Dementia Types

Bitterroot Neurology
Stuart Kieran, MD
1019 West Main Street
Hamilton, MT 59840
(406) 375-9310

Dementia Types
I am often asked, "What the difference between dementia and Alzheimer's?" First we must define dementia. It is a decline in cognitive (thinking) abilities. Some of these abilities were discussed last week and include short term memory, long term memory, working memory, visual and spatial recognition, abstract thinking, logic and creative abilities. While there are different criteria for defining this decline, basically when 2 or more abilities decrease significantly and there is a functional decline in daily life, then this is a dementia. Notice that a person with developmental delay since birth or early childhood does not have dementia as this is not a decline but a static and long standing condition.

When this decline is suspected it is important to decide what is causing it before it can be treated. Alzheimer's is one of the causes of dementia but what causes this is still actively being researched. Other causes of dementia include, strokes, certain vitamin deficiencies, hydrocephalus, (which is excess fluid inside the brain) thyroid abnormalities, Huntington's disease, chronic alcoholism, multiple concussions and many more. The most common is Alzheimer's and stroke (in the broadest sense of the term), meaning vascular disease and its manifestations. So basically, Alzheimer's disease is one type of dementia.

Interestingly, there seems to be some overlap in the risk factors causing the dementia from vascular disease, often called vascular dementia, and Alzheimer's. These include diabetes, smoking, hypertension and obesity. It is sometimes asked by researchers if Alzheimer's disease is a form of vascular dementia. This has implications for prevention and treatment of both conditions. A simple way of thinking about this is - what is good for the heart is good for the brain. This will be discussed in a future article.

Is Alzheimer's inherited? While the risk of getting Alzheimer's is slightly increased if someone had a first degree relative with it, it is not dramatically increased unless the relative had the onset of Alzheimer's at a very early age, such as in their 40's. This is rare but does occur. The incidence of Alzheimer's is low in the 40's and 50's but increases significantly every decade to where it is up to 50 percent of people in their 90's. With the aging of the population, this has become a major socioeconomic factor in most Western countries. It has been calculated that even if the onset of Alzheimer's can be delayed by 5 years, we would save hundreds of billions of dollars a year in health care costs.

Is there a test for Alzheimer's disease and should someone have it if this is suspected? A doctor will often do a CT or MRI scan of the brain, some blood tests and occasionally a brain wave test (EEG) if dementia of any sort is suspected. This is not to specifically diagnose Alzheimer's but rather to look for other treatable or reversible causes for dementia. There are, however, a number of specific tests that can assess the chances of a dementia being Alzheimer's disease perse. These include blood tests of various types (and expense), spinal fluid testing which requires a lumbar puncture and radiographic tests which are only done in research centers. While these tests can increase the probability of knowing if someone has Alzheimer's, they are still not 100% so one is still left with some uncertainty. Also, it often does not change things in a practical way in terms of medications, life style changes, or other plans. This is again different if one had a relative with young onset Alzheimer's and family planning is being considered.

A topic of current discussion, debate, research and legal issues is that of concussions. Multiple concussions can lead to cognitive decline, mood and memory changes, and what has come to be called Chronic Traumatic Encephalopathy (CTE). While CTE is not equivalent to dementia, it can lead to it and has a number of features in common with it. One only has to tune into the news and can quickly see the debates going on with the NFL, colleges and even down to high school and middle school levels, about how to protect students and professionals engaged in football and other contact sports. We are learning more as health professionals and as a society on how to handle those at risk. There are so many issues involved that it is beyond the scope of this article but it is something to be aware of as it will affect many people's lives and livelihood.

Next week we will discuss prevention and available treatments for dementia.

The community health column is brought to you this month by a partnership between Marcus Daly Memorial Hospital and Bitterroot Neurology. For questions and or comments, please contact Stuart Kieran, MD at Bitterroot Neurology, 1019 West Main Street Hamilton, MT 59840 or call (406) 375-9310. Working together to build a healthier community!


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