A dementia expert has revealed how to tell the difference between harmless brain fog and the early signs of Alzheimer's disease.

Figures released by Alzheimer's Research UK stated that 74,261 people died from dementia in 2022, compared with 69,178 a year earlier, making the memory robbing illness -- the most common form of dementia -- the country's biggest killer.

Emma Taylor, an information services manager at Alzheimer's Research UK, told The Sun that there are five key differences between the early stages of the incurable condition and the harmless 'brain fog' which everyone experiences.

She said: 'The biggest difference between brain fog and Alzheimer's is that the brain fog is temporary and often reversible.'

Interestingly, she added that brain fog isn't just a sign of ageing, it can affect people at all stages of life and can be triggered by stress, tiredness and hormonal changes.

Using five specific behaviours, Ms Taylor explained how they are experienced differently by people with Alzheimer's and by people with normal forgetfulness.

These are: being forgetful when you enter a room, misplacing your keys, struggling to say the right word, forgetting appointments, and struggling to follow a conversation.

Firstly, Ms Taylor explained, if you only occasionally walk into the room and forget why you went in then it's likely brain fog -- but if it is a common problem, it could be a sign of Alzheimer's.

A dementia expert has revealed how to tell if your seemingly harmless brain fog is an early sign of Alzheimer's disease

If you have misplaced but eventually manage to find your keys, it's most likely an incident of brain fog -- but if you put them somewhere random like the fridge and don't remember doing it at all, it may be Alzheimer's.

Thirdly, if you struggle to find the right word but it later comes to you it's likely just brain fog.

But, if you're forgetting common words and using totally unrelated ones, that could be a sign to speak to your GP to rule out Alzheimer's.

Similarly, if you forget an appointment but later remember it after being reminded, or it randomly comes to mind, it is probably brain fog.

However, if you forget it entirely, even after being reminded, it could be Alzheimer's.

And finally if you feel mentally sluggish but can still follow a conversation it's likely brain fog -- but if you lose track of what people are saying and repeat questions often it may be Alzheimer's.

If brain fog is causing you concern you should speak to your GP as it can be caused by an underlying illness -- but 'most conditions can be treated or managed with help from a doctor', Ms Taylor told The Sun.

'Brain fog is often used to describe the feeling of not being able to think clearly', Dr Simon Wheeler, senior knowledge officer at Alzheimer's Society also told the outlet.

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'Although it's not a disease or illness itself, it can be a symptom of common conditions including menopause, disorders, chronic pain and chronic fatigue syndrome.'

Meanwhile, he said, if you are worried you or a loved one may have dementia, you can use the Alzheimer's Society's Symptom checklist.

Classic symptoms of dementia include issues with memory, thinking speed, mental sharpness and quickness, language, understanding, judgement and mood.

But there are other lesser-known signs, with studies connecting changes in sight, hearing, touch, balance, and most recently, smell, with early stages of the disease.

Read More New symptom which can predict dementia years before diagnosis

Experts have also warned that problems with spatial awareness -- like standing too close to people -- are also potential early warning signs of dementia.

An early diagnosis for dementia is considered critical, as while the condition is incurable, treatments can combat symptoms and sometimes slow progression.

However, 'if someone is reluctant to seek help, Alzheimer's Research UK has lots of helpful guidance to navigate tricky conversations', added Ms Taylor.

This can include keeping a diary of behaviour changes that you've seen in them to discuss with them.

More than 944,000 people in the UK are thought to be living with dementia, while the figure is thought to be around seven million in the US.

More than half -- an estimated 62 per cent, according to Alzheimer's Research -- of those diagnosed with dementia in the UK are women.

Ms Taylor explained: 'Hormonal changes linked to menopause, specifically a drastic reduction in oestrogen, are part of the reason why women are more likely to develop dementia than men.

'Oestrogen plays a key role in protecting our brain health, so when levels drop, this leaves the brain more vulnerable to Alzheimer's.'

Recent analysis by the Alzheimer's Society estimated the overall annual cost of dementia to the UK is £42billion a year, with families bearing the brunt.

An ageing population means these costs -- which include the lost earnings of unpaid carers -- are set to soar to £90billion in the next 15 years.

Experts shares five differences between brain fog and Alzheimer's