If you’re in your 80s or 70s and you’ve noticed that you’re having some memory loss, it might be reasonable to be concerned that you could be developing Alzheimer’s disease or another form of dementia. But what if you’re in your 60s, 50s, or 40s… surely those ages would be too young for Alzheimer’s disease or dementia, right?
About 10% of Alzheimer’s disease is young-onset, starting before age 65
Not necessarily. Of the more than 55 million people living with dementia worldwide, approximately 60% to 70% of them have Alzheimer’s disease. And of those 33 to 38.5 million people with Alzheimer’s disease, memory loss or other symptoms began before age 65 in 10% of them. Alzheimer’s is, in fact, the most common cause of young-onset dementia. A recent study from the Netherlands found that of those with a known classification of their young onset dementia, 55% had Alzheimer’s disease, 11% vascular dementia, 3% frontotemporal dementia, 3% Parkinson’s disease dementia, 2% dementia with Lewy bodies, and 2% primary progressive aphasia.
Young-onset dementia is uncommon
To be clear, young-onset dementia (by definition starting prior to age 65, and sometimes called early-onset dementia) is uncommon. One study in Norway found that young-onset dementia occurred in 163 out of every 100,000 individuals; that’s less than 0.5% of the population. So, if you’re younger than 65 and you’ve noticed some trouble with your memory, you have a 99.5% chance of there being a cause other than dementia. (Whew!)
There are a few exceptions to this statement. Because they have an extra copy of the chromosome that carries the gene for the amyloid found in Alzheimer’s plaques, more than half of people with Down syndrome develop Alzheimer’s disease, typically in their 40s and 50s. Other genetic abnormalities that run in families can also cause Alzheimer’s disease to start in people’s 50s, 40s, or even 30s — but you would know if you are at risk because one of your parents would have had young-onset Alzheimer’s disease.
How does young-onset Alzheimer’s disease differ from late-onset disease?
The first thing that should be clearly stated is that, just as no two people are the same, no two individuals with Alzheimer’s disease show the same symptoms, even if the disease started at the same age. Nevertheless, there are some differences between young-onset and late-onset Alzheimer’s disease.
People with typical, late-onset Alzheimer’s disease starting at age 65 or older show the combination of changes in thinking and memory due to Alzheimer’s disease plus those changes that are part of normal aging. The parts of the brain that change the most in normal aging are the frontal lobes. The frontal lobes are responsible for many different cognitive functions, including working memory — the ability to keep information in one’s head and manipulate it — and insight into the problems that one is having.
This means that, in relation to cognitive function, people with young-onset Alzheimer’s disease may show relatively isolated problems with their episodic memory — the ability to form new memories to remember the recent episodes of their lives. People with late-onset Alzheimer’s disease show problems with episodic memory, working memory, and insight. So, you would imagine that life is tougher for those with late-onset Alzheimer’s disease, right?
Depression and anxiety are more common in young-onset Alzheimer’s disease
People with late-onset Alzheimer’s disease do show more impairment, on average, in their cognition and daily function than those with young-onset Alzheimer’s disease, at least when the disease starts. However, because their insight is also impaired, those with the late-onset disease don’t notice these difficulties that much. Most of my patients with late-onset Alzheimer’s disease will tell me either that their memory problems are quite mild, or that they don’t have any memory problems at all!
Introducing the First-Ever Harvard Health Annual
Tap the expertise of top Harvard doctors in every area of medicine…all in one place. Cutting-edge health research, breakthroughs, insights—even answers to your most pressing questions inside.
Bible verses for today’s meditation and inspiration: Matthew E. McLaren
Rejoice always, pray continually, give thanks in all circumstances; for this is God’s will for you in Christ Jesus. 1 Thessalonians 5:16-18 NIV
The Lord your God is with you, the Mighty Warrior who saves. He will take great delight in you; in his love he will no longer rebuke you, but will rejoice over you with singing. Zephaniah 3:17
Rejoice in the Lord always. I will say it again: Rejoice! Philippians 4:4 NIV
Be joyful in hope, patient in affliction, faithful in prayer. Romans 12:12 NIV
When anxiety was great within me, your consolation brought me joy. Psalm 94:19 NIV
The Lord has done it this very day; let us rejoice today and be glad. Psalm 118:24 NIV
Though the fig tree does not bud and there are no grapes on the vines, though the olive crop fails and the fields produce no food, though there are no sheep in the pen and no cattle in the stalls, yet I will rejoice in the Lord, I will be joyful in God my Savior. Habakkuk 3:17-18 NIV
You make known to me the path of life; you will fill me with joy in your presence, with eternal pleasures at your right hand. Psalm 16:11 NIV
Though you have not seen him, you love him; and even though you do not see him now, you believe in him and are filled with an inexpressible and glorious joy, for you are receiving the end result of your faith, the salvation of your souls. 1 Peter 1:8-9 NIV
Recommended contacts for prayer requests and Bible study