Big piece of Alzheimer’s puzzle solved

by Madeleine Kolb

Research on Alzheimer’s Disease sometimes seems to proceed one-step-forward-two-steps-back. For example, several recent studies found that so-called Brain Games don’t improve general cognitive function .

Things about Alzheimer’s Disease we know for certain 

  • It destroys memory and the ability to think and reason;
  • It’s irreversible, progressive, and fatal; and
  • The likelihood of being stricken increases dramatically after age 65.

Things about Alzheimer’s Disease we don’t know for certain 

  • What causes it;
  • How to diagnose it;
  • How to prevent it, delay its onset, or slow its progress; and
  • How to treat it.

Diagnosing Alzheimer’s Disease

Ever since it was first described a little over 100 years ago, the only way to know for certain that a person had Alzheimer’s Disease was to wait until he died and perform an autopsy of his brain. 

A pathologist would examine slices of brain tissue under a microscope, looking for tell-tale black freckles, or plaque.  If she saw plaque on the tissue, she would know that the person had had Alzheimer’s Disease. Finding no plaque meant no Alzheimer’s Disease.

So the disease has been diagnosed by a doctor’s examination and tests of cognitive function.

Sample question: List four creatures beginning with the letter “s”, such as “shark.”

Problem with having no accurate test for Alzheimer’s

Even the best of doctors are often wrong. And based on autopsies of  the brains of people with memory loss and cognitive limitations, it turns our that twenty percent of people who were diagnosed as having Alzheimer’s Disease did not have it.

That means that some of the patients diagnosed with Alzheimer’s Disease had other conditions—such as depression, low levels of thyroid hormone, or drug side-effects and interactions—which could have been treated.

New test to scan brains of living persons really works

Recently, an exciting breakthrough was announced. Dr. Daniel Skovronsky and his team had developed a way to detect Alzheimer’s disease in living persons. It involved finding a dye that could get into the brain and stick to plaque and labelling the dye with a radioactive tracer. Then a PET (positron emission tomography) scanner was used to see whether there was plaque in the person’s brain, as shown in the images above.

Next they needed to test the test. Dr. Skovronsky and his team did the necessary test in a hospice with patients in the terminal stages of Alzheimer’s Disease or other conditions. The team performed PET scans on the patients and then, when the patients died, performed brain autopsies. The purpose was to see whether plaque on the PET scans was the same as plaque seen in brain autopsies. 

Preliminary results confirmed that the PET scan and the brain autopsy results were in agreement. Patient whose brains showed plaque while they were alive showed plaque after they died. Those whose brains showed no plaque while they were alive showed no plaque after they died.

The results also indicated that some patients had been properly diagnosed with Alzheimer’s disease while alive, and some had not.

Why this matters so much

***People with memory loss and reduced intellectual function can have a PET scan to determine whether their symptoms are caused by Alzheimer’s Disease or some other condition, and they can be treated accordingly.

***Many drugs to treat Alzheimer’s Disease have been and are being developed. Now their effectiveness can be tested more accurately. After all, how can we know for sure whether medication works for treating Alzheimer’s Disease, if we don’t know for sure that the patient being treated actually has Alzheimer’s Disease?

***This big step forward is likely to bring about more and more steps in the same direction.

Finally, profound thanks is due to the sick and dying patients who agreed to be part of this study. It was too late for their lives to be saved, but, as reported in the NYT article, “…most patients and their families agreed and said they were grateful to have been asked.” I am so touched by that. I welcome your comments.

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{ 2 comments… read them below or add one }

1 Angela Artemis July 14, 2010 at 5:03 pm

Hi Madeleine,
Great post! Alsheimer’s is a mystery for sure. I hope and pray I never get it or anyone dear to me. Thank you for telling us about the new technique to detect the disease. Hopefully early screening and medication can keep it from progressing to quickly.

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2 Madeleine Kolb July 14, 2010 at 6:55 pm

Angela, Thank you. There is so much to learn about Alzheimer’s Disease, but this discovery of a way to diagnose it with certainty is a huge advance.

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