Neuroscientists at Mayo Clinic in Florida have defined a subtype of Alzheimer's disease (AD) that they say is neither well recognized nor treated appropriately.
The variant, called hippocampal sparing AD, made up 11 percent of the 1,821 AD-confirmed brains examined by Mayo Clinic researchers — suggesting this subtype is relatively widespread in the general population. The Alzheimer's Association estimates that 5.2 million Americans are living with AD. And with nearly half of hippocampal sparing AD patients being misdiagnosed, this could mean that well over 600,000 Americans make up this AD variant, researchers say.
In an oral presentation at the annual meeting of the American Academy of Neurology in Philadelphia, scientists say hippocampal sparing AD often produces symptoms that are substantially different from the most commonly known form of AD, which affects the hippocampus, the center of memory.
The patients, mostly male, are afflicted at a much younger age, and their symptoms can be bizarre — behavioral problems such as frequent and sometimes profane angry outbursts, feelings that their limbs do not belong to them and are controlled by an "alien" unidentifiable force, or visual disturbances in the absence of eye problems, researchers say.
They also decline at a much faster rate than do patients with the most common form of AD.
"Many of these patients, however, have memories that are near normal, so clinicians often misdiagnose them with a variety of conditions that do not match the underlying neuropathology," says the study's lead author, Melissa Murray, Ph.D., an assistant professor of neuroscience at Mayo Clinic in Florida.
Many of these patients are diagnosed with frontotemporal dementia, a disorder characterized by changes in personality and social behavior, or corticobasal syndrome, characterized by movement disorders and cognitive dysfunction. Language dysfunction is also more common in hippocampal sparing AD, although patients do not have vocal or hearing deficits.
"What is tragic is that these patients are commonly misdiagnosed and we have new evidence that suggests drugs now on the market for AD could work best in these hippocampal sparing patients — possibly better than they work in the common form of the disease," Dr. Murray says.
The researchers benefit greatly from one of the largest brain banks in the country — more than 6,500 brain donations — as well as a collaborative environment between neuroscience research and neurology at Mayo Clinic, she says.
Both hallmark proteins of AD — amyloid beta (Aβ), which forms Aβ plaques, and tau, which produces tangles — are found across all subtypes of AD, including hippocampal sparing AD. The researchers developed a mathematical algorithm to classify AD subtypes using tangle counts. "What is fascinating is that all the AD patient subtypes had the same amount of amyloid, but for some reason tau tangles were found in strategic cortical regions disproportionate to the hippocampus."
In these patients, tau preferentially damages and eventually destroys neurons in parts of the brain involved in behavior, motor awareness and recognition, as well as use of speech and vision, Dr. Murray says.
She says she hopes this research, the second high-profile Mayo study to highlight hippocampal sparing AD, will "open the minds" of clinicians who are trying to diagnose dementia, helping them understand that loss of memory is not present in every AD patient.
"Our studies support the notion that dementia related to AD does not necessarily equate to a loss of memory, and points to the need for more research in amyloid and tau imaging biomarkers to help clinicians accurately diagnose AD — regardless of subtype," Dr. Murray says.
About Mayo Clinic
Recognizing 150 years of serving humanity in 2014, Mayo Clinic is a nonprofit worldwide leader in medical care, research and education for people from all walks of life. For more information, visit 150years.mayoclinic.org, MayoClinic.org or http://newsnetwork.mayoclinic.org/.
MEDIA CONTACT: Kevin Punsky, Mayo Clinic Public Affairs, 904-953-0746, Email: email@example.com
MULTIMEDIA ALERT: Video and audio are available for download on the Mayo Clinic News Network.
Kevin Punsky | Eurek Alert!
Novel anti-cancer nanomedicine for efficient chemotherapy
17.09.2019 | University of Helsinki
Researchers have identified areas of the retina that change in mild Alzheimer's disease
16.09.2019 | Universidad Complutense de Madrid
Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Hamburg and the European Molecular Biology Laboratory (EMBL) outstation in the city have developed a new method to watch biomolecules at work. This method dramatically simplifies starting enzymatic reactions by mixing a cocktail of small amounts of liquids with protein crystals. Determination of the protein structures at different times after mixing can be assembled into a time-lapse sequence that shows the molecular foundations of biology.
The functions of biomolecules are determined by their motions and structural changes. Yet it is a formidable challenge to understand these dynamic motions.
At the International Symposium on Automotive Lighting 2019 (ISAL) in Darmstadt from September 23 to 25, 2019, the Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, a provider of research and development services in the field of organic electronics, will present OLED light strips of any length with additional functionalities for the first time at booth no. 37.
Almost everyone is familiar with light strips for interior design. LED strips are available by the metre in DIY stores around the corner and are just as often...
Later during this century, around 2060, a paradigm shift in global energy consumption is expected: we will spend more energy for cooling than for heating....
Researchers from the Department of Atomically Resolved Dynamics of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg, the University of Potsdam (both in Germany) and the University of Toronto (Canada) have pieced together a detailed time-lapse movie revealing all the major steps during the catalytic cycle of an enzyme. Surprisingly, the communication between the protein units is accomplished via a water-network akin to a string telephone. This communication is aligned with a ‘breathing’ motion, that is the expansion and contraction of the protein.
This time-lapse sequence of structures reveals dynamic motions as a fundamental element in the molecular foundations of biology.
Two research teams have succeeded simultaneously in measuring the long-sought Thorium nuclear transition, which enables extremely precise nuclear clocks. TU Wien (Vienna) is part of both teams.
If you want to build the most accurate clock in the world, you need something that "ticks" very fast and extremely precise. In an atomic clock, electrons are...
10.09.2019 | Event News
04.09.2019 | Event News
29.08.2019 | Event News
17.09.2019 | Materials Sciences
17.09.2019 | Health and Medicine
17.09.2019 | Ecology, The Environment and Conservation