“It affects memory, thinking, orientation, comprehension, calculation, learning capacity, language and judgement,” according to the World Health Organization (WHO).

In a previous Maverick Life article, Looking after family members with dementia: Alzheimer’s disease, the WHO defined dementia as “a syndrome – usually of a chronic or progressive nature – that leads to deterioration in cognitive function (i.e. the ability to process thought), beyond what might be expected from the usual consequences of biological ageing.” 

Vascular dementia

While Alzheimer’s disease is the most prevalent form, accounting for 60% to 70% of dementia cases, vascular dementia is the second most common type, and is generally a result of problems with blood supply to the brain, primarily from a stroke. People might experience it differently, with varying symptoms, but it is largely characterised by problems with memory, thinking, planning, organising and decision-making. 

The brain needs blood, oxygen and nutrients to survive, and these are supplied by blood vessels, explains Professor John Joska, a neuropsychiatrist and head of the University of Cape Town’s neuropsychiatry division. The vessels reach the brain through the neck and the spine, starting off larger, becoming smaller and smaller as they penetrate the brain tissue. Due to a number of factors, these blood vessels can become blocked, or actually bleed.

“When you have blockage or bleeding from large or medium-sized blood vessels, that will commonly produce a stroke. And a stroke means that you’ve lost brain tissue in the area that is supplied by that particular blood vessel. Since the brain needs the blood to come to it, if the blood is blocked off, or if it bleeds off, that area of the brain will die. That is what a stroke is,” explains Joska.

The brain damage, or dementia, caused by such a stroke is likely to be obvious to both the patient and the doctor, often presenting with weakness, cognitive changes such as how the brain remembers, plans, processes and executes cognitive functions. 

Smaller damage too

However, vascular dementia doesn’t only result from big events such as a stroke caused by damage to large or medium-sized blood vessels. Smaller blood vessels can be damaged over time, without a person noticing until they reach old age. This can happen due to various differing conditions, including hereditary predisposition – such as in the case of people likely to have very high cholesterol through genetic causes – but it happens most commonly through what are known as vascular risk factors, which Joska describes as “things that damage the walls of the blood vessels; and it’s the same risk factors that affect the heart. Smoking, a bad diet and lifestyle, as well as uncontrolled cholesterol, uncontrolled diabetes and uncontrolled high blood pressure.”

He adds that all of these factors tend to produce inflammation and damage to the small blood vessels. However, this kind of damage doesn’t necessarily lead to a stroke because it happens in small parts of the brain, as a result the damage goes unnoticed until many areas of the brain are affected, a condition known as small vessel disease. 

Although this condition doesn’t necessarily result in a stroke, “the blood flows very slowly; it can become chalky with calcium, and then the deep tissue of the brain is poorly supplied by blood, resulting in slowing of the brain, slowing of memory, as well as slowing of the planning and thinking. While those patients don’t often have strokes, they have cognitive impairment; they become forgetful, they struggle to complete tasks, they may have language problems, and sometimes behavior problems. So in addition to the dementia caused by damage to large and medium vessels, that’s another cause of vascular dementia, small vessel disease.”

Unlike people who have had a brain scan after a large or a small stroke, Joska emphasizes that “small vessel disease often occurs very gradually, and people often don’t notice that there’s a change, until at some point, something happens, either they move house or their partner dies, or some life circumstance occurs that makes it obvious to others that this person is not able to function as highly as they could before.”

Care and prevention

There is currently no cure for dementia, and no way to reverse the brain damage, hence the focus remains largely on care, as well as treatment of conditions that might have caused the dementia, all under the guidance of a qualified medical professional. 

As per DementiaSA, a non-profit organisation that assists families, communities and health professionals who have limited access to private healthcare, “depending on the severity of the damage, with the right treatment it is possible to limit or delay the severity of the person’s decline. The important thing is to prevent further damage occurring”. So people who have been diagnosed with vascular dementia will be treated for the disease that led to the impairment. “For example, high blood pressure can be controlled through diet and lifestyle, as well as with drugs. People at risk of stroke may be prescribed drugs that thin the blood to prevent further blood clots forming.” 

That said, Joska notes that in older people, it is not always possible to arrest the disease progression, due to blood vessel damage that spans many years prior, hence the disease will continue to progress. Additionally, and particularly in older people, it will coexist with another dementia such as Alzheimer’s Disease, and treatment would have to target both in conjunction.

Importantly, it has now been established that it’s possible to significantly reduce the risk of vascular dementia through lifestyle choices, many which follow familiar advice that would be helpful in preventing a number of other conditions. In addition to having your blood pressure carefully monitored by a GP, checking it at least once a year, DementiaSA advises reducing the risk of high blood pressure, strokes and vascular dementia by not smoking, reducing alcohol to moderate levels, reducing salt and saturated fat intake, regular exercise, and having your blood fat levels measured by a GP.

Joska concurs, adding that as a rule of thumb, one should pursue a healthy lifestyle, “and a healthy lifestyle is about having regular medical checkups with your GP or primary health care provider”. It depends on your access to health care resources, obviously, “but a lot of people from 40 or 50 onwards should go for regular health checks. These would screen for common vascular risk factors and lifestyle factors that affect the arteries of the heart and brain: smoking, lifestyle, diet, cholesterol and blood pressure. It’s preventive care, and that’s the most important thing”.

A preventative approach to dementia

In 2020, the Lancet Commission published its Dementia prevention, intervention and care report, updated from the 2017 version. The document is not strictly focused on vascular dementia, but includes different dementia types, including Alzheimer’s. And rather than being a document to advise individuals, it’s meant as a guide for policymakers, to advise them on interventions to decrease the incidence of dementia worldwide.

The report concluded that more than a third of all dementias could be preventable, and identified 12 risk factors that could be modified to theoretically prevent or delay up to 40% of dementias. These are: lower education levels, hearing loss, traumatic brain injury, hypertension, excessive alcohol, obesity, smoking, depression, social isolation, physical inactivity, diabetes and air pollution. 

Based on these, the commission summarises its policy recommendations as to “prioritise childhood education for all. Public health initiatives minimising head injury and decreasing harmful alcohol drinking could potentially reduce young-onset and later-life dementia. Midlife systolic blood pressure control should aim for 130mm Hg or lower to delay or prevent dementia. Stopping smoking, even in later life, ameliorates this risk… Policymakers should expedite improvements in air quality, particularly in areas with high air pollution”.

“We recommend keeping cognitively, physically and socially active in midlife and later life, although little evidence exists for any single specific activity protecting against dementia. Using hearing aids appears to reduce the excess risk from hearing loss. 

“Sustained exercise in midlife, and possibly later life, protects from dementia, perhaps through decreasing obesity, diabetes and cardiovascular risk. Depression might be a risk for dementia, but in later life dementia might cause depression. Although behaviour change is difficult and some associations might not be purely causal, individuals have a huge potential to reduce their dementia risk.” DM/ML

In case you missed it, also read Looking after family members with dementia: Alzheimer’s disease

Looking after family members with dementia: Alzheimer’s disease

Visit Daily Maverick’s home page for more news, analysis and investigations