Alzheimer’s disease is a condition that develops silently for up to 10 years before it can be diagnosed and treated. A French team has managed to identify symptoms that can appear more than 15 years before the disease becomes clinically evident.
Alzheimer’s disease affects nearly 5.8 million people over 65 in the US. It particularly affects older people: it is very rare before the age of 65 and affects nearly 15% of people over 80. Alzheimer’s disease is a neurodegenerative disease. Nerve cells slowly degenerate, leading to a series of progressive symptoms. The most well-known symptom of the disease is memory loss. But this is not the only symptom: patients also have problems with executive functions and orientation in time and space. Today, the disease is neither curable nor preventable. Knowledge of the early symptoms of Alzheimer’s disease is very patchy. By the time a patient is diagnosed, the disease is too often already advanced.
A study of 80,000 people
A French team published the results of a study of 80,000 patients in the prestigious journal The Lancet. Half of them developed Alzheimer’s disease, while the other half formed a control group and never developed a neurodegenerative disease during the period studied.
The authors tested the association between disease onset and 123 health factors using statistical analysis. The results showed a correlation between a list of 10 conditions and the incidence of Alzheimer’s disease within 15 years. The first of these conditions was depression, followed by anxiety, high-stress exposure, hearing loss, constipation, cervical spondyloarthritis, memory loss, fatigue, falls, and sudden weight loss. Some of these conditions were already known to predispose patients to develop Alzheimer’s disease, such as depression or hearing loss. Others much less so, such as cervical spondyloarthritis or constipation.
Statistical links only
The authors emphasize that their study shows only statistical links, which is not evidence of cause and effect. An in-depth study of the underlying mechanisms is still needed.
In addition, the cited study does not allow us to know whether depression is a precondition for Alzheimer’s disease or whether depression is an early symptom of the disease. However, this kind of information is still very useful to better understand the disease and try to prevent it.
In the near future, the authors will extend their analysis to a larger number of patients (26 million!) and to other degenerative diseases such as Parkinson’s disease, Charcot disease, and multiple sclerosis.