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Genetics and Dementia

In July, Dr Matthew Croucher, a psychiatrist of old age, made himself available to give an overview of dementia and answer questions from the audience. Full, not only of knowledge, but also insight and empathy, the session was of immense value to those who came. It covered an over view of dementia and  its types as well as practical questions about when to do something about any concerns, how to offer encouragement rather than being pushy and telling the truth verses being gentle. Dr Croucher also answered the question about how Alzheimer’s disease related to one another – Dementia is the overriding umbrella and Alzheimer’s disease is one of the main diseases that fits under that umbrella.

One of the questions asked was about whether dementia was hereditary. This is a question of concern not only for a person living with dementia, but also for their children. Dr. Croucher’s answer was, “Genes have less effect than lifestyle or mystery.” The contributing factors that are under your control are more important than those that aren’t under your control.

Our Dementia Canterbury fact sheet about genetics and dementia sites two ways genes can be involved as a contributing factor to a dementia illness:

  • Single gene abnormalities that are so powerful that anyone with the faulty gene is at a very high risk of developing dementia. This is extremely rare.
  • Multiple different genes of small effect combine with environmental factors to increase the risk of dementia. Most diseases that cause dementia fall into this category and they are more weakly inherited.

Therefore, the vast majority of cases of dementia are not strongly inherited. Some rare causes of dementia are strongly inherited, for example dementia caused by Huntington’s disease. This is an “autosomal dominant” disease, which means that every child of someone with the illness has a 50% chance of getting the faulty gene and will go on to get the disease. If you do not inherit the gene, you cannot pass on this condition to your children and you will not get the disease. This is very reassuring news for people living with dementia and their children.

If dementia has occurred in several family members, over two or more generations, in your family and at least one of them had definitely occurred below the age of sixty, you can talk to your GP about considering a referral to a specialist to review the history. They may refer on to the genetics Service at Christchurch Public Hospital. It is very seldom possible to find a single gene culprit and therefore impossible to tell unaffected family members what their risks are, but on very rare occasions specific problems might be found. Sometimes when a family History is very strong it may be possible to bank people’s blood so that future genetic advances might enable better risk assessment.

Anyone who is concerned about their chances of developing dementia as they age should do what we all know is good for our brains: eat healthy food, keep our weight and cholesterol low, keep our blood pressure under control, stop smoking, drink alcohol only in moderation, exercise regularly, keep socially active, and keep your brain active by trying new things.

The Community Education Seminars held at Dementia Canterbury are of great assistance to those who want to learn more about living well with a diagnosis of dementia. Those who attend have the opportunity to glean a great deal from them and they are open to everyone. Please contact Dementia Canterbury on 0800 444 776 for a current Seminar Calendar.


*www.dementiacanterbury.org.nz  ‘Genetics and Dementia.’  Dementia Canterbury resource sheet, October 2017

* Living with dementia.  April 2009.  Alzheimer’s Society UK

* ‘Lewy Body Dementia’.  Headlines, National newsletter of Neurological Foundation of NZ.  Autumn 2009

* ‘The genetics of FTD:  should you worry’. The Association for Frontotemporal Dementias www.ftd-picks.org

* Thanks to Dr Matthew Croucher, Dementia Canterbury Medical Advisor.

About Dementia Canterbury

Dementia Canterbury
Dementia Canterbury offers a free Community Education Programme for 10 months of the year. These sessions are aimed at supporting Care Partners, and other family members of people diagnosed with dementia, by arming them with relevant information and strategies. If you or someone you care about has dementia, it is only natural to feel distressed and concerned. You do not have to face this alone. Getting help, support and advice can make a big difference. Dementia Canterbury provides free information, support and access to services for people with all forms of dementia, their carers, family/whanau. Although there is no cure for most causes of dementia, there is a lot of help available. It is important that you seek help early. Call us on 03 379 2590.