Dementia usually develops in people ages 65 and older. So-called early-onset dementia, which occurs in those younger than 65, is rare. A new study published in JAMA Neurology in December 2023 has identified 15 factors associated with a higher risk of early-onset dementia.
Let’s look at what they found and—most importantly—what you can do to reduce your own risks.
Are early dementia and early-onset dementia the same thing?
No. Experts consider early dementia to be the first stage of dementia. Mild cognitive impairment and mild dementia are forms of early dementia. So someone could have early dementia at age 50, 65, or 88.
Early-onset dementia refers to the age at which dementia is diagnosed. A person has early-onset dementia if symptoms and diagnosis occur before age 65.
What has research shown so far?
A previous study of men in Sweden identified some risk factors for early-onset dementia, including high blood pressure, stroke, depression, alcohol abuse, vitamin D deficiency, substance abuse and general cognitive function.
What you should know about the new study
In the new study, a research team in the Netherlands and the United Kingdom looked at data from the UK Biobank. The biobank tracks about half a million people in the United Kingdom who were between 37 and 73 years old when they joined the project between 2006 and 2010. Most participants identified as white (89%), and the remaining 11% were described only as “other.” Just over half of the participants (54%) were women.
The researchers excluded anyone aged 65 or over and anyone who already had dementia at the start of the study, leaving 356,052 participants for the analyses. Over the course of about a decade, 485 participants developed early-onset dementia. The researchers compared participants who developed early-onset dementia and those who did not to identify possible risk factors.
What did the researchers find about the risks for early childhood dementia?
When reviewing the results, I think it’s helpful to group the risk factors into several categories and then examine each one. These risks can affect the brain directly or indirectly.
Eight factors we know or strongly suspect cause dementia:
Genes: Carrying two apolipoprotein E (APOE) ε4 alleles is a major genetic risk factor for Alzheimer’s disease. The risk is thought to be caused by the APOE ε4 protein not efficiently removing amyloid from the brain. This allows amyloid to build up and form plaques, starting the cascade to cell death and Alzheimer’s disease.
A diagnosis of alcohol use disorder (AUD) is associated with damage to several parts of the brain, including the frontal lobes, leading to problems with executive function and working memory. Combined with poor nutrition, AUD also damages small regions connected to the hippocampus that are critical for forming new memories.
Social isolation is a major risk factor for dementia. Although the exact mechanism is unknown, it may be because our brains largely evolved for social interactions. Individuals with fewer social contacts have fewer social interactions and simply don’t use their brains enough to stay healthy.
Not getting enough vitamin D can lead to more viral infections. Several studies suggest that certain viral infections increase the risk of dementia.
Poor hearing increases the risk of dementia, as I explained in a previous post. This is likely due to reduced brain stimulation and reduced social interactions. Using hearing aids reduces this risk.
Having a previous stroke is a risk factor because strokes directly damage the brain, which can lead to vascular dementia.
Having heart disease is a major risk factor for strokes, which in turn can lead to vascular dementia.
If you’re a man, diabetes can lead to dementia in many different ways. Why only if you’re a man? Researchers suspect this is because middle-aged men are more likely than women to suffer from diabetes-related mini-strokes, which in turn can lead to vascular dementia.
Two Factors That Reduce Cognitive Reserve
Cognitive reserve can be described as our ability to think, improvise and solve problems, even as our brains change with age. These two risk factors make dementia symptoms more likely to appear at a younger age.
Less formal education may affect your familiarity with the questions on the pen-and-paper cognitive tests used to diagnose dementia.
Lower socioeconomic status may be related to poorer quality of education.
Is every factor identified in the study a clear risk?
No, for the following reasons: Sometimes research reveals obvious risk factors that could be due to reverse causality. For example, it is possible that symptoms of impending dementia appear to be risk factors because they become apparent before obvious dementia is diagnosed.
Lower handgrip strength is a sign of frailty, which is often associated with dementia.
Not drinking alcohol is a risk factor because people may stop drinking if they develop memory loss (also known as the “healthy drinker effect” in dementia).
Depression is a risk factor because many people become sad when they can’t remember or fear dementia.
And finally, there are risk factors that can be either a contributing cause or a consequence of impending dementia.
High C-reactive protein levels are a sign of inflammation.
Orthostatic hypotension is an abnormal drop in blood pressure when a person stands up after lying or sitting. This condition can lead to brain damage and dementia, but it can also be a consequence of some types of dementia, such as Parkinson’s dementia and Lewy body dementia.
What can you do to prevent early-onset dementia?
Here are five steps you can take to lower your risk of developing dementia before age 65:
Don’t drink too much alcohol.
Look for opportunities to socialize with others regularly.
Make sure you get enough vitamin D. You can produce your own vitamin D when your skin is exposed to sunlight (without sunscreen), but in northern climates you may need to take a supplement, especially in the winter. Because vitamin D can interact with other medications, ask your doctor about this option.
Make sure you have good hearing and use a hearing aid if you don’t.
Exercise regularly, eat a healthy diet, maintain a healthy weight, and work with your doctor to lower your risk of stroke, heart disease, and diabetes.