Experts pinpoint typical life expectancy from initial dementia diagnosis - and there's a huge variation between different subtypes

A patient's life expectancy after being diagnosed with early onset dementia depends on the subtype of the disease, new research suggests—and it varies hugely.

The memory-robbing condition is the UK's biggest killer, and it is estimated that nearly a million people are currently living with the disease and the figure expected to soar by over 40 per cent by 2040.

Dementia is an umbrella term for several types of the condition; the most common variation is Alzheimer's disease, which affects up to 70 per cent of cases, as well as vascular, Lewy body, and frontotemporal.

A new study published in the Journal of Neurology, Neurosurgery & Psychiatry has pinpointed the typical survival times for early-onset dementia, which is when the diagnosis of the disease comes before the age of 65.

Scientists from the University of Eastern Finland's Institute of Clinical Medicine reviewed and reassessed all 12,490 visits made to dementia outpatient clinics in two university hospital districts in Finland between 2010 and 2021.

They identified 794 confirmed cases of early-onset dementia, of whom 215 died during the study.

The data revealed that the average life expectancy of the most common type of early-onset dementia, Alzheimer's Disease, was nearly 10 years.

The shortest survival time, for people diagnosed with frontotemporal dementia and Lewy body dementia, was nearly seven years.

However, people with a diagnosis of both frontotemporal dementia and motor neurone disease lived on average for just two years after diagnosis.

The scientists compared information about each study cohort member with 10 people of a similar age, sex and geographical region—but who didn't have a degenerative brain disease—sourced from a population database of 8,000.

When those with early-onset dementia of any type were compared to people without any neurodegenerative illness, death rate (from any cause, not just dementia) was on average 6.5 times higher.

People diagnosed with frontotemporal dementia were 14 times more likely to die, and people with vascular cognitive impairment were four times more likely.

Diabetes was found to be linked to a reduced survival time in those with early-onset dementia.

Being male, of an older age, having co-existing conditions, and lower educational attainment are all linked to an increased risk of death - but the researchers noted no direct correlation between these factors and developing early-onset dementia.

If dementia is caught early on, it allows patients to have personalised treatments which can slow the progression of the illness.

In the journal, the researchers wrote that they hoped that their findings would help inform the treatment and care provision of those diagnosed with early onset dementia.

They wrote: 'Accurate up-to-date data on the survival and mortality rates of [early-onset dementia] are crucial in designing healthcare structures, comprehensive patient care, and clinical trials.'

It comes amid a worrying rise in the number of people in the UK being diagnosed with early-onset dementia.

Figures published by the charity Dementia UK in 2022 revealed it affects 70,800 Britons - which has risen by 69 per cent rise since 2014.

Early signs of dementia include forgetfulness, losing belongings, struggling to think of the right word, asking questions repetitively and hesitance to try new things.

However, recent studies have shown that loss of smell, sight, hearing, taste, touch and balance are also signs of the illness.

Risk factors for dementia include family history, head injuries heart disease, smoking, obesity, diabetes, high blood pressure and high cholesterol.