Population ageing and the consequences of the pandemic will significantly increase the prevalence of mental illnesses in the years to come. Investment will be essential to cover existing needs and develop new treatments, in particular against Alzheimer’s disease.

Often reduced to psychiatric diseases, mental health actually covers a much larger field. Anxiodepressive disorders, developmental disorders, neurocognitive disorders, etc. A billion human beings could suffer from these disorders. Little known, underestimated and sometimes stigmatised, more than 500 mental ailments with various consequences are currently listed. According to the WHO, their prevalence continues to increase over time. The disease of the century, depression affects 350 million people a year. A rampant epidemic, dementia affects nearly 55 million people. As the population ages, dementia will affect 139 million people in 2050. In low- and middle-income countries, three-quarters of sufferers are not treated.

Social, economic and human costs

The social and economic costs of mental health are particularly high. According to the WHO, those directly linked to dementia reached USD 1.3 trillion in 2019. They are expected to double by 2030. A relatively optimistic estimate which does not take into account the many direct and indirect impacts of the pandemic, which are still difficult to accurately quantify (see box). The problem is not new. Two years before the health crisis, the National Institute of Mental Health had already highlighted the harmful effects of not taking care of mental health and drug addiction. The financial weight for American companies was then estimated at between USD 80 and 100 billion per year. At the same time, the National Alliance on Mental Illness estimated the loss of productivity of a worker with unresolved depression to be 35%.

The main international organisations are clear: mental health is a profitable investment. For every dollar invested in the large-scale treatment of common mental disorders like depression and anxiety, the gain in health and productivity is multiplied by five. Behind these strategic issues, mental health remains a cause of premature death. According to the WHO, the life expectancy of patients is reduced from ten to twenty years.

Improve prevention and screening

Although very different, serious mental disorders all have one thing in common: there is no cure. A number of treatments nevertheless succeed in reducing the symptoms, or even slowing down the degeneration process (see box). According to specialists, screening is currently the best way to prevent the onset of mental disorders, which is not always possible. In Parkinson’s disease, the performance of clinical diagnosis at an early stage is estimated to be between 50 and 70%. A European study1 nevertheless tends to show that a simple nasal swab test could detect the disease several years before the first symptoms appear.

Rapidly growing technological progress could contribute to this early detection. Among other levers, artificial intelligence should play a major role, as a study by the University of San Francisco suggests2. From a simple analysis of brain scanners, their algorithm can detect the presence of this disease six years before humans, on average. Another significant example: an algorithm being developed at a California university3 is now able to detect three different forms of autism during pregnancy with 100% accuracy.

New treatment avenues

Despite the difficulties encountered, research into mental illnesses is not slowing down. Some scientific projects are even charting new therapeutic perspectives. American and Hungarian researchers4 in particular succeeded in balancing the communication between two types of neurons of the prefrontal cortex thanks to specific mRNAs. A major breakthrough that could lead to the development of new remedies for schizophrenia, depression and autism spectrum disorders.
On another issue, a team of researchers from the University of Copenhagen5 may have found a way to cross the blood-brain barrier to allow certain neuroprotective compounds to reach the brain using nanoparticles. Successfully tested in mice, this discovery could radically improve the effectiveness of drugs used to treat epilepsy, Parkinson’s and Alzheimer’s.

Even more concrete, a molecule indicated for the treatment of symptoms of benign prostatic hyperplasia would decrease the chances of developing Parkinson’s disease. According to the results of an observational study conducted in Denmark and the United States6, the risk level would drop from 12 to 37%. Confident of their findings, researchers now want to confirm these results in a randomised clinical trial.
On the front line, investors will naturally play a decisive role in carrying out all of these projects. A public health actor, Candriam will identify and support the most relevant and useful initiatives for the community. Through its network of experts, it will promote companies that will produce the solutions of tomorrow.

Alzheimer’s: a first for twenty years!

A first since... 2003. Twenty years after the authorisation of the last treatment against Alzheimer’s disease in the United States, the FDA approves a new drug. Officially approved last June, aducanumab has the particular ability to slow the cognitive decline of treated patients. Considered a breakthrough innovation, this human monoclonal antibody has benefited from an accelerated authorisation procedure, a privilege granted to products that provide significant therapeutic benefits compared to existing treatments. As a result of the numerous research work conducted in recent years, several drugs should soon complete the therapeutic arsenal: 126 molecules are currently in clinical development, including 28 in phase III. The health needs are considerable. They will increase further in the years to come, with population ageing and the impacts of the pandemic. According to the World Alzheimer Report, 100 million people will be affected by Alzheimer’s disease in 2050, compared to 35 million in 2015.


Mental illnesses: the impacts of the crisis

The direct and indirect impacts of the pandemic on mental health are still difficult to assess, but they have worsened an already precarious health situation, especially among children and adolescents. According to the WHO, there will be “long-term and far-reaching consequences”. The first pieces of evidence are accumulating in the international scientific literature. Among other revelations, a study published in The Lancet Psychiatry reveals that people with psychotic disorders, mood disorders, addictions or mental retardation have a higher risk of developing a severe form of the disease. A source of disruption or interruption of essential mental health services, Covid-19 is also associated with the onset of psychiatric disorders, as shown by an Italian study. The pandemic will inevitably leave its mark on people around the world. According to a British study, 34% of recovered patients develop a neurological or psychiatric disorder within six months of infection.


(1) “Alpha-synuclein seeds in olfactory mucosa of patients with isolated REM sleep behaviour disorder”, Brain (April 2021).
(2) “A deep learning model to predict a diagnosis of Alzheimer disease by using F-FDG PET of the brain”, Radiology (November 2018).
(3) “Risk assessment analysis for maternal autoantibody-related autism (MAR-ASD): a subtype of autism”, Molecular Psychiatry (January 2021).
(4) “Cell Surface Protein mRNAs Show Differential Transcription in Pyramidal and Fast-Spiking Cells as Revealed by Single-Cell Sequencing”, Cerebral Cortex (July 2020).
(5) “Post-capillary venules are the key locus for transcytosis-mediated brain delivery of therapeutic nanoparticles”, Nature Communication (July 2021).
(6) “Association of Glycolysis-Enhancing α-1 Blockers With Risk of Developing Parkinson Disease”, JAMA Neurology (February 2021).