Dementia VS Alzheimer’s: What is the difference?

In order to understand the difference between Alzheimer’s and Dementia we must first take a look at some contextual words. Alzheimer’s is defined as a “disease” where as dementia is classified as a “syndrome”. So I guess the real question is what’s the difference between a disease and a syndrome.


Webster’s Dictionary defines disease as “a condition of the living animal or plant body or of one of its parts that impairs normal functioning and is typically manifested by distinguishing signs and symptoms.” With that definition I look at the word disease and focus on the part that says it’s typically manifested by distinguishing signs and symptoms diseases usually have a defined cause and process that leads to different forms of treatment and can therefore be diagnosed. Some good examples of diseases are Chicken Pox, Strep Throat, even Athlete’s Foot. There are more technical names for these diseases but they are all identifiable by their signs and symptoms. Because of the define ability of diseases most doctors will give diagnoses in disease form (or name).


One again we will defer to Webster’s Dictionary definition of syndrome as “a group of signs and symptoms that occur together and characterize a particular abnormality or condition” or “a set of concurrent things (such as emotions or actions) that usually form an identifiable pattern”. The Scope conducted an interview with Dr.Kirtly Parker Jones. Dr.Jones is an board certified OBGYN that works for the University of Utah.  According to Dr.Jones “Syndromes are defined by a group of signs or symptoms. And you may not have to have all of them, but you might have two from one group and one from the other to have a syndrome. It is not a disease. Some women with a syndrome aren’t really very ill. And there is no clearly understood process that pulls all the patients together into a group that has a single cause and a defined cure. … Sometimes a syndrome is a bunch of symptoms that we aren’t smart enough yet to understand, and the underlying specific disease process and treatment has not been figured out yet …

 Let’s look at these three examples of syndromes in women. Irritable Bowel Syndrome, more common in women than men and we don’t know why. We don’t know the cause and we’re not really sure of the symptoms. Some women have diarrhea. Some women have constipation. Some have both, and some just have bloating and belly discomfort. But if you have to have some symptoms to run with the Irritable Bowel Syndrome, so you’ve got to have some kind of bowel symptom. We don’t have a good cause and we don’t have a good cure and we don’t have a very good treatment.

Now, the thing about IBS is that there are some diseases that run with the syndrome. Crohn’s Disease, chronic diarrhea from infectious agents like worms or parasites like giardia, and when you have a syndrome you and your clinician need to rule out specific diseases that run with the syndrome, specific diseases with specific causes and specific treatments.

How about Chronic Fatigue Syndrome? Again, more common in women than men. This condition includes a number of debilitating symptoms of fatigue, dizziness, mental confusion, and a number of other symptoms.

Recently, it’s been given a new name that’s confusing to non-clinicians but perhaps better describes the symptoms, myalgic encephelomyelitis. Hear what I mean by it’s confusing? Currently, there are no tests and no specific treatments because, so far, this is a syndrome. However, some women with symptoms of chronic fatigue syndrome have a specific underlying disease. They may have viral encephalitis. They may have underlying bacterial infection. They may even have cancer, and as with other syndromes we have to make sure to rule out specific diseases that have specific causes and treatments.

Now, let’s get to Polycystic Ovary Syndrome. That syndrome is only in women. It’s my favorite or perhaps my least favorite because I’m a reproductive endocrinologist, and I’ve seen this syndrome more than any other. What PCOS is and what it runs with depends on what group of experts are picking the signs and symptoms. Once, a woman had to have all three things — irregular periods, enlarged ovaries with lots of tiny cysts, and evidence of extra male hormones. We didn’t have one disease process that caused these problems, and it was associated with obesity, infertility, increased risk of uterine cancer, diabetes, heart disease.

But many women weren’t obese, infertile, didn’t get cancer, didn’t get heart disease, and didn’t get diabetes. With the older criteria, about 1 in 20 women had this syndrome. The newer criteria were developed suggested women only needed to have two of the following, irregular periods, lots of little cysts which were actually egg cysts, and extra male hormones. Well, just the first two mean that nearly all adolescents could be diagnosed with PCOS, lots of eggs and irregular periods. If teens were given the diagnosis of PCOS, they Googled it and read that they were at risk for obesity, infertility, diabetes, cancer, heart disease, and depression.

