AAIC 2024 previewed the future of Alzheimer's and dementia prevention, care, and treatment

Every year, the Alzheimer's Association International Conference (AAIC) provides a forum for the world's leading scientists in the field of Alzheimer's disease and dementia research to come together and share their findings on the state of the science. In July 2024, individuals ranging from the globe's most experienced dementia investigators to those new to Alzheimer's and dementia research converged in Philadelphia, Pennsylvania, USA, to hear the latest discoveries in risk factors, diagnosis, treatment, care, and more at AAIC 2024.

AAIC is the world's largest gathering of dementia researchers, and clinicians AAIC 2024 broke records with the largest number of in‐person attendees – over 8600. An additional 5700‐plus joined online, for a total of over 14,400 attendees. More than half (57%) were women, and 38% were first‐time participants. One‐third were under the age of 35.

Attendees in Philadelphia and online had the opportunity to choose from more than 800 podium presentations and scientific sessions, as well as more than 3500 in‐person poster presentations and nearly 900 virtual poster presentations. Among the topics explored were the biological underpinnings of dementia, clinical study recruitment, diversification of the clinical trial pipeline, health disparities, and factors that contribute to dementia risk across the life course.

This year, more than 500 conference fellowships were awarded, by the Alzheimer's Association covering expenses such as travel, housing, or registration for those selected. The fellowships prioritize early career researchers and those from low‐ and middle‐income countries, helping them build their careers and professional connections in Alzheimer's and dementia research, care, and treatment and ensuring their representation in all discussions of scientific discovery. Conference attendees represented 101 countries from around the world.

In her welcome remarks, Alzheimer's Association President and CEO Joanne Pike, DrPH, emphasized global accomplishments and global challenges.

“Thanks to you and your peers in the global scientific community, we are making progress across the entire continuum of this disease,” said Pike. “In every year that goes by, you are building more and more understanding about how we can prevent this disease, diagnose it early, treat it, and care for those experiencing it. This progress is indeed incredible, but with progress comes the potential for significant inequities in who can benefit from the latest knowledge or latest innovation.”

Pike continued; “The Alzheimer's Association is working in partnership with global leaders and our peers in countries around the world to develop public health solutions to meet the challenges of this moment, including how we translate your work and implement it not just in countries that have the most access, but in every country around the world, so that no one is left behind.”

“As Dr. Pike mentioned, our field's evolution in the past few years is truly extraordinary,” said Maria C. Carrillo, PhD, the association's chief science officer and medical affairs lead, in her welcoming remarks. “In just a few years, we've gone from not having treatments that address the underlying biology of Alzheimer's to multiple approved treatments now being marketed in the United States and a few other countries. Although this is a celebratory moment for many of us, the moment also highlights our global challenges to ensure we bring everyone along with us [so that all have access to treatment].”

In addition to convening the world's largest gathering of dementia scientists, the Alzheimer's Association funds more Alzheimer's and dementia research than any other non‐profit organization worldwide.

“I am proud to be at an organization that is so deeply committed to supporting your work and our global scientific community,” shared Carrillo. “Earlier this month, our latest award cycle has brought our total investment in your work to $430 million working in more than 1,100 projects spanning the spectrum of dementia science in 56 countries!”

Carrillo's excitement was echoed throughout AAIC 2024 as researchers shared their discoveries with attendees and the world. What follow are some of the key stories emanating from AAIC 2024.

A blood test for alzheimer's

Dementia is often underdiagnosed, according to the 2024 Alzheimer's Disease Facts and Figures report. ¹ That could change if an accurate blood test were available for use in clinicians’ offices. Advances in blood tests are happening quickly, and many findings were reported at AAIC.

