Amyloid plaques are extracellular deposits of the amyloid beta (Aβ) protein mainly in the grey matter of the brain. Degenerative neuronal elements and an abundance of microglia and astrocytes can be associated with amyloid plaques. Some plaques occur in the brain as a result of aging, but large numbers of plaques and neurofibrillary tangles are characteristic features of Alzheimer's disease. The plaques are highly variable in shape and size; in tissue sections immunostained for Aβ, they comprise a log-normal size distribution curve, with an average plaque area of 400-450 square micrometers (μm2). The smallest plaques, which often consist of diffuse deposits of Aβ, are particularly numerous. Plaques form when Aβ misfolds and aggregates into oligomers and longer polymers, the latter of which are characteristic of amyloid.
Cerebral amyloid angiopathy (CAA) is a form of angiopathy in which amyloid beta peptide deposits in the walls of small to medium blood vessels of the central nervous system and meninges. The term congophilic is sometimes used because the presence of the abnormal aggregations of amyloid can be demonstrated by microscopic examination of brain tissue after staining with Congo red. The amyloid material is only found in the brain and as such the disease is not related to other forms of amyloidosis.
In neuropathy, primary progressive aphasia (PPA) is a type of neurological syndrome in which language capabilities slowly and progressively become impaired. As with other types of aphasia, the symptoms that accompany PPA depend on what parts of the brain's left hemisphere are significantly damaged. However, unlike most other aphasias, PPA results from continuous deterioration in brain tissue, which leads to early symptoms being far less detrimental than later symptoms.
Tauopathies are a class of neurodegenerative diseases characterized by the aggregation of abnormal tau protein. Hyperphosphorylation of tau proteins causes them to dissociate from microtubules and form insoluble aggregates called neurofibrillary tangles. Various neuropathologic phenotypes have been described based on the anatomical regions and cell types involved as well as the unique tau isoforms making up these deposits. The designation 'primary tauopathy' is assigned to disorders where the predominant feature is the deposition of tau protein. Alternatively, diseases exhibiting tau pathologies attributed to different and varied underlying causes are termed 'secondary tauopathies'. Some neuropathologic phenotypes involving tau protein are Alzheimer's disease, frontotemporal dementia, progressive supranuclear palsy, and corticobasal degeneration.
In medicine, proteinopathy, or proteopathy, protein conformational disorder, or protein misfolding disease, is a class of diseases in which certain proteins become structurally abnormal, and thereby disrupt the function of cells, tissues and organs of the body.
Paratonia is the inability to relax muscles during muscle tone assessment. There are two types of paratonia: oppositional and facilitatory. Oppositional paratonia ("gegenhalten") occurs when subjects involuntarily resist passive movements, while facilitatory paratonia ("mitgehen") occurs when subjects involuntarily assist with passive movements. Both types of paratonia have been associated with cognitive impairment or mental disorders, particularly in relation to frontal lobe dysfunction. Paratonia is frequently encountered in association with dementia.
The prevention of dementia involves reducing the number of risk factors for the development of dementia, and is a global health priority needing a global response. Initiatives include the establishment of the International Research Network on Dementia Prevention (IRNDP) which aims to link researchers in this field globally, and the establishment of the Global Dementia Observatory a web-based data knowledge and exchange platform, which will collate and disseminate key dementia data from members states. Although there is no cure for dementia, it is well established that modifiable risk factors influence both the likelihood of developing dementia and the age at which it is developed. Dementia can be prevented by reducing the risk factors for vascular disease such as diabetes, high blood pressure, obesity, smoking, physical inactivity and depression. A study concluded that more than a third of dementia cases are theoretically preventable. Among older adults both an unfavorable lifestyle and high genetic risk are independently associated with higher dementia risk. A favorable lifestyle is associated with a lower dementia risk, regardless of genetic risk. In 2020, a study identified 12 modifiable lifestyle factors, and the early treatment of acquired hearing loss was estimated as the most significant of these factors, potentially preventing up to 9% of dementia cases.
Gregory A. Petsko is an American biochemist and member of the National Academy of Sciences, the National Academy of Medicine, the American Academy of Arts and Sciences, and the American Philosophical Society. He is currently Professor of Neurology at the Ann Romney Center for Neurologic Diseases at Harvard Medical School and Brigham and Women's Hospital. He formerly had an endowed professorship in Neurology and Neuroscience at Weill Cornell Medical College and is still an adjunct professor of Biomedical Engineering at Cornell University, and is also the Gyula and Katica Tauber Professor, Emeritus, in biochemistry and chemistry at Brandeis University. On October 24, 2023, in a ceremony in the East Room of the White House, President Joe Biden presented Gregory Petsko and eight others with the National Medal of Science, the highest honor the United States can bestow on a scientist and engineer.
