Every year in March, Brain Awareness Week brings together scientists, clinicians and healthcare organizations from around the world to share advances in neuroscience with the general public. This 2026 edition, from March 16 to 22, highlights a concept at the heart of recent discoveries: neuroplasticity - the remarkable capacity of the adult brain to change, adapt and create new neuronal connections throughout life. Contrary to the long-held belief that the adult brain was fixed, contemporary neuroscience demonstrates that our everyday choices literally shape our brains.
Cognitive health isn't just a concern for the elderly: it's built from mid-adulthood onwards, if not earlier. Habits adopted at 30, 40 or 50 have a measurable impact on brain function at 70 and beyond. Understanding the mechanisms of cerebral plasticity and the concrete levers for maintaining it is a form of long-term investment in one's own quality of life.
Neuroplasticity: how the brain constantly remodels itself
Neuroplasticity refers to the mechanisms by which the brain modifies its structure and function in response to experience, learning, injury or disease. It is expressed at several levels: at synaptic level, by the strengthening or weakening of connections between neurons according to the Hebbian principle - neurons that activate together connect together - and at structural level, by the formation of new neurons in certain regions such as the hippocampus, a phenomenon known as adult neurogenesis.
Neuroplasticity peaks during childhood and adolescence, but does not disappear in adulthood. It remains active throughout life, conditioned by the demands placed on the brain. A regularly stimulated brain - through learning, exercise, social interaction and novelty - maintains and develops its connections. A brain that receives little stimulation, through chronic stress or lack of sleep, on the other hand, sees certain connections weaken and neurodegenerative processes accelerate.
Physical exercise: the brain's first drug
If a single factor were to be chosen to protect and improve cognitive health, it would be aerobic physical activity. Its impact on the brain has been documented with exceptional scientific rigor. Regular aerobic exercise increases the production of BDNF - Brain-Derived Neurotrophic Factor - a protein which acts as a neuronal fertilizer: it promotes neurogenesis in the hippocampus, strengthens existing synaptic connections and protects neurons against degenerative processes. Functional MRI studies have shown that physically active people have a significantly larger hippocampus - the central brain structure for memory - than sedentary people of the same age.
Current recommendations for brain health are 150 minutes of moderate-intensity aerobic activity per week - brisk walking, cycling, swimming, dancing - ideally spread over the week rather than concentrated over the weekend. Sessions of 30 to 45 minutes seem optimal for maximizing BDNF release. Muscular resistance training provides additional benefits, particularly for executive functions such as planning, inhibition and cognitive flexibility.
Sleep: when the brain cleans and consolidates
Sleep is one of the most underestimated pillars of cognitive health. During deep sleep, the glymphatic system - the brain's lymphatic system - is activated and eliminates metabolic waste accumulated during wakefulness, including the beta-amyloid and tau proteins associated with Alzheimer's disease. An inadequate night's sleep results in a measurable accumulation of these proteins, and chronic sleep deprivation is one of the best-documented risk factors for accelerated cognitive decline.
REM sleep - the dream phase - plays an essential role in the consolidation of emotional and procedural memories, and in emotional regulation. Deep slow-wave sleep consolidates declarative memories - facts and events. Both phases are essential. An adult needs between seven and nine hours' sleep a night for these consolidation and cleansing processes to take place effectively. Sleep hygiene - regular hours, a cool, dark bedroom, limiting the use of screens before bed - is a direct investment in long-term brain health.
Cognitive stimulation and brain reserve
The concept of cognitive reserve refers to the brain's ability to tolerate damage - whether age-related or caused by neurodegenerative diseases - before clinical symptoms appear. A high cognitive reserve, built up over a lifetime through education, professional complexity and intellectual activities, delays the clinical expression of diseases such as Alzheimer's by several years, even in the presence of the same load of brain pathology. In other words, two brains with the same level of amyloid lesions will not necessarily express the same symptoms, depending on their cognitive reserve.
Building and maintaining cognitive reserve involves continuous learning - a new language, a musical instrument, a professional or craft skill - intellectually demanding activities, reading, strategy games, and any activity that takes the brain out of its routine comfort zone. Novelty and complexity are particularly powerful stimuli for neuroplasticity.
Social ties, stress and brain health
Social isolation is one of the best-documented risk factors for cognitive decline and dementia - its impact on mortality is comparable to that of smoking. Social ties stimulate the brain, activate reward circuits, reduce stress hormones and create an emotional safety net. Maintaining rich and diverse social relationships is an active form of cognitive protection. Conversely, chronic stress is neurotoxic: excess cortisol damages the hippocampus, reduces neurogenesis and accelerates brain ageing. Stress management practices - mindfulness meditation, yoga, cardiac coherence, physical activity - have neuroprotective effects that can be measured on MRI.
Frequently asked questions about cognitive health and neuroplasticity
At what age should you start looking after your cognitive health?
The sooner the better - but it's never too late. Lifestyle habits that protect the brain have a beneficial impact at any age. However, epidemiological data show that risk factors for dementia accumulate over decades, and that preclinical brain damage begins to develop 15 to 20 years before the first cognitive symptoms appear. Adopting good habits in one's forties or fifties has a well-documented neuroprotective impact. People starting out in their 60s and 70s also benefit from these habits - neuroplasticity remains active at all ages.
Are memory games and brain applications really effective?
Brain gym« applications generally improve performance in the specific tasks practiced - but this benefit transfers little to general cognitive abilities or daily life. Neuroscientists speak of limited transfer. The activities that most benefit overall cognitive health are those that combine novelty, complexity, active engagement and real learning - learning a language, playing an instrument, practicing a new discipline. They call on several brain networks simultaneously and generate broader neuroplasticity than the repetition of standardized exercises.
Is it possible to medically assess cognitive health?
Yes, a medical assessment of cognitive health includes a clinical interview, the use of standardized tests - MoCA, MMSE - and, depending on the clinical picture, a blood test to exclude treatable causes of cognitive decline such as hypothyroidism, vitamin B12 or folate deficiency, untreated sleep disorders or certain medications. Brain imaging may be requested if necessary. In many of our branches in Quebec, this type of assessment can be performed without a long waiting list or a family doctor.
Can stress really damage the brain permanently?
Acute, one-off stress is normal and even useful - it mobilizes cognitive and physical resources in the face of a challenge. It's chronic stress - prolonged activation of the hypothalamic-pituitary-adrenal axis and persistent elevation of cortisol - that is neurotoxic. MRI studies have documented a reduction in hippocampal volume in people exposed to severe and prolonged chronic stress. These changes are partially reversible with effective stress management and appropriate interventions. All the more reason to take the symptoms of burnout or chronic anxiety seriously and seek help without delay.
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