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: firstname.lastname@example.org
MULTIMEDIA ALERT: Video and audio are available for download on the Mayo Clinic News Network.
Kevin Punsky | Eurek Alert!
Natural metabolite can suppress inflammation
01.07.2016 | ITMO University
Benign bacteria block mosquitoes from transmitting Zika, chikungunya viruses
01.07.2016 | University of Wisconsin-Madison
Densified regions with drastically reduced internal motion either act as crystal precursors or cluster and frustrate all further dynamics
Glasses are neither fluids nor crystals. They are amorphous solids and one of the big puzzles in condensed matter physics. For decades, the question of how...
Since the completion of the human genome an important goal has been to elucidate the function of the now known proteins: a new molecular method enables the investigation of the function for thousands of proteins in parallel. Applying this new method, an international team of researchers with leading participation of the Technical University of Munich (TUM) was able to identify hundreds of previously unknown interactions among proteins.
The human genome and those of most common crops have been decoded for many years. Soon it will be possible to sequence your personal genome for less than 1000...
3D printing revolutionized the manufacturing of complex shapes in the last few years. Using additive depositing of materials, where individual dots or lines...
R2D2, a joint project to analyze and development high-TRL processes and technologies for manufacture of flexible organic light-emitting diodes (OLEDs) funded by the German Federal Ministry of Education and Research (BMBF) has been successfully completed.
In contrast to point light sources like LEDs made of inorganic semiconductor crystals, organic light-emitting diodes (OLEDs) are light-emitting surfaces. Their...
High resolution rotational spectroscopy reveals an unprecedented number of conformations of an odorant molecule – a new world record!
In a recent publication in the journal Physical Chemistry Chemical Physics, researchers from the Max Planck Institute for the Structure and Dynamics of Matter...
30.06.2016 | Event News
28.06.2016 | Event News
09.06.2016 | Event News
01.07.2016 | Physics and Astronomy
01.07.2016 | Earth Sciences
01.07.2016 | Medical Engineering