A memory clinic in China has diagnosed a 19-year-old with Alzheimer’s disease, making him the youngest person in the world identified with the condition.

Neurologists at Capital Medical University’s Xuanwu Hospital in Beijing say the patient’s brain showed early signs of the neurodegenerative disease, including memory loss, hippocampal atrophy and shrinkage.

After ruling out other causes of cognitive decline, they diagnosed the teen with early onset Alzheimer’s, the most common form of dementia. The research challenges the established view of the disease and its association with aging. It also emphasizes the need for more study in younger people, the authors say.

Alzheimer’s diagnosis climbed 200 per cent between 2013 and 2017 in people aged 30 to 64, with the average age of early onset diagnosis at 49 years old, according to the latest data from Blue Cross Blue Shield. While its prevalence increases with age, about five to six per cent of people diagnosed with the ailment develop characteristic symptoms before the age of 65, according to Mayo Clinic.

The teen’s memory decline started with an inability to focus in class about two years before the consultation with the clinic, the study says. As his cognitive ability deteriorated, he had trouble reading, remembering events from the day before and would misplace his belongings.

The adolescent, being unable to finish homework, could not remember whether he had eaten or even react to things fast enough, and had to drop out of high school. The results of an auditory and learning test further confirmed a memory disorder, placing him far behind his peers in short- and long-term memory recall.

A sample of the young patient’s cerebrospinal fluid had a high concentration of p-tau181, while a PET scan showed mild hippocampal atrophy, the study says. Both indicators led the authors to diagnose him with “probable” Alzheimer’s disease.

Strangely, though, a whole genome sequence showed no inherited gene mutations for the condition, which younger patients typically have.

The patient also has no family with a history of the disease or any head trauma or disease that could explain his diminished cognitive ability. The perplexing and rare case was recently published in the Journal of Alzheimer’s Disease.

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