Two new tools to better understand cognitive disorders
On World Alzheimer’s Disease Day, the Integrated Memory Clinic highlights two new developments recently introduced into its clinical practice and research projects.
On the occasion of World Alzheimer’s Disease Day, our Integrated Memory Clinic highlights two new developments recently introduced into our clinical practice and research projects. They illustrate an important evolution in our understanding of neurodegenerative diseases: similar symptoms can sometimes conceal different biological mechanisms… and, in some cases, several mechanisms may coexist in the same person.
A blood test to detect the biological signs of Alzheimer’s disease
We can now measure a protein called pTau217 in the blood, thanks to the work of the LHUB and Prof. Fleur Wolff.
Its increase is closely associated with the brain changes characteristic of Alzheimer’s disease, particularly the presence of amyloid pathology (a disease caused by an abnormal accumulation of proteins in the organs). The performance of this blood biomarker has improved considerably in recent years, to the point that it now plays an increasingly important role in international recommendations.
The benefit for patients is significant: a simple blood test can, in certain situations, provide information that previously required a lumbar puncture or a specialised imaging examination.
However, it is important to note that this is not a screening test for Alzheimer’s disease in the general population.
pTau217 measurement is a specialised examination performed in patients with cognitive impairment and after an initial medical assessment. It supplements the information provided by the patient interview, cognitive tests and, depending on the situation, brain imaging.
When all these elements already strongly and specifically suggest Alzheimer’s disease, pTau217 can provide the additional piece of information that strengthens the diagnosis, while sometimes making it possible to avoid a lumbar puncture. It is indeed difficult to establish a diagnosis based solely on this examination. It should nevertheless be noted that, for other neurodegenerative diseases, pTau217 does not provide the information obtained by analysing cerebrospinal fluid through a lumbar puncture.
In a way, the icing on the diagnostic cake…
What if several diseases were behind the same symptoms?
A second new development concerns a protein called alpha-synuclein. With the support of Lewy.be, and in collaboration with the Clinique Saint-Pierre d'Ottignies and Mr Jean-Louis Bayart, we have begun analysing alpha-synuclein in cerebrospinal fluid. Alpha-synuclein is a protein naturally present in the brain. In certain diseases, it adopts an abnormal form and gradually accumulates in nerve cells. These diseases are called synucleinopathies. They include, in particular, Parkinson’s disease and abnormal movements and Lewy body disease.
New techniques make it possible to detect in cerebrospinal fluid the presence of abnormal forms of alpha-synuclein capable of aggregating. This examination is currently used mainly in a research context, and its result must always be interpreted together with other clinical and paraclinical data. Why is it of such interest to us? Because our understanding of neurodegenerative diseases is changing.
For a long time, we tended to consider Alzheimer’s disease, Lewy body disease and other neurodegenerative diseases as clearly separate entities. We now know that several pathological processes can coexist in the brain of the same person.
Thus, studies conducted on the brain after death and new studies using biomarkers suggest that approximately one third of patients with Alzheimer’s disease also have alpha-synuclein-related pathology. In other words, for some patients, the question may not simply be: “Is this Alzheimer’s disease or Lewy body disease?” but rather: “Are we dealing with co-pathology in this patient?” Identifying these different components could, in the future, help us better understand each patient’s symptoms and their progression and, we hope, provide increasingly personalised care.
Towards increasingly precise neurology
Ultimately, these two new developments pursue the same objective: looking beyond symptoms in order to better understand the biological mechanisms responsible for cognitive impairment in each patient. A blood test that can sometimes avoid a lumbar puncture. An analysis of cerebrospinal fluid that helps us uncover diseases that were previously difficult to identify during the patient’s lifetime. Two different advances, but the same direction: a more precise, less invasive and more personalised diagnosis