And for sure, the last happened because reading all this got them depressed. But a lot of teens grew out of their irregular periods and they didn’t forget their possible diagnoses. So probably if we used the newer criteria, we’ve been over-diagnosing a lot of women with PCOS. With the newer criteria we could possibly make the diagnosis of PCOS in 1 in 5 women instead of 1 in 20. Women with the diagnosis felt overwhelmed, and we didn’t always explain how a syndrome isn’t a disease. It isn’t a death sentence, and some women just seem to get over it. Well, we need to be careful with the diagnosis of syndromes.” 


Thanks to Dr.Jones we can see difference between a disease and a syndrome. Now that we have that understanding we can look at Dementia which is a syndrome. Dementia describes a group of symptoms affecting memory, thinking and social abilities severely enough to interfere with your daily life. It isn’t a specific disease, but several different diseases may cause dementia.

Dementia symptoms vary depending on the cause, but common signs and symptoms include:

  • Cognitive changes
  • Memory loss, which is usually noticed by a spouse or someone else
  • Difficulty communicating or finding words
  • Difficulty with visual and spatial abilities, such as getting lost while driving
  • Difficulty reasoning or problem-solving
  • Difficulty handling complex tasks
  • Difficulty with planning and organizing
  • Difficulty with coordination and motor functions
  • Confusion and disorientation
  • Psychological changes
  • Personality changes
  • Depression
  • Anxiety
  • Inappropriate behavior
  • Paranoia
  • Agitation
  • Hallucinations

There are other diseases that cause the symptoms of Dementia such as Huntington’s disease, Vascular dementia, Lewy body dementia, Parkinson’s, Frontotemporal, Creutzfeldt-Jakob, Wernicke-Korsakoff, Mixed dementia, and Normal pressure hydrocephalus just to name a few. A competent doctor will need to run tests to determine exactly what disease is causing the dementia.

So What’s the life expectancy for someone with dementia?

On average people diagnosed with dementia in their 80’s-90’s will live 4.5 years. People diagnosed with dementia at a younger age have a longer life expectancy, up to 10 years. Even though dementia is terminal and there is no cure every case is different and the type of disease causing the dementia can shorten or lengthen life expectancy. Special care must be given to those with dementia especially as the illness progresses.


 The image above shows the difference between a healthy brain and brain with Alzheimer’s. The defining trait of Alzheimer’s is the development of plaques and tangles. The build up of beta-amyloid lead to plaques while a build up of tau leads to tangles. These 2 protein deposits disrupt communication of nerve cells and branches. It is still being debated weather the disruption of communication is what causes the cell’s death or if the body’s own immune system is causing damage to the healthy cells. Autopsy studies show that most people develop plaques and tangles as they age. However, those with Alzheimer’s develop more plaques and tangles and in a predictable pattern, beginning in the areas important for memory before spreading to other regions.

Either way, Alzheimer’s is a disease. You will often see Alzheimer’s and dementia grouped together because Alzheimer’s falls under the syndrome of Dementia. In fact Alzheimer’s disease is the most common type of dementia. Between 60 and 80 percent of cases of dementia are caused by this disease, according to the Alzheimer’s Association. Early signs of Alzheimer’s disease include depression, forgetting names and recent events, and depressed mood. However, depression is not part of Alzheimer’s disease. It’s a separate disorder that must be treated specifically. Occasionally, depressed older adults are misdiagnosed as having Alzheimer’s disease.

Alzheimer’s disease is characterized by brain cell death. As the disease progresses, people experience confusion and mood changes. They also have trouble speaking and walking. 

Older adults are more likely to develop Alzheimer’s. About 5 percent of cases of Alzheimer’s are early onset Alzheimer’s, occurring in people in their 40’s or 50’s.