Steven T. DeKosky is the Aerts-Cosper Professor of Alzheimer's Research at the University of Florida (UF) College of Medicine, deputy director of UF’s Evelyn F. and William L. McKnight Brain Institute (MBI) and associate director of the 1Florida Alzheimer’s Disease Research Center.
Alzheimer's disease (AD) is a neurodegenerative disease that usually starts slowly and progressively worsens, and is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems with language, disorientation, mood swings, loss of motivation, self-neglect, and behavioral issues. As a person's condition declines, they often withdraw from family and society. Gradually, bodily functions are lost, ultimately leading to death. Although the speed of progression can vary, the average life expectancy following diagnosis is three to twelve years.
Sundowning, or sundown syndrome, is a neurological phenomenon associated with increased confusion and restlessness in people with delirium or some form of dementia. It is most commonly associated with Alzheimer's disease but is also found in those with other forms of dementia. The term sundowning was coined by nurse Lois K. Evans in 1987 due to the timing of the person's increased confusion beginning in the late afternoon and early evening. For people with sundown syndrome, a multitude of behavioral problems begin to occur and are associated with long-term adverse outcomes. Sundowning seems to occur more frequently during the middle stages of Alzheimer's disease and mixed dementia and seems to subside with the progression of the person's dementia. People are generally able to understand that this behavioral pattern is abnormal. Research shows that 20–45% of people with Alzheimer's will experience some variation of sundowning confusion. However, despite lack of an official diagnosis of sundown syndrome in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), there is currently a wide range of reported prevalence.
Samuel E. Gandy, is a neurologist, cell biologist, Alzheimer's disease (AD) researcher and expert in the metabolism of the sticky substance called amyloid that clogs the brain in patients with Alzheimer's. His team discovered the first drugs that could lower the formation of amyloid.
Florbetaben, sold under the brand name Neuraceq, is a diagnostic radiotracer developed for routine clinical application to visualize β-amyloid plaques in the brain. It is a fluorine-18 (18F)-labeled stilbene derivative.
Michael D. Geschwind is a professor of neurology at the UCSF Memory and Aging Center (MAC), specializing in neurodegenerative disorders.
LATE is a term that describes a prevalent medical condition with impaired memory and thinking in advanced age, often culminating in the dementia clinical syndrome. In other words, the symptoms of LATE are similar to those of Alzheimer's disease.
Mathias Jucker is a Swiss neuroscientist, Professor, and a Director at the Hertie Institute for Clinical Brain Research of the University of Tübingen. He is also a group leader at the German Center for Neurodegenerative Diseases in Tübingen. Jucker is known for his research on the basic biologic mechanisms underlying brain aging and Alzheimer's disease.
Dena Dubal is the David A. Coulter Endowed Chair in Ageing and Neurodegenerative Disease at University of California, San Francisco. Dubal has demonstrated that the hormone Klotho can enhance cognition and protect the brain from neurodegenerative decline.
Rachelle Smith Doody is an American neurologist and neuroscientist. She is known for her work on late stage development of drugs for Alzheimer’s disease, Parkinson’s disease, Huntington’s disease and other neurodegenerative disorders.
Andrew E. Budson is an American neurologist, academic and researcher. He is a Professor of Neurology at Boston University School of Medicine, Lecturer in Neurology at Harvard Medical School, Chief of Cognitive and Behavioral Neurology and Associate Chief of Staff for Education at the Veterans Affairs (VA) Boston Healthcare System, where he also serves as a Director of the Center for Translational Cognitive Neuroscience. He is Associate Director and Outreach, Recruitment, and Engagement Core Leader at the Boston University Alzheimer's Disease Research Center.
Howard H Feldman is a professor of neurosciences at the University of California, San Diego (UCSD). He was appointed director of the Alzheimer's Disease Cooperative Study (ADCS) in April 2016, a national grant-funded network and coordinating center that was established in 1991. He holds the Epstein Family Chancellor’s Chair in Alzheimer’s Disease Research at UC San Diego. Prior to joining UC San Diego, he was on faculty at University of British Columbia where he served as the Head of the Division of Neurology, the Director of the Alzheimer’s and Related Disorders Clinic and the Executive Associate Dean for Research for the Faculty of Medicine.
