Receiving a dementia diagnosis can be a worrying and frightful time, not just for the person diagnosed but for their family too.
It can raise many questions, some of which we hope we can answer through our blog, written by our Dementia Lead, Chris Sewards.
Is Dementia Hereditary?
One of the main questions I am asked, and possibly one of peoples’ biggest fears, is that dementia runs in the family and that if a parent or grandparent has it, they will develop it too. In most cases, dementia is not inherited (95%), or there is no strong genetic link.
However, research has identified some rare genetic mutations for dementia that are inherited. Every person that has a parent with this gene will have a 50% chance of inheriting these mutations, and of developing dementia in the future. Genetic forms of dementia are more common in people under the age of 65 (known as Young Onset Dementia).
Which dementias can have a genetic link?
Familial Alzheimer’s disease (FAD)
This is a rare form of Alzheimer’s disease that is most common in people with young onset dementia. Only 1% of Alzheimer’s cases have a familial link.
More about Young Onset Dementia here: What is young onset dementia? – Dementia UK
Familial frontotemporal dementia (fFTD)
Around 30-40% cases of frontotemporal dementia (FTD) are genetic. This is known as familial frontotemporal dementia (fFTD). It is most common in people aged 40 to 60. Most FTD is not directly inherited, but about 40 per cent of people who develop the condition will have at least one close relative diagnosed with some kind of dementia. This can include FTD, Alzheimer’s disease or amyotrophic lateral sclerosis (ALS) (sometimes known as motor neurone disease). In general, the greater the number of relatives who have had dementia – particularly FTD or ALS – the greater the chances of developing ‘familial’ FTD.
The most common form of fFTD is behavioural variant frontotemporal dementia (also known as FTD or Pick’s disease). The other type is usually primary progressive aphasia, affecting speech.
More about Frontotemporal Dementia here: Understanding frontotemporal dementia (FTD) – Dementia UK
Vascular dementia
There is a rare form of hereditary vascular dementia but this only affects 1000 people in the UK.
More about vascular dementia here: What is vascular dementia? – Dementia UK
Genetic Testing
Some people who have, or are suspected to have, a genetic form of dementia may wish to have genetic testing. This is a very personal decision, and everyone will have their own reasons for deciding whether or not to proceed.
There are two types of genetic testing:
- Diagnostic genetic testing – for people with a diagnosis of dementia who have a strong pattern of family inheritance. This confirms whether the person’s form of dementia is genetic.
- Predictive genetic testing – to detect genetic mutations in people who have a high risk of familial dementia and assess the chances of them or their children developing dementia.
Genetic tests are not routinely used in clinical settings to diagnose or predict the risk of developing Alzheimer’s or a related dementia. In some cases, if a person has symptoms at an early age with a strong family history of Alzheimer’s, a neurologist or other medical specialist may order a genetic test.
For more advice and guidance relating to dementia, the support available in Salford and how we can help you, please contact Chris Sewards on 0161 607 7100 or email chris.sewards@iamaspire.org.uk
