Teenager in China becomes youngest person diagnosed with Alzheimer's disease

A teenager in China is the youngest person ever diagnosed with probable Alzheimer's disease, according to a study published on Dec. 31 by the doctors who diagnosed him.

Alzheimer’s is a degenerative disease that affects thinking, memory and behaviour. The overwhelming majority of Alzheimer’s patients are over 65, making this case especially exceptional.

The study, published in the Journal of Alzheimer's Disease, outlines how the unnamed 19-year-old began to show signs of memory loss two years before he was referred to the Innovation Center for Neurological Disorders and Department of Neurology at Xuanwu Hospital, in Beijing.

He'd begun having difficulty concentrating on his high school studies two years earlier, and started to suffer from short-term memory loss one year earlier.

"For example, he could not recall events from just one day prior or the places of his personal belongings," the authors wrote. "He also had difficulty reading and reacting."

Gradually, the teen's memory worsened. The authors wrote he often lost his belongings, couldn't remember whether he had eaten, and struggled to describe content he had just read.

As a result of his worsening condition, he had to withdraw from high school. Before the onset of his symptoms, he'd been considered an above-average student.

A LITANY OF TESTS

Once the teen was referred to Xuanwu Hospital, doctors on his case dove into his medical and family history and ran a litany of tests in the search for clues about his condition.

They found his childhood development had been normal, and neither his parents, grandparents nor close relatives had a history of dementia, cognitive decline or psychiatric illness.

He had no history of head injuries, psychiatric or psychological disorders or diseases related to memory decline, and doctors ruled out other common causes of cognitive impairment in young people, including inflammation, infection, intoxication, abnormal metabolism, trauma, and "congenital abnormalities."

The teen underwent a wide range of neuropsychological tests for mental state, memory, dementia, anxiety and depression, as well as MRI and CT scans, blood and urine and cerebrospinal fluid analysis and a tau tracer to look for tau tangles.

Tau is a protein that supports neurons, or nerve cells, in the brain. The abnormal accumulation of tau, especially in tangles of the protein, is a hallmark of Alzheimer's disease.

His cerebrospinal fluid showed a buildup of abnormal tau and his MRI showed atrophy – the loss of nerve cells and the connections that help them communicate in the brain's tissues – in his hippocampus.

He also scored lower than average on the World Health Organization-University of California Los Angeles Auditory Verbal Learning Test, suggesting he suffered from significantly impaired memory.

Doctors sequenced the teen's genes and those of his family members to look for mutations associated with early-onset Alzheimer's, but found none.

A RARE DIAGNOSIS

Even in the absence of these mutations, they made their diagnosis.

"This is the youngest case ever reported to meet the diagnostic criteria for probable (Alzheimer’s disease) without recognized genetic mutations,” they wrote.

Previously, they explained, the youngest person diagnosed with the disease was 21.

Early-onset Alzheimer’s disease affects people under 65 years old and is rare, accounting for between two and eight per cent, or 28,000, of all known cases in Canada, according to the Alzheimer’s Society of Canada.

The disease can occur sporadically – through a combination of genetics, aging and the environment – or through pathological mutations in genes.

Younger patients tend to carry these gene mutations, as was the case with the previous youngest person diagnosed with Alzheimer's. So specialists were puzzled by the teen's diagnosis and the absence of any mutations. They wrote that his case had altered their "understanding of the typical age of onset of (Alzheimer’s disease.)"

The authors did not say what types of treatment or support their young patient will receive, but said they plan to follow up with him long-term in order to better understand the condition.