Most Alzheimer's disease patients get it after the age of 65 although it can strike anyone at any age, as per Alzheimer's Society. Those who were diagnosed before 65 have an early-onset Alzheimer's disease, which is a kind of young-onset dementia, like the 19-year-old man from China.

Neurologists at Xuanwu hospital in China report in their paper "A 19-Year-Old Adolescent with Probable Alzheimer's Disease," which was published in the Journal of Alzheimer's Disease, that they discovered the world's youngest Alzheimer's disease patient and described his case in their report.

Youngest Alzheimer's Disease Patient Is a 19-Year-old Teenager in China; What Is the Average Age of Such a Diagnosis?
(Photo : Unsplash/National Cancer Institute)
A computer-assisted tomographic (CAT) scanner, with a Caucasian female technician working at a screen and behind a glass wall. A patient is on a table and being tested by the CAT scanner.

World's Youngest Alzheimer's Disease Patient

The male teenager has been suffering from memory decline since he was 17 years old, Science Alert reported. He had a hard time even with reading as his short-term memory is declining. Oftentimes, he cannot even remember events that happened a day before and was always misplacing things.

As his condition worsened, he was referred to a memory clinic. His full-scale memory score at that time was 82% lower than his peers his own age while his immediate memory was 87% lower.

Meanwhile, imaging of his brain showed shrinkage in the hippocampus, a part of the brain responsible for memory; and his cerebrospinal fluid showed markers of dementia.

Neurologist Jianping Jia and colleagues wrote in their report that the patient had a very early onset of Alzheimer's disease with no clear pathogenic gene mutation, which suggests that its pathogenesis still needs to be investigated.

Nonetheless, his case shows that Alzheimer's disease does not follow a single pathway and is much more complex than previously thought. It emerges through different avenues with varying effects. The neurologists told the South China Morning Post in an interview that future studies should focus on early-onset cases to further improve understanding of memory loss.

They predict that exploring the mysteries of cases of young people with Alzheimer's disease may become one of the most challenging scientific questions of the future.

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Early Onset Alzheimer's Without Gene Mutation

It is often thought that only old people could be diagnosed with Alzheimer's disease. However, some young people may also experience it and they actually account for up to 10% of all diagnoses.

As Science Alert reported, almost all patients under 30 with Alzheimer's disease could be explained by pathological gene mutations that put them under the familial Alzheimer's disease (FAD) category. The younger the person who receives the diagnosis, the more likely it is due to a gene they have inherited.

However, that is not the case with the 19-year-old man from China. Researchers at the Capital Medical University, which is affiliated with the Xuanwu hospital, could not find any of the usual mutations responsible for the patient's early onset of memory loss, nor any suspect genes when they performed a genome-wide search.

Prior to this case, the youngest Alzheimer's disease patient was a 21-year-old who carried the PSEN1 gene mutation, which causes abnormal proteins to build up in the brain and form clumps of toxic plaques.

Cases like this are still a mystery, especially because the 19-year-old's family does not have any history of Alzheimer's disease or dementia, making it more difficult to categorize as FAD. There were also no other diseases, infections, or head trauma to explain his sudden cognitive decline.

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