Medical Minute: What causes dementia?
Last Updated: Jan 18 2025
Table of Contents
Almost 50% of dementia is preventable according to the latest research published in the Lancet.
What causes dementia, if so much is preventable?
This article explains the causes of dementia from two perspectives:
What happens at the microscopic level in the brain and,
What happens at the individual level in the person
The science reviewed in this article underpins what we do at aldora and our belief in the immense power of prevention.
The Microscopic Cause
Dementia occurs when abnormal proteins build up in the brain.
The type of proteins involved vary depending on the type of dementia, which is one reason finding a cure has been so challenging. For instance, Alzheimer’s Disease is linked to beta-amyloid plaques and tau tangles, while Lewy Body Dementia involves a protein called alpha-synuclein (read more about the different types of dementia here).
These proteins disrupt communication between brain cells, leading to symptoms such as memory loss, difficulty finding words, personality changes, or even hallucinations.
Over time, proteins damage brain cells and eventually cause them to shrink, a process known as “atrophy.”
The whole process happens very slowly, with proteins building up 10 to 30 years before symptoms appear and taking another 8 to 12 years to spread throughout the brain, in the case of Alzheimer’s disease.
On top of this, symptoms can be made worse if someone also has brain cell damage from reduced blood flow from clogged arteries or strokes, known as “vascular dementia”.
Lack of blood flow can also cause damage to brain cells. When this happens with Alzheimer’s disease, it’s known as “mixed dementia”.
The Individual Cause
Not all individuals with protein or stroke damage will go on to have symptoms.
Researchers have made a shocking discovery - you can have extensive protein build-up or stroke damage without symptoms of dementia.
In fact, for many people who have beta-amyloid in their brain, they will never go on to develop clinical Alzheimer’s Disease.
This is believed to be due to something called “cognitive reserve”.
At the individual level, dementia symptoms are caused by an imbalance between the strength of your brain and the amount of damage that has happened over a lifetime.
This. Is. Huge.
What happens at a microscopic level does not guarantee that at an individual level you will go on to have dementia, as long as you’re able to keep your brain balanced.
The microscopic changes are important for researchers and the pharmaceutical industry looking for an ultimate cure to the disease, but for most of us, what matters most is whether we have symptoms of the disease.
This brings us to the obvious question - how can we maintain our brain balance to avoid clinical disease?
Aldora’s 18 for Dementia Prevention
Aldora’s 18, covered in this article, can help you avoid dementia symptoms by both building up the strength of your brain and reducing things that cause damage.
Stroke-damage is primarily caused by heart-health risk factors (like smoking, cholesterol, and high blood pressure, blood sugar, or weight), which were discussed here.
Protein-damage is more common in those with a genetic link (eg. ApoE ε4 allele), making it even more important that those with the gene or strong family history build strength and reduce other forms of damage.
Timing Matters
As we discussed in the medical minute on neuroplasticity, you can change and heal your brain.
However, the best time to do it is when the damage is just starting - 10 to 30 years before you develop clinical symptoms.
Once the damage has caused cell-death and atrophy, it becomes harder and harder to build strength that is strong enough to overcome those changes.
This is why starting early is ideal. This includes when you have:
No damage (normal cognition)
The inklings of damage (mild cognitive impairment)
Early damage (early dementia)
Once you are in moderate stages of dementia, the focus shifts to managing the changes and planning for the future, as unfortunately there is very little we can do at this time to stop the spreading of damage throughout the brain.
In Closing…
Dementia is caused at the microscopic level by stroke-damage and protein-damage, which both cause cell-death and shrinking of the brain.
However, you may never actually experience symptoms of dementia if you are able to build enough strength or reduce the damage before it’s too late.
To get access to all our guidance on managing all 18 dementia prevention targets, become a member.
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Key references:
Dementia prevention, intervention, and care: 2024 report of the Lancet standing commission (Livingston et al, Lancet, 2024, found here).
Combining modifiable risk factors and risk of dementia: a systematic review and meta-analysis. (Peters et al, BMJ Open, 2019, found here).
Healthy aging and dementia: findings from the Nun Study. (Snowden D, Annals of Internal Medicine, 2003, found here).
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