What's the Difference Between Alzheimer's and Dementia?

Posted: 6/19/2018 12:11 PM by Interim HealthCare

The terms are often used interchangeably, but they’re not the same.

By Kathleen Doheny
If you’re not quite sure of the difference between dementia and Alzheimer’s disease, you’re not alone. Some people use the terms interchangeably. Others insist that their loved one has one but not the other.
The difference is actually pretty simple: Dementia is a group of symptoms relating to memory problems and cognitive decline. It’s not a specific disease, explains James Hendrix, PhD, director of global science initiatives for the Alzheimer's Association.
"Saying someone has dementia is like saying they have a fever," he says. "You have to understand what is causing the dementia.” The most common cause of dementia is Alzheimer's disease, but many other conditions can cause dementia symptoms.
"Often physicians will prefer to use the term ‘dementia’ because that is what they see," Hendrix says. They don't want to call it Alzheimer's disease or any other specific condition until they know the cause of the symptoms. (The only definitive way to diagnose Alzheimer’s disease is through an autopsy after death, but doctors can conduct tests to assess symptoms and rule out other possible causes.)
Causes of dementia include:   
  • Alzheimer’s disease. Alzheimer's occurs when nerve cells in the brain are damaged or destroyed. Abnormal structures known as plaques (deposits of sticky protein fragments called beta-amyloid that accumulate in the space between the nerve cells) and tangles (twisted fibers of a protein called tau that build up inside brain cells) develop, and they might be the cause of the damage. The damage affects thinking, learning and remembering. Alzheimer’s disease can also cause disorientation and mood and behavior changes.
  • Vascular dementia. After Alzheimer's disease, the most common cause of dementia is blocked or reduced blood flow to parts of the brain, often caused by a stroke. Signs and symptoms of vascular dementia typically come on suddenly and progress in clear stages. They can include aggression, hallucinations, paranoia and fluctuating mood. People with high blood pressure, diabetes or high cholesterol are more likely to develop this.
  • Lewy body dementia. The third most common cause of dementia is thought to occur when the brain has trouble processing a protein, alpha-synuclein, that is widely present. Deposits of the protein form; they are known as Lewy bodies. Visual hallucinations and delusions, along with confusion and loss of thinking skills, are common. Problems with normal movement can also happen.
  • Frontotemporal dementia. In this group of conditions (there are several subtypes), the frontal lobe of the brain (located behind the forehead) and the temporal lobe (located behind the ears) shrink over time, with ongoing nerve cell loss. It often begins before age 65, and sometimes even in the 20s. About a third of these cases are inherited. Problems with the brain protein tau and another protein known as TDP43 are suspected causes. Different subtypes cause different symptoms.
  • Parkinson's dementia. Experts believe the same problems with the brain protein involved in Lewy body dementia are at play in Parkinson's dementia. Eventually, most people with Parkinson’s disease will develop Parkinson's dementia. It can involve hallucinations and mood changes, including apathy.
  • Creutzfeldt-Jakob disease. This is a rare and rapidly fatal brain disorder in which spongy holes form in the brain tissue. The cause appears to be abnormal, infectious versions of a type of protein called a prion. It typically begins at around age 60. In addition to memory and cognitive problems and mood changes, it can cause lack of coordination, visual disturbances and involuntary movements.
Some of the symptoms of these conditions overlap. It’s important to identify the cause of the dementia in order to create the right treatment plan — and so that the person with dementia and their loved ones know what to expect and can plan accordingly.   
Scientists are learning more each day about the various causes of dementia. Each one is complex, but research is progressing. Gaining a better understanding of the factors at play should lead to improvements in treatment — and could also reveal clues to prevention.
Kathleen Doheny is a Los Angeles-based journalist who specializes in health, behavior and fitness reporting.