Cognitive Health 1/2: Preserving Your Brain's Health

This article is Part 1 of our two-part series on cognitive health across the lifespan, developed alongside our podcast episode with William Kadmiry and Anaïs Gautron.

There is a moment many of us know well. You are in the middle of a sentence, and the word you need simply does not come. You walk into a room with a clear intention, then forget why you are there. You reread the same paragraph twice without really absorbing it. You feel overstimulated more quickly, less able to hold several pieces of information in your mind at the same time.

Most of the time, we find an explanation: poor sleep, a busy week, stress, too much screen time, too many tabs open, literally and mentally. And sometimes, that is exactly what it is.

But cognitive health does not usually decline in a sudden or obvious way. It often starts to weaken more subtly: slower word recall, less stable attention, mental fatigue, reduced stress tolerance, difficulty learning or processing information as quickly as before.

These changes are easy to dismiss because they do not yet disrupt daily life. But they can also be early signs that the brain's terrain is beginning to shift.

The goal is not to fear ageing. The goal is to understand that the brain is not passive. It evolves according to the conditions we create for it.

What cognitive health really means

When we talk about cognitive health, we often think about memory. But memory is only one part of the picture.

Cognitive health also includes attention, concentration, processing speed, verbal fluency, learning capacity, decision-making, emotional regulation, creativity, and the ability to adapt to new situations.

In other words, a healthy brain is not simply a brain that remembers. It is a brain that can respond, recover, regulate, and adapt.

Cognitive decline does not always begin with obvious memory loss. It may show up as more frequent mental fatigue, difficulty concentrating, lower stress tolerance, or losing your train of thought more often.

These signs are not specific, but they may indicate that the brain is operating in a less favorable terrain: more inflammatory, less metabolically stable, more vulnerable to stress, less well nourished, less well oxygenated, or less well recovered.

Preserving cognition therefore requires looking far beyond the brain itself.

Cognitive ageing does not mean dementia

It is important to distinguish normal ageing, cognitive decline, and pathology.

With age, it is common to retrieve words a little more slowly, need more repetition to learn something new, or feel less comfortable with multitasking. As long as these changes remain moderate and do not affect autonomy, we are generally talking about normal cognitive ageing.

Cognitive decline refers to a more noticeable decrease in certain functions: memory, attention, concentration, processing speed, language, or the ability to follow a complex conversation. The person remains autonomous, but feels that their brain is less reliable, less quick, or recovers less well after stress, poor sleep, or a heavy mental load.

Pathology appears when these difficulties start to affect daily life: disorientation, difficulty managing usual tasks, language problems, impaired judgement, or progressive loss of autonomy. Alzheimer's disease and dementias belong to this category.

But the mechanisms that weaken the brain can begin long before the first visible symptoms appear. This is why prevention needs to start early.

What happens in the brain over time

The brain changes with age. That is normal.

Brain volume tends to decline progressively after midlife, and especially from the sixth decade onward. The hippocampus, a region essential for memory and spatial orientation, is particularly sensitive to ageing, inflammation, vascular dysfunction, and metabolic imbalances. The prefrontal cortex, involved in language, reasoning, and decision-making, can also be affected early.
Grey matter can decrease, cerebral blood flow can decline, and communication between neurons can become less efficient. Mitochondria may produce less energy. The brain may also become less efficient at clearing certain metabolic waste products, especially when sleep is insufficient or fragmented. At the same time, degradation of white matter tracts and myelin from the sixth decade of life also contributes to brain ageing.

In Alzheimer's disease, we observe an accumulation of beta-amyloid plaques and tau protein tangles. But these processes occur within a broader biological terrain: inflammation, oxidative stress, insulin resistance, vascular dysfunction, sleep debt, hormonal changes, nutrient deficiencies, and environmental exposures.

This is why cognitive health is not only a neurological issue. It is also a metabolic, vascular, inflammatory, hormonal, and deeply lifestyle-related issue.

The mechanisms that weaken cognitive resilience

Several biological mechanisms play a central role in cognitive ageing.

