Alzheimer’s disease and vascular dementia are the first and second most common forms of dementia. What sets them apart?
As the proportion of older people in the population around the world increases, the prevalence of dementia will increase in turn. By 2030, it is estimated that 78 million people worldwide will be living with dementia, up from an estimated 50 million people today.Alzheimer’s disease is the most common form of dementia, accounting for 60 to 70 percent of total dementia cases. Vascular dementia is the second most common form, accounting for five to 10 percent of all dementia cases. Vascular dementia is associated with a reduction in blood flow to the brain. People with Alzheimer’s disease will have deposits of toxic amyloid and tau protein plaques in their brain.
Both diseases have similar share risk factors and symptoms, making them sometimes difficult to differentiate. Here are a couple key things to know about vascular dementia.
Some risk factors for Alzheimer’s dementia and vascular dementia overlap; some are distinct.
When it comes to Alzheimer’s, some cases are thought to be caused by things we can’t change, with close links to biological variables such as sex (the disease is far more common in women than in men) and genetics. But other cases are more closely linked to nurture, rather than nature: A recent study identified eight risk factors that are linked to about two of every five Alzheimer’s cases. The most prominent of these risk factors are midlife obesity, physical inactivity, and lower levels of education. Other risk factors include hypertension, depression, diabetes, smoking and hearing loss.
Vascular dementia shares cardiovascular risk factors with Alzheimer’s, including obesity, hypertension and diabetes. People who experience strokes or heart disease are at an elevated risk of vascular dementia.
Vascular dementia also has its risk factors that cannot be controlled — sex and genetics included: Some ethnicities — including Black and Hispanic Americans — have an elevated risk of both cardiovascular disease and vascular dementia. When it comes to sex as a biological variable, the tables are turned: Vascular dementia is more common in men than women.
Symptoms and progression
On average, people with vascular dementia will progress faster than those with Alzheimer’s disease. There is some overlap in the symptoms of each disease, but each has a unique profile.
Alzheimer’s symptoms include:
- Forgetfulness and mild cognitive impairment
- Memory problems
- Difficulty with language, organization, and calculations
- Loss of independence and difficulty doing everyday tasks
- Changes in personality and mood
However, the pathology that signifies Alzheimer’s disease in the brain may begin to form some 10 to 15 years before the disease’s symptoms become outwardly noticeable. Once symptoms surface, the disease progresses quickly, with an average of four to eight years life expectancy after diagnosis, although some people may live significantly longer with Alzheimer’s.
Meanwhile, the symptoms of vascular dementia vary depending on which part of the brain is deprived of blood flow. These symptoms can include:
- Trouble with concentration and communication
- Memory problems
- Symptoms of stroke such as sudden weakness and trouble speaking
- Personality and mood changes
- Problems with balance, walking and gait
Biomarkers and diagnosis
While there are many biomarkers for Alzheimer’s disease, they don’t have perfect track records. Typically, Alzheimer’s disease is diagnosed through a combination of PET brain scans, spinal tap, and cognitive testing. PET brain scans and spinal taps are used to assess the levels of beta-amyloid and tau protein plaques.
Many biotechnology companies are working on developing blood tests for amyloid and tau, which would be less invasive than a spinal tap. However, many of these blood tests are less effective in diagnosing the disease in Black patients.
Further, experts caution that, because Alzheimer’s research has typically included majority white participants, some diagnostic cognitive tests may have less efficacy among different ethnic and racial groups.
New cognitive tests are trying to overcome these limitations by looking for universal biomarkers. Cognetivity’s five-minute test assesses how quickly a person can recognize animals on a tablet screen. Other researchers are looking at the retina, testing whether its thinning is an indicator for early Alzheimer’s disease.
However, there is still a great deal yet to understand about biomarkers in Alzheimer’s, and diagnosis remains challenging.
Unlike Alzheimer’s, vascular dementia isn’t marked by a the buildup of protein plaques in the brain. Rather, it’s diagnosed by looking closely at the way blood moves through the brain.
Vascular dementia can be diagnosed using an MRI scan to identify abnormalities in the brain in conjunction with cognitive assessments. These abnormalities include signs of stroke, thinning blood vessels near the brain and changes in brain connectivity. In addition, some tests will measure blood vessel stiffness and elasticity.
Can you have Alzheimer’s and vascular dementia at the same time?
Most approved treatments for Alzheimer’s disease target cognitive symptoms and memory dysfunction, rather than the underlying pathology.
Aricept, exelon and razadyne are cholinesterase inhibitors which function by preventing the breakdown of the neurotransmitter acetylcholine. Namenda is another drug approved for treating Alzheimer’s cognitive symptoms. Belonging to a class of medications known as NMDA (N-methyl-D-aspartate) receptor antagonists, it blocks the effects of the neurotransmitter glutamate, preventing hyperactivation and cell death.
Aduhelm is the first disease-modifying therapy approved by the FDA for treating early-stage Alzheimer’s, however its efficacy remains unclear. Part of a class of drugs called anti-amyloids, it was designed to target and clear beta-amyloid plaques in the brain There are several other anti-amyloid drug candidates for Alzheimer’s treatment in the clinical trial pipeline now, and a follow-up to Aduhelm could be up for FDA approval as soon as January 2023.
So far, there is no cure or specific treatment for vascular dementia. To potentially slow the rate of its progression, a doctor may prescribe medication to lower blood pressure, reduce cholesterol, prevent blood clotting, and keep blood sugar under control.
The best prevention strategies for both Alzheimer’s and vascular dementia include healthy lifestyle choices with science-backed correlations to lower dementia risk. These include eating a Mediterranean-style diet, getting enough exercise, and managing existing obesity, diabetes and hypertension. Continued learning and socializing are other lifestyle factors that appear to be linked to lower dementia risk in some studies. Meanwhile, new treatments for Alzheimer’s and vascular dementia are in development.