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Alzheimer's disease vs. Dementia - What is the Difference?

Often we hear the terms “Alzheimer’s disease” and “dementia” used interchangeably, which can be confusing. So, what is the difference? Dementia is not a disease, but a general term describing the loss of memory, problem-solving, and other thinking abilities severe enough to interfere with daily life. Alzheimer’s is a brain disease that is one cause of those symptoms of dementia.


Alzheimer’s is a disease of the brain that is characterized by the abnormal buildup of certain proteins between neurons that disrupt cell function. This causes brain cells to eventually die and the brain to shrink. The early signs of the disease typically include forgetting recently learned information, confusion, and difficulty engaging in and following conversations. As the disease progresses, these symptoms become more severe and the person may experience personality and behavioral changes. In the final stage of the disease, the person is unable to respond to their environment, communication is seriously impaired, and there is typically a loss of physical abilities such as walking and swallowing. Round-the-clock care is needed at this stage. Alzheimer’s disease is the leading cause of dementia, representing 60-80% of dementia diagnoses. Although great strides have been made in research, there is currently no cure for Alzheimer’s disease. According to the Alzheimer’s Association’s 2023 Alzheimer's Disease Facts and Figures report , 6.7 million Americans age 65 and older (nearly 11%) have Alzheimer’s Disease. By 2050, that number is expected to more than double. According to the SC Alzheimer's Disease Registry at USC’s Office for the Study of Aging, 111, 818 South Carolina residents were living with Alzheimer’s disease or another form of dementia in 2017.


Although Alzheimer’s disease is the leading cause of dementia, it is certainly not the only cause. The four most common causes of dementia after Alzheimer's disease are:

Vascular dementia is the second most common cause of dementia. It is caused by conditions, such as strokes, that block or reduce blood flow to various parts of the brain. Early symptoms tend to include problems with reasoning, planning, judgment and eventually memory.

Dementia with Lewy bodies  ("DLB") occurs when protein deposits, called Lewy bodies, develop in nerve cells in the brain. Common symptoms in the early stages often include hallucinations, sleep disturbances, frequent, unpredictable swings in cognition as well as movement concerns similar to those in Parkinson’s disease.

Frontotemporal disorders (“FTD”) are caused by the degeneration of the frontal and temporal lobes of the brain. FTD typically strikes at a younger age, the majority of cases occurring between the ages of 45-65. There are three general types: Behavioral Variant FTD involves personality changes, apathy, and a progressive decline in socially appropriate behavior, judgment, self-control, and empathy. Primary Progressive Aphasia is characterized by the gradual loss of the ability to speak, and comprehend what others are saying. Movement disorders involve difficulties with physical movement, shaking, frequent falls and poor coordination.

Mixed Dementia occurs when two causes of dementia are present simultaneously. 

Other diseases that can cause dementia include: 

Posterior Cortical Atrophy 

Huntington's disease

Parkinson's Disease Dementia 

Traumatic Brain Injury

Creutzfeldt-Jakob disease

Korsakoff Syndrome

It is important to understand that none of these forms of dementia are at all a normal part of aging. It is critical to diagnose the correct type of dementia, as early as possible to create an appropriate treatment plan. If you or someone you know suspects or has been diagnosed with Alzheimer’s disease or another dementia, know that you are not alone and that there are resources available to support you, your family members, and caregivers.

Our South Carolina Department on Aging’s website provides a wide variety of support resources, including contact information for the local Area Agency on Aging serving your county.

Find other caregiving services from the South Carolina Department on Aging (SCDOA) or by calling your local Area Agency on Aging.

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