The Genetics of Memory Loss
In the movie Finding Nemo, the lovable Dori explains to Marlin that she suffers from short term memory loss. She says that it "runs in the family." This short clip highlights both the humor and the frustration that short term memory loss causes.
As we watched, my son commented, "That must be what it's like for you when you're at work, Mom." I laughed, "Sometimes it IS like that, Coby." He asked, "Mom, does Dori have dementia?"
Is she right? Does memory loss run in families? Is he right? Does Dori have dementia? Considering the overwhelming number of people that have dementia, or are projected to be diagnosed with dementia, these are commonly asked questions.
Many people with dementia are concerned that they have inherited the disease and that they may pass it on to their children. Simultaneously, family members and children of people with memory impairment are worried they might be more likely to develop dementia themselves. We can better understand the heredity of memory loss by looking at our genetics.
The characteristics we have inherited from our parents are passed down to us in the form genes- thousands of them. They are found in every cell in our body and provide instructions needed to build our bodies.
While many of our genes are exactly the same, some genes have small variations that yield the physical differences between people. These variations can also be the cause of diseases. Some of these variations among genes are common. They are call genetic variants. In other instances, the variations are rare and are called mutations.
While genes are important building blocks, most of our physical characteristics and the diseases we experience are also greatly influenced by our environment and lifestyle. These factors, alone or in combination, can modify the effects of our genetic inheritance for dementia like Alzheimer's.
Alzheimer's is the most common form of dementia and is the best understood. It is considered to have two basic forms: early onset and late onset. These two types of Alzheimer's disease generally have two patterns of genetic inheritance.
Early onset Alzheimer's Disease
- A rare form of the disease where first symptoms begin to appear before the age of 65.
- This form of Alzheimer's tends to cluster within families, sometimes with several generations affected. It is considered a familial disease.
- In some cases, the younger onset of Alzheimer's is caused by a genetic mutation. It is extremely rare.
- People with any of these mutations tend to develop Alzheimer's disease in their 30s and 40s.
- It is likely that all of those who inherit the faulty versions of these genes will develop dementia.
- Approximately half of the children of a person with one of these rare genetic mutations will inherit the disease.
Late Onset Alzheimer's Disease
- The most common form of the disease where diagnosis occurs after the age of 65.
- Having a relative with this form of Alzheimer's increases your chances of developing it, but not in a predictable way.
- Genetic variations act to increase or decrease the risk of developing Alzheimer's but are not related to its direct cause.
- Those who have a parent, brother, sister or child with dementia are more likely to develop the disease. The risk increases if more than one family member has the illness.
- For someone with a close relative who is diagnosed later in life, the risk of developing Alzheimer's is doubled. It is not inevitable.
- Anyone can reduce their risk of developing dementia by adopting a healthy lifestyle.
Most experts believe that the majority of Alzheimer's Disease (and its related memory loss) occurs as a result of complicated interactions between genes and other risk factors. So, in most cases, our risk of developing dementia is determined by a complex mix of our age, lifestyle and whether we carry any of those risk genes.
Now, back to the original questions: Does memory loss run in families? Yes, it does. Does Dori have dementia? It sounds like early onset Alzheimer's to me.
Please share this information with someone you know who can benefit, and, if you can remember, check of her newest movie, Finding Dori.
Just keep swimming.
Dori, Finding Nemo