Your Risk Of Alzheimer's Disease If You're Under 50 (And Why Young People Aren't Immune)

When you think of Alzheimer's, an older person probably comes to mind. Perhaps you've had a parent or spouse with Alzheimer's, and their inability to recall recent conversations can be heartbreaking. People with Alzheimer's eventually have difficulty speaking, swallowing, and walking. Most people with Alzheimer's are diagnosed after age 65, a condition known as late-onset Alzheimer's. That doesn't mean younger people can't develop Alzheimer's, however. 

Christopher Norman, a Geriatric Nurse Practitioner with the National Council on Aging, told Health Digest, "It's pretty rare to be diagnosed with Alzheimer's before age 50." However, 5% of people with Alzheimer's are younger than 65. People with early-onset Alzheimer's may show symptoms between the ages of 30 and 60, but it can rarely occur at an even younger age. Norman said a recent case study identified the youngest known Alzheimer's patient at just 19 years old.

A 2023 case study published in the Journal of Alzheimer's Disease highlighted the rare instance of a 19-year-old man who had significant memory decline for two years. Cognitive tests confirmed his memory impairment and brain scans revealed degeneration in areas associated with memory (Here are the most common causes of memory loss). The researchers also found abnormal protein levels in his spinal fluid, similar to those seen in Alzheimer's patients. Despite this, the young man did not carry the genetic mutations typically associated with early-onset Alzheimer's.

Norman said this is an unusual case of early-onset Alzheimer's. "From the published report, no abnormal genes have been discovered in this unfortunate case; there is no known family history and no history of infection or head trauma, making this case a further medical mystery," he said. "The case of this young person should not be considered ordinary by any means."

Even though young people aren't immune from Alzheimer's, Norman adds that cases of early-onset Alzheimer's have remained stable over the last 20 years. "It may seem like it's more common now because better evaluations are available for diagnosing people and people are generally more aware of the disease and its symptoms," he said.

"Early-onset Alzheimer's Disease is strongly linked to genetic factors," said Norman. According to the Mayo Clinic, early-onset Alzheimer's is associated with inherited mutations in the amyloid precursor protein (APP), presenilin 1 (PSEN1), or presenilin 2 (PSEN2) genes. These mutations lead to the buildup of amyloid plaques in the brain, resulting in the death of nerve cells.

Genetic testing for Alzheimer's isn't part of a regular work-up at your doctor's office. You could be recommended for genetic testing if a member of your family has Alzheimer's or if you (or someone you love) begin showing warning signs of Alzheimer's. Although many people will experience some memory decline as they age, Norman says Alzheimer's-related memory problems tend to disrupt daily activities with manifestations such as forgetting events or important dates. People with Alzheimer's may feel disoriented, struggle with simple tasks, and have difficulty following conversations, leading to social withdrawal.

If genetic testing reveals that you carry the APP, PSEN1, or PSEN2 variants, it does not guarantee that you will develop Alzheimer's. According to the National Institute on Aging, 10% to 15% of people with one of these genetic mutations could develop early-onset Alzheimer's. People with Down syndrome are also at a high risk of developing Alzheimer's before the age of 65 due to the presence of an extra chromosome 21, which is linked to the production of amyloid precursor protein.