Other Types of Dementia Differ from Alzheimer's Disease

Dorian Martin Health Guide
  • This is a good time to be alive if you’re worried about developing dementia. That’s because -- thanks to technology -- researchers have the ability to actually see what’s going on in the brain and tease apart the mysteries of dementia. And it turns out that not all of them are Alzheimer’s disease!

    There are four types of dementias include:

    • Tauopathies – Diseases that are part of this type are caused when tau proteins clump together inside the brain’s nerve cells, thus causing them to stop functioning. Other dementias in this category include Alzheimer’s disease and frontotemporal disorders.
    • Synucleinopathies – A protein called alpha-synuclein accumulates inside the brain’s neurons in these disorders. Dementias in this category include dementia with Lewy bodies and Parkinson’s disease dementia.
    • Vascular dementia and vascular cognitive impairment are caused by injuries to blood vessels in the brain due to multiple strokes or any injury to small blood vessels. Types of vascular dementia include multi-infarct dementia and subcortical vascular dementia.
    • Mixed dementias, which involve having multiple types of dementia at the same time. The National Institute on Aging pointed to one study that found that 40 percent of people who were believed to have Alzheimer’s disease had some form of cerebrovascular disease.  

    Recently researchers have identified another new form of dementia, primary age-related tauopathy (PART). While PART closely resembles Alzheimer’s disease in the type of impairment that people experience, this disease does not result in the development of amyloid plaques, which are the hallmark of Alzheimer’s disease. Researchers previously thought that people who had tau tangles but not plaques in their brains were in the very earliest stages of Alzheimer’s disease or had a variant in which the tangles were present to harder to detect. It turns out that hypothesis was not correct.

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    Researchers from the United States, Canada, Europe and Japan now have identified criteria for the diagnosis of this new brain disease. “Until now, PART has been difficult to treat or even study because of lack of well-defined criteria,” said Dr. Peter T. Nelson, the study’s co-leader who is from the University of Kentucky’s Sanders-Brown Center on Aging. “Now that the scientific community has come to a consensus on what the key features of PART are, this will help doctors diagnose different forms of memory impairment early. These advancements will have a big impact on our ability to recognize and develop effective treatments for brain diseases seen in older persons.”

    Researchers have found that people with PART have tangles that are seen primarily in areas of the brain related to memory. They also believe that PART actually may be fairly prevalent since diagnostic tests show that as many as 25 percent of people who have been diagnosed with mild cognitive impairment have tau but no amyloid plaque in their brains. Furthermore, this condition is often mild in individuals who are considered younger elderly, but becomes more severe when people reach at an advanced age.

  • This information is really important as researchers look for treatments for dementia. For instance, many people with undiagnosed PART may have been involved in clinical trials for the development of drugs that target amyloid plaque. These drugs wouldn’t be effective since these people don’t have these plaques. Thus, researchers now have to focus on developing medications that can fight PART and also screen out people with PART from participating in trials focused on Alzheimer’s disease.

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    The difference between PART and Alzheimer’s disease offers an illustration of why it’s important to have the doctor determine exactly which type of dementia a loved one has. Some disorders like Alzheimer’s disease cause a progressive and irreversible loss of brain function. However, other types of dementia actually can be stopped or reversed with treatment. Therefore, it’s important to identify exactly which brain condition the loved one is facing and then get appropriate treatments.

    Primary Sources for This Sharepost:

    National Institutes of Health. (2014). The dementias: Hope through research.

    University of Kentucky College of Medicine. (2014). New Alzheimer’s-related memory disorder identified.

Published On: November 18, 2014