Everyone experiences occasional episodes of forgetfulness. Many people fear that a growing number of such lapses is a sure sign of dementia. But there are important differences between simple forgetfulness and dementia.


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What is dementia?

Dementia is a catchall term that covers memory loss, confusion, changes in personality, a decline in thinking skills, and a dwindling ability to perform everyday activities. Dementia interferes with a person’s ability to function at home, socially, or at work.

There are many types of dementia. Alzheimer's disease is the most common. In fact, Alzheimer’s disease accounts for 60% to 80% of all dementia cases. Alzheimer's is caused by the accumulation of tangles and clumps of protein in and around brain cells (neurons). These tangles and clumps make it difficult for brain cells to communicate with one another and the brain cells die.

Other types of dementia include:

Vascular dementia. The second most common type of dementia—vascular dementia—develops when cholesterol-clogged blood vessels can't deliver enough oxygen to the brain. Small blockages deprive some brain cells of oxygen, which causes a series of small strokes that kills them.

Dementia with Lewy bodies. Lewy bodies are abnormal clumps of proteins inside brain cells that interfere with the functioning of neurons and damage the neurotransmitters that the brain cells use to communicate.

Frontotemporal dementia. Damage to the nerve cells in the frontal or temporal lobes of the brain leads to problems with personality and behavior as well as trouble with language and motor functions.

Mixed dementia. This involves brain changes that result from more than one type of dementia, such as Alzheimer’s plus vascular dementia.

The science behind what causes dementia, and who is most at risk, is evolving. Advanced age is a common risk factor. Dementia can also be hereditary. Having a first-degree relative like a parent or sibling with dementia raises the risk. 

Certain health conditions are associated with a higher risk of dementia, such as diabetes, obesity, and heart disease.

A small percentage of people with dementia develop the condition because of underlying medical issues such as an underactive thyroid gland, infection, insufficient vitamin B12, medication side effects, or drinking too much alcohol. In these cases, treating the underlying cause can reverse the dementia.

What are the symptoms of dementia?

Symptoms of dementia emerge slowly, worsen over time, and limit the person's ability to function.

The first symptom (and often the earliest sign) of dementia is memory loss. Everyone has memory lapses from time to time. However, memory loss with dementia is more profound and affects the ability to function. 

For example, forgetting where you put your car key is normal. Forgetting how to use the key is a possible sign of dementia. Often, someone with dementia does not realize they have a problem. Instead, family or friends recognize something is wrong.

A person with dementia will likely have trouble with complex mental tasks, such as balancing a checkbook, driving, and retaining new information. They may be inattentive and display poor judgment. Their mood and behavior also may change.

As the disorder progresses, the person will have difficulty speaking in complete sentences. They may not recognize their surroundings or people they know. Problems with personal care, like bathing, are common. Sometimes, a person with dementia may experience hallucinations and delusions. They may get easily agitated and withdrawn.

How is dementia diagnosed?

A diagnosis of dementia requires a doctor visit. He or she will ask when memory problems began and how quickly they worsened. It can be helpful for someone to accompany the individual being examined. That person should be familiar with the patient’s medical history, current symptoms, and concerns. 

Such information and the person's age can suggest a likely diagnosis. However, determining the exact cause of dementia in any individual will require additional evaluation.

To further help with a diagnosis, the doctor will monitor the patient’s memory to watch for further decline, along with at least one of the following:

  • Difficulty understanding or using language
  • The inability to perform a purposeful act or sequence of motor activities
  • The failure to recognize familiar objects or people
  • Difficulty with planning or organizing tasks

Doctors also conduct various tests, including neuropsychological tests and functional assessments, as part of the diagnostic process. A commonly used tool is the Mini Mental State Exam, which tests a person's memory and attention. It consists of 11 short assessments, such as asking the person what day and year it is or having them count backward from 100 by sevens (100, 93, 86, etc.). If the person answers correctly, dementia is less likely.

Laboratory tests can help with diagnosis and narrow down the possible causes. These include:

Magnetic resonance imaging (MRI) or computed tomography (CT) scans. These imaging tests of the head and brain can reveal tumors and signs of stroke. 

Positron emission tomography (PET) scans. These scans can measure the build-up of abnormal amyloid protein in the brain, one of the hallmarks of Alzheimer's. 

Blood tests. These help determine if vitamin B12 deficiency or low levels of thyroid hormone may be contributing to decreased mental functioning.

What is Lewy Body dementia?

Another type of dementia is dementia with Lewy bodies. Lewy bodies are abnormal clumps of proteins inside brain cells (neurons). These clumps interfere with the functioning of neurons and damage the neurotransmitters neurons use to communicate. Some neurons eventually die. (Lewy bodies are also found in people with degenerative neurologic conditions like Parkinson’s disease.)

Lewy bodies can cause widespread injury to the brain, but they mainly affect certain regions. In dementia with Lewy bodies, Lewy bodies arise first in the cerebral cortex, the brain region responsible for thinking, attention, visual processing, and other higher mental functions. Common symptoms include problems with attention, alertness, judgment, memory, and hallucinations. 

After a year or two, people usually develop movement issues and other physical symptoms similar to those seen in Parkinson’s disease, such as slow walking, balance issues, and difficulty initiating movements.

Other symptoms that may arise include constipation, bladder dysfunction, lightheadedness upon standing, and REM sleep behavior disorder, in which people act out their vivid dreams by talking, kicking, punching, or walking in their sleep.

The exact cause of dementia with Lewy bodies is unknown, and currently there is no cure. Treatments are designed to help manage symptoms and can include medication for behavioral problems and physical and occupational therapy to help with movement difficulties.

What are the stages of dementia?

The different types of dementia — Alzheimer’s disease, vascular dementia, dementia with Lewy bodies, frontotemporal dementia, and mixed dementia — each has its own predominant symptoms and stages of progression.

Memory loss is the most common symptom of all dementia types. This may lead to changes in abstract thinking, reasoning and judgment, language, or visuospatial abilities. 

Along with memory loss, a person with dementia will have trouble with complex mental tasks, such as managing finances or simple personal care, such as bathing.

Eventually, mood, behavior, and personality changes, such as apathy, anxiety, depression, irritability, agitation, hallucinations, delusions, loss of empathy, sleep, or changes in appetite arise. 

In the final stages, the person may have difficulty speaking in complete sentences. They may not recognize their surroundings or once-familiar people. 

What are treatments for dementia? Are there medications for dementia?

Once dementia develops, it is almost impossible to reverse. The goal of treatment is to manage symptoms and slow their progression.


Medications for mild to moderate Alzheimer's (the most common type of dementia) may offer modest, temporary help with cognitive function, mental decline, and behavior problems. 

These drugs are sometimes used to treat behavioral symptoms related to dementia with Lewy bodies. 

Other approaches

People with vascular dementia, caused by damaged blood flow to the brain, may show less mental decline if they:

  • Control their blood pressure 
  • Stop smoking
  • Lower their levels of LDL ("bad") cholesterol
  • Exercise regularly
  • Maintain a healthy weight

A small percentage of people with dementia develop the condition because of medical issues, such as an underactive thyroid gland, an infection, vitamin B12 deficiency, medication side effects, or drinking too much alcohol. Treating these conditions may improve the dementia.

Physical and occupational therapy may improve movement and balance. Psychotherapy techniques like reality orientation and memory retraining can also help people with dementia. Music, art, and occupational therapy can provide stimulation and improve muscle control.

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