What are the causes of the disease?
“The origin of Alzheimer’s disease is linked to two types of brain lesions: amyloid deposits and neurofibrillary degeneration. The presence of these abnormal protein clusters results in an environment that is unfavorable for communication between neurons (brain cells), thus disrupting the passage of information,” explains Dr. Marion Lévy, Head of Studies and Research at the Fondation Vaincre Alzheimer. This contributes, among other things, to the loss of neurons and then cognitive functions.
Thanks to research, we now know that the disease is caused by other dysregulations in the brain. This is why we speak of a disease with multiple factors. Among them, neuroinflammation or inflammation of the brain. “Amyloid deposits that accumulate between nerve cells can also trigger an immune system reaction,” continues Dr. Lévy. The brain’s immune cells (microglia) then become overactive and release substances that cause chronic inflammation. This creates a toxic environment for neurons, disrupting communication between cells. »
In Alzheimer’s disease, nerve cells in the brain also experience significant metabolic disruption, which contributes to their dysfunction and progressive death.
What are the two new risk factors identified?
“In 2020, a scientific article (1) identified 12 modifiable risk factors which could prevent or delay up to 40% of cases of neurocognitive diseases, including Alzheimer’s disease, underlines Dr. Lévy. These factors are linked to different stages of life and include level of education, head injuries, physical inactivity, smoking, excessive alcohol consumption, hypertension, obesity, diabetes, loss of hearing, depression, social isolation and air pollution. » The article emphasizes the fact that these factors are avoidable or modifiable by changes in lifestyle, behavior or medical interventions.
In 2024, in this same scientific journal, the author added two new modifiable risk factors: vision loss and high cholesterol. “With this addition, 45% of Alzheimer’s cases could now be avoided. »
Is Alzheimer’s disease hereditary?
On distingue two forms of Alzheimer’s disease : the sporadic form (more than 99% of cases) and a familial/hereditary form which concerns less than 1% of cases. “This is rare and generally appears before the age of 65 (sometimes as early as 30-40). It is linked to mutations in three genes (APP, PSEN1 and PSEN2). If a person inherits one of these mutations, they will almost certainly develop the disease, with a 50% transmission to their descendants. » These families, when they are known, are followed.
On the other hand, the hereditary form should not be confused with genetic risk factors. “Other genes, such as APOE ε4, increase the probability of developing the disease, but do not guarantee its occurrence. Having one copy of APOE ε4 increases the risk of having Alzheimer’s disease compared to the general population, and having two copies (one from each parent) increases this risk even more. »
What are the three stages of the disease?
“Before really talking about Alzheimer’s disease, we will already be talking about mild cognitive disorders, probably due to Alzheimer’s disease,” continues the specialist. Once these disorders become major, we can in fact distinguish three stages (beginner, moderate and severe) which depend on the severity of the symptoms.
• The beginner stage is marked by memory problems for recent events: difficulty remembering events, conversations that took place a short time ago or the names of people. “There can also be problems with concentration, planning and organization,” indicates Marion Lévy of the Vaincre Alzheimer Foundation. At this stage, the patient can still live alone.
• At the moderate stageother symptoms begin to appear, such as difficulty manipulating certain objects, language disorders, difficulty finding words. We can also have spatial and temporal disorientation and reasoning disorders. “The patient begins to have difficulty living alone and requires assistance to make his life easier. »
• At the severe stageall these symptoms intensify. “Daily life becomes very difficult (the person can no longer carry out the simplest tasks, such as eating, washing or moving around without help). This is also true for the caregiver,” concedes the neuroscientist. This is often when institutionalization occurs.
How does Alzheimer’s disease end?
Alzheimer’s disease usually causes severe decline in cognitive, physical and vital functions. “Among these numerous complications, there are, for example, swallowing problems (which can cause pneumonia that the patient will have difficulty fighting), cardiac arrest, malnutrition (because the patient will not think about eating), falls…, explains Dr. Lévy. All these problems intensify with the progression of the disease, and will indirectly lead to death. »
In the terminal phase, care focuses primarily on comfort and symptom management (palliative care). The goal is pain relief and emotional support for the sick person and their family.
What is the life expectancy with this disease?
After the diagnosis of Alzheimer’s disease, life expectancy is generally between 10 and 20 years depending on the patient. This duration depends on several factors:
• Age at diagnosis. “Young patients will generally have more rapid progression of the disease, which may be slower in older patients,” notes Dr. Lévy.
• The stage at the time of diagnosis. “If the disease is diagnosed early, when it is still in a mild stage, it is possible to maintain a better quality of life for several years with appropriate care and medical support. » However, once the disease is advanced, with severe loss of memory and other cognitive functions, life expectancy is shorter.
• Comorbidities. Alzheimer’s patients who have other health problems, such as heart disease, infections, or metabolic disorders (such as diabetes), may live shorter lives than those who do not.
Are there any treatments?
There is no treatment to cure Alzheimer’s disease, but some aim to slow the progression of symptoms and improve quality of life.
“Since the early 2000s, treatments (called anticholinesterase drugs) have aimed to treat cognitive symptoms only,” explains Dr. Lévy. They were dereimbursed in 2018 in France, so patients are obliged to pay them. On the other hand, two new treatments have recently appeared to directly target the causes of the disease and change its course.” These two immunotherapies (Leqembi® and Kisunla™) will thus eliminate amyloid deposits, therefore acting directly on one of the causes of the disease. But they are not yet authorized on the market in Europe.
In addition, non-drug solutions can be implemented such as speech therapy sessions, the intervention of specialized Alzheimer’s teams who will call on psychomotor therapists, occupational therapists, etc. “Day centers will also offer mental exercises and activities aimed at maintaining cognitive functions. »
(1) Published in the scientific journal The Lancet.