Improved accuracy

A large Swedish study, reported for the first time at AAIC 2024, and published simultaneously in JAMA shows that blood tests can do a better job of accurately detecting Alzheimer's than both primary care doctors and specialists using traditional diagnostic methods. ² In the study, 1213 patients were tested with the PrecivityAD2 test (known as APS2). It uses a combination of (1) plasma phosphorylated‐tau217 to non‐phosphorylated‐tau217 ratio (known as % p‐tau217) and (2) the ratio of two types of amyloid beta protein (Aβ42/Aβ40), and it outperformed clinicians in this study. Specifically, the results showed that among 698 individuals seen at memory clinics, APS2 was around 90% accurate at identifying Alzheimer's disease, while specialists were 73% accurate. Among 515 patients seen in primary care, APS2 was also around 90% accurate, while primary care physicians were 63% accurate. In addition, APS2 was highly accurate even in patients with comorbidities, such as kidney disease, which are common in older patients seen by primary care physicians and can affect concentrations of p‐tau217. (Sebastian Palmqvist, MD, PhD, et al. Evaluation of the prospective use of blood biomarkers for Alzheimer's disease in primary and secondary care. Funders: Alzheimer's Association, the National Institute of Aging).

Streamlining the diagnostic process

Research reported at AAIC 2024 also suggests that using high‐performing blood tests in primary care could identify potential Alzheimer's patients much earlier to be referred to Alzheimer's disease specialists and discuss appropriate care, including eligibility for new treatments. The researchers used a well‐established forecasting model to predict wait times for people eligible for treatment, accounting for both the limited number of Alzheimer's disease specialists and the growing older population. The model included the projected US population of people 55 and older from 2023 to 2032 and compared two scenarios. The first was that primary care clinicians would decide whether to refer a patient to an Alzheimer's disease specialist based on the results of a brief cognitive test. The second was that they would also factor in the results of a high‐performance blood test and assume that a blood test would be given to individuals testing positive for early‐stage cognitive impairment in primary care and that referrals to specialty care would be informed by the test results.

The model suggested that by 2033, people in the U.S. could wait an average of nearly 6 years (70 months) to understand whether they could be eligible for new Alzheimer's treatments if their primary care doctor only used brief cognitive assessments to make referrals. At the end of that period, some individuals might no longer be eligible for treatment because Alzheimer's had advanced to a stage not appropriate for approved treatments. If blood tests were used to rule out Alzheimer's, results from the modeling study suggested that the average wait times would be reduced to 13 months for Alzheimer's patients because far fewer patients would need to see a specialist.

Researchers also determined that if blood tests and brief cognitive assessments were used at the primary care level to confirm the possibility of an Alzheimer's diagnosis, wait times to understand eligibility for new treatments would fall to less than 6 months on average because of reduced demand for Alzheimer's specialists and the additional capacity now available for cerebrospinal fluid (CSF) or positron emission tomography (PET) testing. (Soeren Mattke, MD, DSc, et al. Impact of a high‐performing blood test on wait times for determination of eligibility for a disease‐modifying Alzheimer's treatment in the U.S. Funder: C2N Diagnostics).

Identifying cognitively unimpaired people for clinical trials

Including people at earlier stages of Alzheimer's in clinical trials might help identify treatments that are effective when symptoms are mild or absent. A study reported at AAIC 2024 found that p‐tau217 blood tests could be a simple and accurate selection tool for cognitively unimpaired individuals who likely have Aβ plaques in their brains. The researchers analyzed samples from 2718 cognitively unimpaired participants from 10 studies with available plasma p‐tau217 and Aβ PET imaging or CSF samples. They found that plasma p‐tau217 blood tests predicted (with 79% to 86% accuracy) the likelihood that a cognitively unimpaired person would also test positive for Aβ pathology on an amyloid PET scan or CSF test. Adding the results from the Aβ CSF test or an Aβ PET scan to an analysis after a positive blood sample increased prediction accuracy to 90% or higher and increased confidence in the ability of the plasma p‐tau217 test to identify the presence of amyloid in the brain. (Gemma Salvadó, PhD, et al. Use of plasma p‐tau217 as a pre‐screening method for detecting amyloid‐PET positivity in cognitively unimpaired participants: A multicenter study. Funders: Alzheimer's Association, European Union's Horizon 2020 Research and Innovation Program under Marie Sklodowska‐Curie action, Alzheimerfonden, Strategic Research Area MultiPark).

