Early Onset Alzheimer's Disease

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MINDY KIM-MILLER, MD, PhD
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Question:

My mother, her mother, and my great aunt had Alzheimers. My mother had early onset and died from the complications at 69. I am now 59. The only sibling. Do I need to take tests? If so what kind? and When? What are the percentages that I will get it? I am a single person and probably do not have the funds for long term care. I get scared when I get forgetful. My biological father was or had manic depression. I have been on Prozac for over 20 years to help with depression and obsessive compulsions.

–Anonymous, 59, Miami Beach

Answer:

Types of Alzheimer’s disease
There are two basic types of Alzheimer’s disease (AD). The more common form, known as late-onset AD, affects people who are usually over the age of 65. This form is thought to be due to both genetic and environmental causes.

The other, less common form is referred to as autosomal dominant, early-onset, or familial AD. This form affects people who are under the age of 65 (typically between 40-60 but can occur as early as 20). Early-onset familial AD not only affects people at an earlier age, but it also is more virulent, causing faster cognitive decline than those with late-onset AD. Early-onset AD is caused by genetic mutations, only some of which have been identified. (The list of these genes and summaries of their relative degrees of genetic association with AD are summarized on the Alzheimer Research Forum at http://www.alzforum.org/res/com/gen/alzgene/default.asp.)
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Early-onset AD accounts for around 4-7% of all AD cases and is inherited in an autosomal dominant manner with high penetrance. This means that if your family truly has a history of early onset AD, you are highly likely to develop it. Early-onset AD requires you to have at least two first-degree relatives with a history of AD. In your case, it is difficult to say whether your family has early-onset AD without examining your family tree more closely and knowing more about your family members’ medical histories.

Diagnosing Alzheimer’s disease
Diagnosing AD can be challenging, because many other diseases and medical conditions can cause similar symptoms. Additionally, it is usually a diagnosis of exclusion, meaning that other possible causes of dementia have to be excluded before the diagnosis of AD can be made with any certainty. Unfortunately there is no simple blood test that directly tests for AD (such blood tests are in development). Currently, there are a series of studies that can help determine whether you have AD. You and your physician(s) have to decide which tests are appropriate for you.

Some of the tests used to evaluate for AD include neuropsychiatric examinations, which test your brain function using verbal, written, and functional tasks. Another type of examination is neuroimaging (taking pictures of the brain), including MRI, CT, PET and SPECT. Anatomic imaging with MRI or CT provides excellent information about brain structure and can show whether you have shrinkage in parts of the brain characteristically seen in AD or other forms of dementia. Functional imaging with PET or SPECT indirectly measures brain activity and can help identify parts of the brain that are not functioning at normal levels. Studies have shown that PET imaging significantly improves the accuracy of diagnosing AD from frontotemporal dementia compared to the usual tests used in diagnosis. Using the combination of anatomic and functional imaging is becoming more common as a powerful tool in the diagnosis of AD and other dementias.

Though not commonly performed, genetic testing is possible to look for some of the mutations that have been identified in association with AD. Genetic testing can be useful for research purposes. However, there is ongoing debate about the ethics and clinical utility of genetic testing. If you think genetic testing might be useful to you, you should consider discussing this with your family members as well as your physician(s) or other healthcare professionals. To learn more about diagnosing AD, you can read the LightBridge article about diagnosing AD and other dementias at http://www.lightbridgehealthcare.com/2129.xml.

People concerned about developing AD usually undergo examination when they develop symptoms. For those with a family history of AD, some tests can be performed prior to symptom onset. Some people do not notice the symptoms until the disease is well-established, while others notice even subtle symptoms. Because of your family history, you may be more vigilant about looking for the symptoms of AD. Your forgetfulness may not be due to AD. I don’t know to what degree you are forgetful, but some forgetfulness is common at any age. Your situation is further complicated by the fact that you have depression; depression and dementia share many common symptoms, including memory issues.

Since you are already near the upper age limit for early-onset AD, you might consider getting tested soon as it might lead to earlier diagnosis. At the least, testing now will provide a baseline for comparison to future tests. Diagnosing the disease earlier in its course allows for earlier intervention, which may slow the progression of the disease. Additionally, testing might give you some peace of mind whether it indicates disease onset or not. Since this is so important to you and will affect your loved ones, you should consider discussing this with those important to you, such as your family, close friends, spiritual leaders, and your physician(s).

I hope this helps. Best of luck to you.

Dr. Mindy Kim-Miller is a trained medical physician who provides useful, but general answers to questions provided by online visitors. While Dr. Mindy can not provide specific medical advice or services, we hope you find her responses useful in your personal education. All information is provided for informational and educational purposes only and is not meant to be a substitute for professional medical advice, diagnosis or treatment. If you suspect you have an illness or disease, or a health related condition of any kind, seek professional medical care with an appropriate health care professional immediately. Do not postpone or delay seeking treatment or disregard professional advice based upon the general answers provided by Dr. Mindy. Dr. Mindy’s advice is not intended to substitute for a visit to your personal physician or other qualified health provider. Any specific medical concerns or questions you may have should be directed to your personal physician or other qualified health provider.

 

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