But what if the person is not in their 80s but in their 30s, 40s or 50s and forgets the way home from their own street corner? That’s far more concerning. While most of the 5.3 million Americans who are living with Alzheimer’s disease or other forms of dementia are over 65, some 200,000 are younger than 65 and develop serious memory and thinking problems far earlier in life than expected.
“Young-onset dementia is a particularly disheartening diagnosis because it affects individuals in the prime years,” Dr David S Knopman, a neurologist at the Mayo Clinic in Rochester, Minnesota, wrote in a July 2021 editorial in JAMA Neurology. Many of the afflicted are in their 40s and 50s, midcareer, hardly ready to retire and perhaps still raising a family.
Dementia in a younger adult is especially traumatic and challenging for families to acknowledge, and many practicing physicians fail to recognise it or even suspect it may be an underlying cause of symptoms.
“Complaints about brain fog in young patients are very common and are mostly benign,” Knopman told me. “It’s hard to know when they’re not attributable to stress, depression or anxiety or the result of normal aging. Even neurologists infrequently see patients with young-onset dementia.”
Yet recent studies indicate that the problem is far more common than most doctors realise. Worldwide, as many as 3.9 million people younger than 65 may be affected, a Dutch analysis of 74 studies indicated. The study, published in JAMA Neurology in September, found that for every 100,000 people ages 30 to 64, 119 had early dementia.
The accompanying editorial by Knopman called young-onset dementia “an underappreciated problem.” Its diagnosis, he wrote, is often delayed, and knowledge about its management is “in short supply as well.”
The various causes of early-onset dementia
The Dutch study found that overall, Alzheimer’s disease was the most common cause of young-onset dementia. But when symptoms developed before age 50, early-onset Alzheimer’s was a less likely explanation than two other causes: vascular dementia and frontotemporal dementia.
Vascular dementia results from a blockage or injury to blood vessels in the brain that interfere with circulation and deprive the brain of oxygen and nutrients. Its most common symptoms, in addition to memory problems, are confusion, difficulty concentrating, trouble organizing thoughts or tasks, and slowed thinking.
In frontotemporal dementia, portions of the brain that lie behind the forehead and ears shrink, resulting in dramatic personality changes, socially inappropriate or impulsive behavior and emotional indifference. Movement and memory problems typically develop later in the course of the disease. According to the Mayo Clinic, frontotemporal dementia often begins between the ages of 40 and 65 and may be misdiagnosed as a psychiatric problem.
Lewy body disease is another cause of dementia in younger adults. It is associated with abnormal deposits of a protein called alpha-synuclein in the brain that affects brain chemistry and leads to behavioral, thought and movement problems. Most of the symptoms are similar to those seen in other dementias, and additional symptoms like hallucinations may resemble schizophrenia, but the decline in brain function occurs significantly faster. A distinguishing symptom of Lewy body dementia is having violent dreams and attempting to act them out, Knopman said.
Alzheimer’s disease remains the most common cause of dementia in younger as well as older adults. There is an inherited form of Alzheimer’s that typically arises at younger ages, but those cases account for fewer than 10 percent of young-onset disease. Most cases of Alzheimer’s occur sporadically, for unknown reasons, though genetic factors may increase risk.
People with Alzheimer’s typically have a buildup of abnormal substances — tau and beta-amyloid proteins — in the brain. Early symptoms include impaired memory, language problems, difficulty concentrating and finishing tasks, poor judgment and visual or spatial deficits that result in problems like driving errors and getting lost. Brain scans may show a loss of brain cells and an impaired ability to metabolize glucose that is indicative of degenerative brain disease.
Probably the most publicized factor known to increase the risk of early dementia is repeated head injuries like those experienced by professional boxers, football and soccer players, and sometimes by military veterans.
Once brain cells are injured or lost, there’s no going back. So preventing head injuries is the best possible protection at the moment.
Many parents these days try to discourage youngsters from playing sports like football, in which repeated head injuries are common. However, proper and consistent use of helmets and not heading the ball in soccer can limit their risk of head injuries. Knopman said he’s less concerned with elementary school children playing such sports; the risk of developing dementia at a young age from repeated head trauma is much greater among those who played Division 1 football or became professional boxers.
Among older adults in general, the same inflammatory factors associated with atherosclerosis, the clogging and hardening of the arteries that nourish the heart, can also afflict blood vessels that feed the brain. Body-wide inflammation linked to diabetes and heart disease can cause brain changes that promote dementia.
Diagnosis of early-onset dementia
Accurately diagnosing young-onset dementia can be difficult and time-consuming and should start with a detailed medical history, Knopman said. “If doctors don’t ask the right questions, families may fail to mention a telltale symptom like violent dreams.”
A thorough cognitive assessment of the person’s memory and language difficulties is critical, he said. Does the person stumble over words or say “white” when he means “black”? Neuropsychological tests can detect subtle difficulties with memory, visual, cognitive and executive functions.
A brain scan is needed to rule out the possibility that a tumor is causing the person’s cognitive symptoms. A spinal tap and analysis of the spinal fluid can reveal elevated levels of tau and beta-amyloid proteins in the brain. An MRI scan can depict shrinkage in specific parts of the brain. And a glucose PET scan can uncover abnormal patterns of sugar uptake in various parts of the brain that can help distinguish between Alzheimer’s disease, Lewy body dementia and frontotemporal dementia. “Different degenerative brain diseases have specific patterns of glucose uptake,” Knopman said.
As with older dementia patients, it’s essential to keep young people with dementia safe. They should no longer drive, operate dangerous equipment, including the stove, or be left alone. All should wear an identifying tag day and night that alerts others to their condition.
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