Future considerations

Though all of these results are promising, currently no single test can determine with 100% accuracy whether a person is living with Alzheimer's or another dementia. Doctors will still need to use a combination of diagnostic tools, along with medical history, to make an optimal diagnosis. When considering the use of a blood test, the Alzheimer's Association Appropriate Use Recommendations for Blood Biomarkers in Alzheimer's Disease would be a helpful tool to guide decision‐making for clinical and research purposes. ³

To help guide healthcare professionals in incorporating blood tests for Alzheimer's into clinical practice, the Alzheimer's Association has convened a panel of clinical and subject‐matter experts, partner organizations, and patient representatives to lead the preparation of clinical practice guidelines. The goal is to build guidelines that distill the best available evidence and translate it into clear and actionable recommendations. The guidelines will be followed by clinical tools, educational courses, and resources.

Treatments: Repurposed drugs for alzheimer's

Alzheimer's and other dementias are complex diseases, and future treatments will likely require combinations of therapies that address the diseases in multiple ways. In addition to lecanemab and donanemab, US Food and Drug Administration‐approved drugs for the treatment of early symptomatic Alzheimer's, scientists are exploring whether drugs approved for other health conditions may be repurposed to protect brain health.

One group of drugs under consideration is glucagon‐like peptide‐1 (GLP‐1) receptor agonists, which can help people manage diabetes, lose weight, and lower their risk of heart disease, stroke, and kidney disease. They work by mimicking the natural hormone glucagon‐like peptide, which is released by the stomach after eating. Recent studies with animal models suggest that some GLP‐1 receptor agonists may protect the brain by reducing early forms of Aβ, normalizing the brain's processing of glucose, and improving memory and learning.

Data from a phase 2b clinical trial of the GLP‐1 receptor agonist liraglutide were presented at AAIC 2024. While the clinical trial did not meet its primary endpoint of change in the cerebral glucose metabolic rate in the cortical regions of the brain (hippocampus, medial temporal lobe, and posterior cingulate), the results suggest that liraglutide may protect the brains of those with mild Alzheimer's disease. In the clinical trial, cognitive decline was slowed by as much as 18% after 1 year of treatment, compared with placebo. It also reduced shrinking by nearly 50% in parts of the brain that affect memory, learning, language, and decision‐making compared with placebo. (Paul Edison, MD, PhD, et al. Evaluation of novel GLP‐1 analogue in the treatment of Alzheimer's disease. Funding: Alzheimer's Society, UK; Alzheimer's Drug Discovery Foundation, Novo Nordisk AS, John and Lucille Van Geest Foundation, National Institute for Health and Care Research (NIHR) Biomedical Research Centre).

Risk factors

Though age is the greatest risk factor for Alzheimer's, researchers are studying an array of other factors that may play an important role in disease risk. Some of these factors may be modified to reduce the risk of Alzheimer's. Research studies presented at AAIC 2024 shed light on some of these potentially modifiable risk factors.

Wildfire smoke

Exposure to wildfire smoke may increase the risk of being diagnosed with dementia, according to a large, 10‐year study reported for the first time at AAIC 2024. Study researchers reported that the risk of dementia was notably stronger from wildfire smoke than from other sources of fine particulate matter air pollution (PM_2.5), such as motor vehicles and factories. PM_2.5 is a microscopic mixture of solid and liquid droplets in the air that is 30 times smaller than the width of an average human hair. High levels of PM_2.5 have also been shown to increase the risk of heart disease, asthma, and low birth weight.

