hen we hear mention of the word, ‘cholesterol’ it invariably triggers bad connotations. It gets a bad rap because it is implicated with a narrowing of our arteries, heart disease and stroke, to name just a few nasties. So, over time we’ve been conditioned to think of all cholesterol as bad. In actual fact, this fat-like substance is critical to the healthy functioning of our bodies, being an integral part of the membranes (or walls) of every cell within our bodies. Cholesterol is absolutely critical to the structure of a healthy brain and nervous system. The myelin coating of every nerve cell (neuron) and nerve fibre (axon) in our bodies, which acts in the same way an insulating cover does around electric wires, relies heavily cholesterol for its production.
The connection and flow of information between neurons occurs across ‘synapses’ and the more of these we have, the healthier our brain and cognitive abilities are. The neurodegenerative process of Alzheimer’s causes these connections to break-down and the neurons themselves to die. Cholesterol is crucial to the formation of these synapses. So why then would high cholesterol be a risk factor for Alzheimer’s?
When we experience high levels of cholesterol in our blood serum, our arteries are much more prone to being ‘clogged up’ by a build-up of cholesterol plaques on their arterial walls. This in turn causes what we know as hypertension, or high blood pressure due to the physical blockage and therefore harder work the arteries must exert to move the blood through. Blood flow is gradually impaired to critical parts of the body including the heart and brain.
In general, when our heart muscles contract our arteries are under physical pressure to pump the blood to the rest of our bodies. When this ‘systolic’ pressure is high and in combination with this increased level of cholesterol in the blood, there is an associated increased risk of Alzheimer’s.
The following three papers give a detailed explanation of the role cholesterol plays in the brain, both pro- and anti-inflammatory (the differing levels of ‘good’ and ‘bad’ cholesterol), the effects of a high-cholesterol diet on the brain and also how cholesterol has been shown to impair the clearance of amyloid-beta plaques (one of the hallmark proteins in the clinical pathology of Alzheimer’s) from the brain and increase the process of neurodegeneration:
- Barbero-Camps, Elisabet et.al. “Cholesterol Impairs Autophagy-Mediated Clearance of Amyloid Beta While Promoting Its Secretion.” Autophagy 14.7 (2018): 1129–1154. PMC.
- Chen Y, et.al. Pro- and Anti-inflammatory Effects of High Cholesterol Diet on Aged Brain. Aging and Disease. 2018;9(3):374-390
- Martín MG, et.al. Cholesterol in brain disease: sometimes determinant and frequently implicated. EMBO Reports. 2014;15(10):1036-1052.
I’m starting to sound a bit like a cracked record. You’ve seen most of these risk reducing measures before, but I hope that this will highlight just how critical a healthy lifestyle is to reducing our risk of developing Alzheimer’s. A healthy diet and being physically active, along with the flow-on effect of maintaining a healthy weight, are critical to a healthy brain and body – what is good for the heart in general is good for the brain.
To summarise again, if you can commit to following these scientifically proven lifestyle rules, you will help to reduce your risk of developing Alzheimer’s:
Eat heart-healthy food by reducing saturated fats, eliminating trans fats, eating foods rich in omega-3 fatty acids and increasing soluble fibre
Exercise and increase your physical activity
If you smoke, quit
Maintain a healthy weight
Drink wine in moderation
Seek medical advice if cholesterol levels remain high as medication may be required.