One of the main risks of developing dementia is age and dementia usually affects people over the age of 65, however some people develop dementia much younger, known as young-onset dementia.
Young-onset dementia, also known as early-onset dementia or working age dementia, refers to people whose symptoms start before the age of 65. In cases where the symptoms start after the age of 65, it is known as late-onset dementia.
More people and organisations prefer to use the term young-onset or working age dementia to early-onset dementia to avoid confusion with the early stages of dementia generally.
Although the diseases that cause late on-set dementia are largely the same as young-onset dementia, there are some differences:
- Young-onset dementia is much more likely, than late-onset dementia, to be hereditary.
- People with young-onset dementia are much more likely to have a rarer form of dementia (around 20 – 25%).
- Young-onset dementia is also more likely to cause problems with movement, walking, co-ordination or balance.
Types of young-onset dementia
Young-onset Alzheimer’s disease
Young-onset Alzheimer’s disease is rare and accounts for up to 5% of all cases (with half of these as a result of familial Alzheimer’s disease, see below). Non-familial young-onset Alzheimer’s can develop in people who are in their thirties or forties, but that is extremely rare, with the majority of people in their fifties or early sixties.
Familial Alzheimer’s disease
Familial Alzheimer’s disease is an inherited disease passed down by a faulty gene from an affected parent. Familial Alzheimer’s disease usually develops between 50 and 65 years of age, but can be as early as 15. Familial Alzheimer’s disease accounts for approximately half the cases of young-onset Alzheimer’s disease
Vascular dementia is caused by reduced blood flow to the brain, often as a result of a stroke or a series of small strokes and is thought to account for 15%-20% of cases of dementia in the under 65s.
In addition there is a rare form of vascular dementia caused by faulty genes, known as CADSIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy). CADSIL can be passed down through families and is most common in people aged 30 to 50.
Although Frontotemporal dementia is one of the less common forms of dementia, it is a significant cause of dementia in younger people. Frontotemporal dementia is most often diagnosed between the ages of 45 and 65.
In around a third of people it can be triggered by a genetic problem known as ‘familial FTD’.
Dementia with Lewy bodies
About 5 – 10 per cent of younger people with dementia may have dementia with Lewy bodies.
Also known as alcohol related brain damage, Korsakoff’s syndrome is caused by a lack of vitamin B1 (thiamine), often as a result of alcoholism. Korsakoff’s syndrome accounts for around 10% of dementia in younger people.
Around 20 to 25 per cent of younger people with dementia are thought to have a rarer cause of the condition including:
- Progressive supranuclear palsy (PSP) mainly affects people over the age of 60, although it occasionally affects younger people.
- Corticobasal degeneration (CBD) mostly develops in adults aged between 50 and 70.
- Creutzfeldt-Jakob disease (CJD). There are 4 main types of CJD including an inherited version. The age of onset depends on the type but typically affects younger people.
- Niemann-Pick disease type C is one of a group of rare inherited disorders that mainly affects school-age children but can occur at any time, from early infancy to adulthood.
- Huntington’s disease which is typically inherited from a person’s parents and usually appears in a person’s 30s or 40’s but more rarely appears in adolescence.
The most common cause of young-onset dementia
The breakdown of which disease causes the most cases of early-onset dementia is roughly as follows:
- Alzheimer’s disease is the most common accounting for between 30% – 35% of cases of dementia in people under 65. Approx half of these cases are as a result of familial Alzheimer’s disease.
- Vascular dementia accounts for 15% – 20% of cases.
- Frontotemporal dementia accounts for 10% – 15% of cases, with around a third triggered by a genetic problem known as ‘familial FTD’.
- Dementia with Lewy bodies accounts for 5% – 10% of cases.
- Korsakoff’s syndrome accounts for around 10% of dementia in younger people.
- Around 20 to 25 per cent of younger people with dementia are thought to have a rarer cause of the condition.
This article covers the basic facts and figures relating to young-set dementia but doesn’t address the particular challenges faced by younger people following a diagnosis of dementia. For more help and advice download the Alzheimer’s Societies booklet which contains lots of useful information and available support.