The study team analyzed health records from more than 1.2 million socioeconomically diverse Kaiser Permanente Southern California members 60 years or older. None of the members had been diagnosed with dementia at the beginning of the study. Researchers used air quality monitoring data, satellite imagery, and machine learning techniques to separate wildfire and non‐wildfire PM_2.5. They found that the risk of dementia was higher due to wildfire smoke, even with less exposure than to other sources of PM_2.5. Specifically, they observed a 21% increase in the odds of dementia diagnosis for every increase of 1 microgram per meter – or μg/m³, which is the amount of particulate matter in a cubic meter of air – in the 3‐year average wildfire PM_2.5 exposure. Comparatively, they determined that study participants had only a 3% increased risk of dementia diagnosis for every increase of 3 μg/m³ in the 3‐year average of non‐wildfire PM_2.5 exposure.

Study investigator Holly Elser, MD, PhD, of the University of Pennsylvania, Philadelphia, noted several reasons why PM_2.5 produced by wildfires might be more hazardous to health. These include that the smoke has a greater concentration of toxic chemicals and, on average, a smaller diameter than PM_2.5 from other sources, making it easier for the PM_2.5 to enter the body.

“Previous research has found that exposure to PM_2.5 is associated with dementia, but in light of our large, long‐term study, it's apparent the risk from exposure due to wildfire smoke is an even bigger concern,” said Elser. “Air pollution produced by wildfires now accounts for more than 70% of total PM_2.5 exposure on poor air quality days in California. This is a real problem.”

Study investigator Joan A. Casey, PhD, of the University of Washington, Seattle, added, “The findings appeared most pronounced among individuals from racially and ethnically minoritized groups and in high poverty areas. These findings underscore that clinical and health policies seeking to prevent dementia‐associated disparities should include efforts to reduce exposure to long‐term wildfire and non‐wildfire PM_2.5.” (Holly C Elser, MD, PhD, et al. Long‐term wildfire smoke exposure and incident dementia in a large California cohort. Funding: the U.S. National Institute on Aging R01‐AG071024).

Processed red meat

Research suggests that eating an overall heart‐healthy diet may contribute to reduced risk for cognitive decline and dementia. Managing one's diet involves avoiding foods that may contribute to declining brain health. According to research reported for the first time at AAIC 2024, people who eat about two servings a week of processed red meat have a 14% higher risk of dementia than those who eat less than about three servings a month. The study also showed that replacing one serving of processed red meat every day with one serving of nuts and legumes can lower the risk of dementia by about 20%. Examples of processed red meat include bacon, bologna, hot dogs, and sausage. Conducted at the Harvard T.H. Chan School of Public Health in Boston, the study analyzed findings over time from more than 130,000 participants in the Nurses’ Health Study and Health Professionals Follow‐Up Study. Researchers based their findings on the participants’ answers to food‐frequency questionnaires. Each additional daily serving of processed red meat was linked to an extra 1.6 years of cognitive aging for global cognition and an extra 1.7 years of cognitive aging in verbal memory. However, replacing one daily serving of processed red meat with one daily serving of nuts and legumes was linked to 1.37 fewer years of aging in global cognition. The researchers also studied unprocessed red meat and did not find a significant association between dementia and eating unprocessed red meat, such as hamburgers, steak, or pork chops. (Yuhan Li, MHS, et al. A prospective study of long‐term red meat intake, risk of dementia, and cognitive function in US adults. Funding: National Institutes of Health R01AG077489, R00DK119412, RF1AG083764, R01NR01999, and P30DK046200; the Nurses' Health Study was supported by the NIH UM1 CA186107, and the Health Professionals Follow‐Up Study was supported by the NIH U01 CA167552).

Awards

In addition to being a forum for the presentation of new discoveries in Alzheimer's and dementia science, AAIC is a platform for recognizing individuals whose discoveries have made a significant difference in the field. Several individuals were recognized at AAIC 2024.

Bill thies award

The Bill Thies Award for Distinguished Service to the International Society to Advance Alzheimer's Research and Treatment (ISTAART) recognizes an ISTAART member who has provided continued and outstanding service to the ISTAART community. The Thies Award honors William (Bill) Thies, PhD, who was instrumental in launching ISTAART, which since its inception in 2008 has grown to over 13,000 members across 129 countries. Steven T. DeKosky, MD, is the recipient of the 2024 Bill Thies Award. He is the Aerts‐Cosper Professor of Alzheimer's Research at the University of Florida (UF) College of Medicine, professor of neurology and neuroscience at UF, deputy director of the McKnight Brain Institute, and senior advisor to the Florida Alzheimer's Disease Research Center (ADRC). DeKosky was also director of the University of Pittsburgh ADRC for over 14 years, and he was the founding chair of ISTAART.

