Alzheimer’s disease is known to affect the elderly, and one would never expect a teenage individual to develop the neurodegenerative condition. However, this extremely rare case happened in China, and the researchers are yet to understand its underlying cause.
In 2023, a Chinese memory clinic diagnosed a 19-year-old with Alzheimer’s disease, making him the world’s youngest-ever Alzheimer’s patient. The teenage boy started experiencing memory issues at 17 and with time his cognitive health deteriorated, so much so that he couldn’t even complete his high school.
The brain of the young patient was found to have shrinkage in the hippocampus involved with memory, and his cerebrospinal fluid hinted at common signs of dementia.
What made this case puzzling and unique to Capital Medical University in Beijing researchers was that the patient didn’t have a gene mutation that could put his case in the case of familial Alzheimer’s disease (FAD), which may happen in case of early onset disease. The teenager also didn’t have any other disease, infection, or head trauma that could explain his sudden cognitive decline. The case was detailed in the Journal of Alzheimer’s Disease.
How the memory decline began?
The teenager started facing trouble focusing in his class two years before his diagnosis. Not only he found reading difficult but also faced decline in short-term memory. He also couldn’t remember events from the day before, and often misplaced his belongings. The young man unfortunately couldn’t complete his high school, though he could still live independently.
The cause remains a mystery
According to WHO, Alzheimer disease is the most common form of dementia and may contribute to 60–70% of cases.
Around 10% cases of Alzheimer’s disease are early onset but all the patients who are under 30 years of age can have their Alzheimer’s explained by pathological gene mutations. This puts them into the category of familial Alzheimer’s disease (FAD). In the case of young people, the likely cause is a faulty gene. In this particular case, however, the researchers couldn’t find any such mutation or gene.
“The patient had very early-onset AD with no clear pathogenic mutations,” neurologist Jianping Jia and colleagues wrote in their study, “which suggests that its pathogenesis still needs to be explored.””Exploring the mysteries of young people with Alzheimer’s disease may become one of the most challenging scientific questions of the future,” they said.
Causes of young-onset dementia
The causes of young-onset dementia are similar to the diseases that leads to dementia in older people. In case of young, as per Alzheimer’s Society, frontotemporal dementia (FTD), is more common. Dementia in younger people also has different symptoms than those reported in older people.
Familial Alzheimer
Familial Alzheimer’s disease is an extremely rare form of Alzheimer’s caused by inherited genetic mutations. It involves changes in three specific genes — PSEN1, PSEN2, and APP — and carries a 50% chance of being passed from parent to child. People with this condition often have a strong family history of Alzheimer’s, with symptoms typically appearing in their 30s, 40s, or 50s. The earlier the onset, the more likely the disease is linked to genetics. Overall, familial Alzheimer’s accounts for fewer than 1% of all Alzheimer’s cases.
Atypical Alzheimer’s disease
Younger people diagnosed with Alzheimer’s disease are more likely to have an atypical form, where the symptoms differ from the typical memory loss seen in older adults. In posterior cortical atrophy (PCA), early signs involve problems processing visual information, such as difficulty reading or judging distances. In logopenic aphasia, language difficulties appear first, with individuals struggling to find the right words or pausing frequently during speech. Meanwhile, behavioural/dysexecutive Alzheimer’s disease tends to start with problems in planning, decision-making, and socially inappropriate behaviour.