Forgetting how to do basic arithmetic, swearing in front of your children or suddenly finding yourself unable to remember how to use the printer are all little-known signs of early dementia, a leading expert has warned.

Known as young-onset dementia, the condition has risen by a shocking 69 per cent in the last decade—with more than 70,000 people affected. 

And while symptoms of the disease differ from patient to patient, one expert has told MailOnline of five key signs she often sees in younger patients. 

‘With older patients, forgetting things is often thought of as the first sign of dementia,’ said Professor June Andrews, dementia specialist and author Dementia: The One Step Guide.

‘But the dementia that people get while they’re still working is different in nature.

‘The most pronounced symptom will depend on their lifestyle and responsibilities.

‘It’ll be the sort of thing that you would notice because you can’t cope with daily life the way you used to.’

 So, what are the most common young onset dementia symptoms?

‘With older patients, forgetting things is often thought of as the first sign of dementia,’ says Professor June Andrews (pictured)

Struggling with numbers and swearing more often can be some of the earliest — but too often dismissed — warning signs of young-onset dementia, experts say. Stock image

Struggling with numbers

‘Finding that you’re suddenly having a problem with counting can be an early sign of dementia,’ Prof Andrews said. 

This can look like not being able to remember numbers, or simply hold them in your head while doing mental arithmetic. 

‘If you have to subtract seven from 100, you’ve both got to do the subtraction and remember where you are in the sequence,’ she explained. 

‘It depends a lot on who you are and what you do for work. 

‘For example, a mathematician with young-onset dementia may still be better at maths than his doctor, but have lost some of his mental numeracy.

‘But, just like forgetting words, suddenly being unable to do basic mental maths can be an early sign of the disease.’ 

 Brain fog

 It’s a very common issue for women of a certain age. 

But brain fog isn’t just a symptom of menopause. In fact, it can also be a very common sign of early onset dementia. 

‘In young people, feeling a sense of tiredness, or fogginess, is very common— particularly for parents of young children, or after a late night,’ said Prof Andrews. 

‘So when people of working age find themselves struggling to concentrate in the office, or having difficulties thinking straight, they can easily find a way to explain it away.

‘The problem is, dementia can cause this type of persistent brain fog. 

‘This could look like continually having difficulty understanding instructions or completing assignments, much like when you’re sleep deprived, but all the time.’ 

Around 900,000 Britons are currently thought to have the memory-robbing disorder. But University College London scientists estimate this will rise to 1.7 million within two decades as people live longer. It marks a 40 per cent uptick on the previous forecast in 2017

Sir Terry Pratchett was  hit by a dementia before the age of 65, being diagnosed with a rare type called posterior cortical atrophy (PCA) at 59

Tasks taking longer 

Everyone has slow days. 

But when you consistently find simple tasks are taking you ages, it could be a sign of early onset dementia.

‘Needing more time for things that you used to do easily—or having to look up how to do thinks that were once second nature—is concerning among under-50s,’Prof Andrews explained.

‘I know of one man whose wife began to suspect he was having an affair, because he was coming home later and later from work. 

‘But the truth was sadder. Work that he used to complete easily and quickly was taking him longer and longer to do. 

‘He was having to check manuals for things that could do without even thinking about before.’

But they can also be a sign of dementia — the memory-robbing condition plaguing nearly 1million Brits and 7million Americans

Missing steps in a routine 

There are loads of things that we do almost on autopilot throughout our daily lives, says Professor Andrews. 

But for people with early onset dementia, these steps can get a bit confused.

‘When you’re getting ready for work, there’s a certain order to the steps in which you do things, whether that’s getting out of bed, getting dressed, brushing your teeth or making breakfast,’ she said.

‘If you’re having difficulty with your brain processing, you may start to miss steps out or get them in the wrong order.

‘That’s why sometimes you’ll see people with dementia out on the street in their pajamas. It’s not that they forget but they just have done things in a jumbled way.’

The problem appears in a similar way at work. 

‘At the office, you usually have tasks that need to get done by a certain deadline.

‘But working within a time limit and having to put everything together becomes really hard if you have dementia.’

Swearing more often

Finally, for those with a certain type of dementia that impacts the frontal lobe—the brain’s inhibition regulator—called frontotemporal dementia, a warning sign of the disease can be swearing more than normal. 

‘Most people know when they can and can’t say rude words out loud,’ said Professor Andrews. 

‘But people with dementia that’s affected their frontal lobe increasingly lose the ability to discriminate between what is and isn’t acceptable to say.’

This can be swearing in front of children, or saying inappropriate or rude things to people without realising. 

‘Someone might find themselves increasingly coming out with comments that would previously have left them mortified.’ 

Every person with dementia is different, and presents symptoms differently, Prof Andrews explained. 

‘How quickly you’re diagnosed is a lottery depending on how observant people around you are, and how far you go in terms of denying or concealing the problem,’ she added.