The man took a bus to work every morning. On one journey, he became confused and disoriented. Not knowing where he was, he alighted quickly. Looking around him, he was still not able to recognise his surroundings but managed to call his children to pick him up. After that incident, he became increasingly confused and forgetful. He was later diagnosed with vascular dementia, which isassociated with impaired blood flow to the brain.

While his cognitive decline was sudden and out of proportion, for some patients with vascular dementia, the symptoms can come on more gradually, said Dr Simon Ting, Senior Consultant, Department of Neurology, National Neuroscience Institute (SGH Campus).

Vascular dementia, the most common type of dementia after Alzheimer’s disease, mostly occurs after a stroke. The symptoms of the two neurological conditions may overlap but the latter is more commonly associated with age-related changes in the brain, while vascular dementia can occur at an earlier age, in the 40s. “Stroke is the most common cause of vascular dementia. Physical weakness, slurred speech can come with stroke; typically, within about three months, patients start to show cognitive decline,” said Dr Ting.

Not all patients who suffer a stroke have similar symptoms. Some experience very mild cognitive impairment, while others face major impairments. Under computer tomography (CT) or magnetic resonance imaging (MRI), the brain may show poor blood supply in clusters of small, multiple vessels; a large, single vessel; or deep areas of the brain. “There are many types of vascular dementia, so the presentation can be quite varied,” said Dr Ting.

While stroke is the main cause — about half of all vascular dementia cases are due to stroke — vascular dementia can be due to other causes; in other words, blockage in the brain not due to stroke and genes. For the former, the patient may have heart valve issues, which lead to a blood clot travelling to the brain and causing a blockage.

Faulty genes can also put people at high risk of vascular dementia. “A condition called CADASIL (Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy) presents a genetic cause of vascular dementia where the walls of small or mid-sized blood vessels thicken, limiting blood flow,” said Dr Ting.

Another is where a copy of the ApoE4 (apolipoprotein E4) gene is inherited from both parents. “That means both parents have ApoE4, you get both from them, then your chance of developing dementia is eight times higher than those without it, and there’s a chance that your brain will have a lot of ischaemic changes, a lot of vascular changes,” he added.

While both CADASIL and ApoE4 are rare, some people can be more prone to vascular events. In such cases, it is important to bring down the risk of such events by following a healthy lifestyle. “The most important message is that vascular dementia is common because of its direct relevance to vascular risk factors, and the ultimate way to reduce the risk of vascular dementia is to have a healthy lifestyle,” said Dr Ting. “At the end of the day, healthy living helps reduce the risk of getting heart disease, reduces the risk of getting a stroke, and reduces the risk of getting vascular dementia.”

Vascular dementia is related to the socalled vascular burden or risk factors affecting the vascular system — hypertension or high blood pressure, diabetes, smoking, excessive weight, and having a sedentary lifestyle. These conditions can affect or compromise blood circulation to the brain, potentially causing strokes and damage to parts of the brain responsible for certain cognitive functions and, consequently, vascular dementia.

While the condition cannot be cured, early diagnosis and treatment can slow or even stop vascular dementia from  worsening.