was published March 4 in the journal Diabetes Care.
"Our findings emphasize the importance of catching diabetes or other metabolic diseases in adults as early as you can," says Daniel A. Nation, a psychologist at USC Dornsife College of Letters, Arts and Sciences. "Among people with diabetes, the difference in their rate of developing the signs of dementia and Alzheimer's is clearly tied somehow to whether or not they are on medication for it."
Nation says that this study may be the first to compare the rate of developing the pathology for Alzheimer's disease and dementia among people with normal glucose levels, with pre-diabetes, or people with type 2 diabetes -- both treated and untreated.
For the study, the scientists were comparing the "tau pathology" -- the progression of the brain tangles that are the hallmark of Alzheimer's disease. When the tangles combine with sticky beta-amyloid plaques -- a toxic protein -- they disrupt signals between brain cells, impairing memory and other functions.
Nation and Elissa McIntosh, a USC Dornsife Ph.D. doctoral candidate in psychology, analyzed data collected by the Alzheimer's Disease Neuroimaging Initiative on 1,289 people age 55 and older. Data included biomarkers for diabetes and vascular disease, brain scans and a range of health indicators, including performance on memory tests.
For some participants, Nation and McIntosh were able to analyze 10 years' worth of data, while for others, they had one or four years.
Among 900 of those patients, 54 had type 2 diabetes but were not being treated, while 67 were receiving treatment.
Most people in the study -- 530 -- had normal blood sugar levels while 250 had prediabetes (hyperglycemia).
The researchers compared, among the different diabetic patient categories, the brain and spinal fluid test results that can indicate signs of amyloid plaques and the brain tangles.
"It is possible that the medicines for treating diabetes might make a difference in the progression of brain degeneration," Nation says. "But it's unclear how exactly those medications might slow or prevent the onset of Alzheimer's disease, so that is something we need to investigate."
Increasingly, scientists regard Alzheimer's disease as the result of a cascade of multiple problems, instead of triggered by one or two. The compounding factors range from pollution exposure and genetics (the ApoE4 gene, for instance) to heart disease and metabolic disease.
The study was supported by National Institutes of Health grants R21-AG-055034, P01-AG-052350 and P50-AG-005142 and Alzheimer's Association grant AA-008369.
The Alzheimer's Disease Neuroimaging Initiative is supported by the National Institute on Aging and the National Institute of Biomedical Imaging and Bioengineering, as well as other public and private partners.
https://www.sciencedaily.com/releases/2019/03/190325122011.htm