Inge grundke‐iqbal award

Tara Spires‐Jones, DPhil, FMedSci, is this year's recipient of the Inge Grundke‐Iqbal Award for Alzheimer's Research. This award is presented to the senior author of the most impactful study published in Alzheimer's research during the two calendar years preceding AAIC. “Synaptic Oligomeric Tau in Alzheimer's Disease—A Potential Culprit in the Spread of Tau Pathology Through the Brain” was published in Neuron. ⁴ Spires‐Jones is Personal Chair of Neurodegeneration and Director of the Centre for Discovery Brain Sciences at the University of Edinburgh. Spires‐Jones is president of the British Neuroscience Association and founding editor of the translational neuroscience journal Brain Communications.

Blas frangione early career achievement award

Eduardo Zimmer, PhD, is the 2024 recipient of the Blas Frangione Early Career Achievement Award. This award recognizes early‐career researchers whose cutting‐edge research in Alzheimer's and dementia has the potential to impact the field by propelling it in novel directions. Zimmer is Assistant Professor at Universidade Federal do Rio Grande do Sul (UFRGS), Brazil, Adjunct Professor at McGill Centre for Studies in Aging, Montreal, Canada, and Associate Researcher at the Brain Institute (Brazil). His research focuses on understanding the cellular origins of Alzheimer's, with a particular interest in neuroimaging, brain energy metabolism, and astrocytes.

AAIC lifetime achievement awards

The AAIC Lifetime Achievement Awards are named in honor of Henry Wisniewski, MD, PhD; Khalid Iqbal, PhD; and Bengt Winblad, MD, PhD, cofounders of the International Conference on Alzheimer's Disease, now known as the Alzheimer's Association International Conference. These awards honor significant contributions to Alzheimer's and dementia research, through either a single scientific discovery or a body of work.

Ralph A. Nixon, MD, PhD, is the recipient of the Khalid Iqbal Lifetime Achievement Award. Nixon is Professor of Psychiatry and Cell Biology at the New York University Grossman School of Medicine and Director of the Center for Dementia Research at the Nathan S. Kline Institute, New York. Nixon's principal research focuses on the biology of protein clearance in the brain by endosomal‐lysosomal, autophagy, and calpain‐calpastatin systems. His team has identified molecular defects in these clearance mechanisms that are central to the pathogenesis of Alzheimer's disease and related disorders.

Ricardo Nitrini, PhD, is the recipient of the Henry Wisniewski Lifetime Achievement Award. Nitrini is senior Professor of Neurology and Head of the Neurological Clinical Division at Hospital das Clínicas da FMUSP (HC‐FMUSP). His main area of research is cognitive and behavioral neurology with an emphasis on the study of dementia. He is the founder and co‐director of the Cognitive and Behavioral Neurology Group of the Department of Neurology and the founder of the Reference Center for Cognitive Disorders at HC‐FMUSP.

Goldie S. Byrd, PhD, is the recipient of the Bengt Winblad Lifetime Achievement Award. Byrd is Professor of Social Sciences and Health Policy and Director of the Maya Angelou Center for Health Equity at Wake Forest University School of Medicine. She conducts research on the genetics of Alzheimer's disease in people of African descent. A primary focus of her work is the inclusion of special populations, particularly Black Americans, in Alzheimer's research and clinical trials. At North Carolina A&T State University, Byrd founded the Center for Outreach in Alzheimer's Aging and Community Health.

AAIC 2025

Be sure to mark your calendars for AAIC 2025 (aaic.alz.org), July 27 to 31, 2025, in Toronto, Canada, and online. Abstract and session submission opens in December 2024 and closes in January 2025. Registration opens in March 2025.