Alzheimer's disease: Five things to know
Alzheimer's disease, a devastating neuro-degenerative condition that causes dementia, affects more than 30 million people worldwide and remains an illness for which there is no cure.
Ahead of World Alzheimer's Day on Wednesday, here are five things to know about an illness that was brought to the world's attention by afflicting personalities such as late US president Ronald Reagan and British fantasy author Terry Pratchett.
What is Alzheimer's?
German doctor Alois Alzheimer was credited with recognising the disease in 1906, first spotting the plaques and tangles in the brain of a dementia patient who died.
Alzheimer's progressively destroys brain tissue, robbing people of their memory, leaving them disoriented and at times unable to carry out everyday tasks.
It is also associated with dramatic mood swings and trouble communicating.
According to the World Health Organization (WHO), more than 55 million people around the world suffer from dementia, of which Alzheimer's is the most common form.
Alzheimer's represents 60 to 70 percent of dementia cases, or more than 30 million.
As life expectancy soars, the prevalence of Alzheimer's in lower- and middle-income countries is climbing. The WHO expects the number of people living with Alzheimer's to triple by 2050.
That will increase the burden on families and on healthcare systems.
Alzheimer's and dementia are among the main causes of problems with mobility and dependency for elderly people.
Alzheimer's is by far the most common form of dementia, but little is known about what precisely causes it or how it progresses.
In Alzheimer's disease, two key proteins—tau and amyloid-beta—build up into tangles and plaques—known together as aggregates—that cause brain cells to die and lead to brain shrinkage.
Little is known about what causes the proteins to appear or the link between them.
In a new study in 2021, researchers said the toxic protein clusters reach different parts of the brain early on and then accumulate over the course of decades.
The difficulty in pinpointing the precise cause of Alzheimer's, despite decades of research, has hampered the development of a treatment or cure for the illness.
The biggest advance over the past two decades came in 2021 when the United States approved a drug called Aduhelm, the first new medicine against the disease in almost two decades and the first to address cognitive decline.
However, it has limited effectiveness and medical opinion is divided over its therapeutic benefits.
Risk factors, prevention
According to the French National Institute of Health and Medical Research (Inserm), the main risk factor for Alzheimer's is age: the likelihood of getting it increases after the age of 65, rising steeply after 80.
Studies, stimulating work and an active social life all seem to delay the appearance of the first symptoms and their severity.
This is because they create a "cognitive reserve" that compensates temporarily for the lost brain cells, reflecting the plasticity of the brain and its capacity to adapt.
© 2022 AFP