Chronic inflammation: When low-grade inflammation persists, it can affect the brain through immune activation, oxidative stress, the blood-brain barrier, and microglia, the brain's immune cells. In the short term, this can manifest as brain fog, unusual fatigue, or difficulty concentrating.
Oxidative stress and mitochondria: The brain has a very high energy demand, which makes it particularly vulnerable to oxidative stress. When oxidative stress accumulates, mitochondrial function can decline, neurotransmitter production may become less efficient, and neuronal communication can be altered. This is where nutrition becomes central: antioxidants, polyphenols, omega-3s, B vitamins, magnesium, zinc, vitamin C, and vitamin D support repair, signaling, and protection.
Insulin resistance and blood sugar instability: The brain needs energy to think, remember, concentrate, and regulate emotions. When insulin resistance develops, the brain's ability to use glucose efficiently may be impaired. This can contribute to lower brain energy, brain fog, cravings, and difficulty concentrating.
Vascular health: The brain depends on blood flow. Every neuron needs oxygen, glucose, micronutrients, and efficient waste removal. Hypertension, endothelial dysfunction, atherosclerosis, elevated ApoB, lipid metabolism disorders, and chronic inflammation can compromise cerebral perfusion over time. What protects the heart often protects the brain too.
Sleep: Sleep is one of the brain's main repair windows. It consolidates memory, regulates emotional processing, and contributes to the clearance of certain metabolic waste products through the glymphatic system, especially during deep sleep. When sleep is too short, fragmented, or non-restorative, the brain loses part of its restoration cycle.
Hormones: The brain is highly sensitive to hormonal fluctuations. Thyroid hormones influence brain energy and processing speed. Cortisol modulates memory, stress, and recovery. Insulin affects glucose use. DHEA-S has documented neuroprotective effects: it modulates neuronal plasticity and may also attenuate some of the harmful effects linked to glucocorticoids, including anxiety and depression. Estrogens and testosterone contribute to memory, mood, motivation, and neuronal plasticity. This is why hormonal imbalances can show up as brain fog, lower concentration, cognitive fatigue, increased anxiety, or reduced stress tolerance.
The gut-brain axis: The gut and brain communicate through the immune system, the vagus nerve, microbiome-derived metabolites, and inflammatory signals. When the intestinal barrier is weakened or the microbiome is imbalanced, this can influence mood, cognition, and the stress response.

Neuroplasticity: the brain's counterforce

The good news is that the brain is not fixed.

Neuroplasticity refers to the brain's ability to change, reorganize, and create new connections in response to experience, learning, repetition, environment, or injury.

It does not disappear with age, but it depends on the terrain. A brain exposed to chronic inflammation, poor sleep, nutrient deficiencies, constant stress, and metabolic dysfunction will not adapt as efficiently as a brain that is well nourished, well rested, well oxygenated, and regularly stimulated.

Several levers support neuroplasticity: aerobic exercise, by far one of the most powerful, strength training, learning new skills, deep sleep, social connection, omega-3s, polyphenols, protein, stable blood sugar, stress regulation, natural light, and circadian rhythm alignment.

One molecule often comes up in this context: BDNF, or brain-derived neurotrophic factor. It supports neuron survival, synaptic plasticity, and learning. It is influenced by physical activity, sleep, inflammation, stress, and nutrition. It also tends to decline with age.

In simple terms: the brain changes in response to what you repeat.

Early signs to observe

These signs are not diagnostic criteria. But they are worth paying attention to when they become frequent or progressive:

mental fatigue earlier in the day;
difficulty finding words, especially under stress;
losing your train of thought more often;
lower tolerance to noise, screens, or multitasking;
needing caffeine or sugar to maintain mental performance;
brain fog after meals;
reading without absorbing information;
stronger emotional reactivity and slower recovery;
waking up unrefreshed despite getting enough hours of sleep.

The goal is not to overinterpret every lapse in memory. The goal is to identify patterns.

One bad day is normal. A repeated decline in cognitive resilience is useful information.

Biomarkers that help understand the terrain

Cognitive health cannot be reduced to a blood test. But certain biomarkers can help assess the terrain that supports, or weakens, long-term brain function:

hs-CRP
Omega-3 index (EPA, DHA)
Ferritin
Homocysteine
Fasting insulin / HOMA-IR, HbA1c
ApoB, advanced lipid panel
25-OH vitamin D
Vitamin B12, folate
Thyroid markers
Cortisol and DHEA-S

These markers do not diagnose cognitive decline. They help answer a more useful question: is your brain operating in a terrain that supports resilience, repair, and mental clarity?

What to remember

Your brain does not decline overnight.

It adapts for years. It compensates. It keeps functioning despite stress, inflammation, poor sleep, blood sugar instability, nutrient deficiencies, and hormonal changes, until the load becomes harder to carry.

This is why cognitive health should not be taken seriously only once symptoms become obvious. It is built early.

In your thirties, forties, and fifties, the foundations are already being laid: metabolic health, sleep quality, vascular function, inflammation, nutrition, movement, stress management, social connection, and cognitive stimulation.

In Part 2, we move from mechanisms to action: the nutrients, dietary patterns, and habits that support neuroplasticity, mitochondrial function, and brain resilience.

🎧 Go deeper: an inflammation episode on the Lucis podcast

Brain fog, chronic fatigue, digestive troubles, skin problems, joint pain, hormonal imbalances… What if ALL these symptoms shared the same origin? Low-grade chronic inflammation is now the common denominator of most modern diseases. The term is everywhere, but almost no one really knows what it covers.

With William Kadmiry, naturopath and micronutritionist, co-founder of Naturaneo, Anaïs Gautron sets the record straight: what inflammation REALLY is, when it becomes toxic, how to spot it on a blood test, and which dietary and lifestyle levers to activate to bring it down.

Educational content only. This does not replace medical advice, diagnosis, or care.

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