What is young-onset Alzheimer’s and how are its symptoms different?

Alzheimer’s disease is often thought of as a condition that only affects the elderly. But around 3.9 million people worldwide aged 30-64 live with young-onset Alzheimer’s disease – a form of dementia in which symptoms appear before the age of 65.

English journalist and broadcaster Fiona Phillips, 62, recently revealed that she’d been diagnosed with it. In the interview, Phillips shared that the main symptoms she had experienced before her diagnosis were brain fog and anxiety – highlighting just how different young-onset can be from late-onset Alzheimer’s disease.

First, symptoms begin much earlier – as young as 30 in some rare cases, though it’s typically diagnosed between the ages of 50-64.

While people with Alzheimer’s disease commonly experience memory loss as the first sign of the disease, people with young-onset Alzheimer’s tend to have other symptoms – such as worse attention, less ability to mimic hand gestures and worse spatial awareness.

Some people with young-onset Alzheimer’s may also experience an increase in anxiety prior to their diagnosis. This may be due to an awareness of the changes occurring, without a clear reason as to why they’re feeling different.

They may think these changes in behaviour are temporary, which can put people off seeking medical help. Healthcare professionals may also misinterpret anxiety as a sign of other health conditions.

But while they may have less cognitive impairment at the time of diagnosis, studies have indicated that those living with young-onset Alzheimer’s disease show more rapid changes in their brain. This indicates that the condition can be more aggressive than late-onset Alzheimer’s disease. This may also explain why people with early-onset Alzheimer’s tend to have a life expectancy around two years shorter than those with late-onset.

Research shows that people with young-onset Alzheimer’s are also more aware of the changes in their brain activity. This can lead to behavioural changes – with conditions such as depression being prevalent in this group.

Within the brain itself, young-onset Alzheimer’s disease causes similar chemical changes as those in late-onset Alzheimer’s. But the brain areas targeted by these chemical changes can be different.

Research has found that brain areas involved in processing sensory- and movement-related information (called the parietal cortex) show greater signs of damage. There is also less damage to the hippocampus compared to late-onset Alzheimer’s – an area of the brain important in learning and memory.

Why it happens

The risk factors for young-onset Alzheimer’s disease are similar to those for late-onset Alzheimer’s.

For example, poor levels of cardiovascular fitness and lower cognitive ability in early adulthood have been linked to an eight-fold increased risk of developing young-onset Alzheimer’s. However, we are yet to fully understand all the factors that influence a person’s chances of developing the condition.

One aspect experts are clear on is that genetics play a role in about one in ten cases of young-onset Alzheimer’s disease. So far, three genes (APP, PSEN1 and PSEN2) have been linked to young onset Alzheimer’s disease.

These genes are all related to a toxic protein that is thought to contribute to Alzheimer’s disease (known as amyloid beta). When these genes become faulty, there’s an accumulation of toxic amyloid beta, which is linked to symptoms of Alzheimer’s disease.

Growing evidence suggests there may also be a link between traumatic brain injury and young-onset Alzheimer’s disease.

What can people do

In the UK, people diagnosed with young-onset Alzheimer’s disease can be prescribed medication which can help manage symptoms.

But in the US, two therapies have been approved which may slow the progression of symptoms. However, these were only tested on people with late-onset Alzheimer’s disease, so it’s uncertain if they will have as distinct of an effect.

People who may have a family history of dementia or are concerned about their risk can have a genetic test done through a private company. This will confirm the presence of the faulty genes. These tests can be carried out for those showing symptoms, or those with a family history that wish to know their future prognosis.

While it’s not possible to modify genetics if you are at greater risk, some research does support the idea that you can strengthen your resilience against the disease through a healthier lifestyle. One study found that when people who were genetically predisposed to early onset Alzheimer’s exercised for more than two-and-a-half hours per week, they scored better in memory tests than those who weren’t as physically active.

Alongside being more active, diet choices may also lower risk of young-onset Alzheimer’s. An Italian study found that people who consumed high levels of vegetables, dry fruits and chocolate appeared to have lower risk.

Mark Dallas is Associate Professor in Cellular Neuroscience, University of Reading.

This article was first published on The Conversation.