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The Difference Between Alzheimer's And Dementia

Dementia is a syndrome, a group of symptoms that occur together; Alzheimer’s is a disease, a disorder that produces dementia symptoms.

While dementia is an umbrella term describing a set of memory and cognitive decline symptoms, many different conditions lead to these symptoms. A thorough examination that includes a mental evaluation, blood and urine testing and imaging tests such as CT scans, MRIs and PET scans can help determine the cause of dementia. 

Alzheimer’s is the leading cause of dementia, accounting for 50 to 80 percent of cases, but it’s not the only one. There are more than 70 different causes of dementia and every individual responds uniquely to these causes. 

Distinguishing among various dementia causes can be difficult, given that many symptoms overlap. Some forms have distinct features.

A patient who has Lewy body dementia, for example, has the Lewy body disease and shows general symptoms of cognitive decline. Distinguishing features – a walking impairment, visual hallucinations and fluctuations in cognitive function – point to Lewy body as the cause or type of dementia, and shape the individual’s treatment plan.

Initial dementia symptoms vary, depending on the cause. In advanced stages of dementia, the differences among causes become subtler as patients lose the ability to perform everyday tasks. 

Alzheimer’s disease, however, doesn’t have a “single behavioral marker that can reliably discriminate AD from the other dementias,” according to the Center of Excellence on Brain Aging and Department of Neurology in New York.

Alzheimer’s symptoms include:

  • Memory loss
  • Problems with planning or problem solving
  • Losing track of time
  • Having vision problems
  • Misplacing things
  • Poor decision making
  • Problems with speaking or writing
  • Changes in mood and personality 

These symptoms are very similar to general dementia symptoms. Testing can eliminate other causes, but Alzheimer’s disease can’t be diagnosed with 100 percent accuracy until after an individual dies and a neuropathologist performs an autopsy.

Often, Alzheimer’s disease occurs concurrently with another pathology such as Lewy bodies or vascular dementia. An atypical case of Alzheimer’s disease can be wrongly presumed to be some other disease.

Although Alzheimer’s disease is difficult to diagnose, the difference between this particular disorder and dementia is clear: Alzheimer’s disease causes dementia symptoms, making it one of many forms of dementia.  


Dementia is a decline of mental abilities such as thinking, reasoning, and memory. Dementia usually occurs in older age; it is rare under the age of 60. It is serious enough to diminish everday life.