What Is Dementia?

What Causes Dementia?

Dementia is the result of changes in certain brain regions that cause neurons (nerve cells) and their connections to stop working properly. Researchers have connected changes in the brain to certain forms of dementia, but, in most cases, the underlying causes are unknown. For a small number of people, rare genetic variants that cause dementia have been identified.

Although some people may be diagnosed simply as having “dementia,” to best tailor treatment and prepare for the future, it is ideal to know the specific type.

Types of dementia include:

• Alzheimer’s disease, the most common dementia diagnosis among older adults. Alzheimer’s dementia is typically associated with abnormal buildups of proteins in the brain — known as amyloid plaques and tau tangles — along with a loss of connection among nerve cells. These changes can be seen during life using a PET scan.
• Frontotemporal dementia (FTD), which is rare and tends to occur in people younger than 60. FTD is named for the areas of the brain affected. Changes in the frontal lobe lead to behavioral symptoms, whereas changes in the temporal lobe lead to problems with language and emotions. These changes include abnormal amounts or forms of the proteins tau and TDP-43, and the loss of nerve cells.
• Lewy body dementia (LBD), with symptoms that include problems with thinking, movement, behavior, and mood. People with LBD have abnormal deposits of a protein called alpha-synuclein in the brain, also called Lewy bodies.
• Vascular dementia, a diagnosis of dementia in people who have vascular changes in the brain, such as a stroke or injury to small vessels carrying blood to the brain. People diagnosed with a vascular dementia may also show changes in the brain’s white matter, i.e., the connecting "wires" of the brain that relay messages between regions. These changes can be seen with an MRI.
• Mixed dementia, which refers to a diagnosis of dementia that is thought to be connected to a mixture of changes in the brain. For example, a person might have evidence of changes traditionally associated with both Alzheimer’s and vascular dementia. Researchers are continuing to explore how and why multiple distinct dementia-related brain changes can develop at the same time. This will help them better understand these various disorders and develop personalized prevention and treatment strategies.

Together, the conditions are often referred to as Alzheimer’s disease and Alzheimer’s disease-related dementias because they share many features and may commonly occur together.

Scientists are investigating how the underlying disease processes in different forms of dementia start and influence each other. They also continue to explore the variety of disorders and disease processes that contribute to dementia, including previously unidentified causes. For example, researchers recently characterized a brain disorder involving the TDP-43 protein called limbic predominant age-related TDP-43 encephalopathy, or LATE. LATE causes symptoms similar to Alzheimer’s, including memory loss, but has different underlying causes. Researchers identified LATE based on results of autopsy studies that revealed build-ups of the protein TDP-43. Recent research suggests that LATE can contribute to cognitive decline alone or in combination with other types of dementia and that people over the age of 80 are at the greatest risk. LATE can currently only be diagnosed after death through an autopsy. Researchers are working to further explore the causes of and risk factors for LATE and to identify ways that could help doctors diagnose and treat it.

Many other conditions can cause dementia or dementia-like symptoms, including Creutzfeldt-Jakob disease, Huntington's disease, chronic traumatic encephalopathy, and HIV-associated dementia. In addition, certain medical conditions — and even some medications — can cause serious memory problems like those seen in dementia. Scientists continue to research disorders that cause dementia or similar symptoms.

What Are the Signs and Symptoms of Dementia?

Many people associate dementia with memory loss. This is because memory problems are often one of the early symptoms of a dementia disorder, but they are not the only one. The symptoms of dementia can vary, depending on the type of dementia and which areas of the brain are affected. Symptoms may include:

• Memory loss, poor judgment, and confusion
• Changes in the ability to speak, understand, and express thoughts and/or words and to write and read
• Wandering and getting lost in a familiar neighborhood
• Trouble handling money and paying bills
• Repeating questions
• Using unusual words to refer to familiar objects
• Taking longer to complete normal daily tasks
• Loss of interest in normal daily activities or events
• Hallucinations, delusions, and paranoia
• Acting impulsively
• Not caring about other people’s feelings
• Problems with balance and movement

People with dementia and those caring for them can face great challenges, including the person’s ability to handle tasks, changes in family relationships, loss of work, and the need for more care as the underlying disease progresses. People in the earlier stages of dementia may need help with daily activities, while people with advanced dementia may need constant care and supervision.

People with intellectual and developmental disabilities can also develop dementia as they age. Recognizing the symptoms can be difficult because they may be attributed to the person's disability. It’s important to consider a person’s existing ability and watch for changes over time that may signal dementia.

How Is Dementia Diagnosed and Treated?

To diagnose dementia, a doctor will complete a medical history, physical exam, and neurological tests that assess balance, sensory response, reflexes, and memory and thinking skills. In addition, a doctor may order brain scans, blood tests, genetic tests, a spinal tap, and a mental health evaluation to help determine a diagnosis.

Because different types of dementia can share similar symptoms, providing an accurate diagnosis can be difficult. In addition, dementia may be difficult to diagnose as a single disease given that a person could have more than one type.

Visiting a primary care doctor is often the first step for people who are experiencing symptoms of dementia. Your doctor may refer you to a neurologist, which is a specialist in disorders of the brain and nervous system. Neurologists generally have the expertise needed to diagnose dementia.

While there is currently no cure for Alzheimer’s or related dementias, medicines are emerging to treat disease progression. There are also medications that may temporarily improve or stabilize memory and thinking skills in some people and may help manage certain symptoms and behavioral problems. A team of specialists — doctors, nurses, and therapists — can help with maintaining mobility; addressing speech and swallowing problems; and learning new ways to handle loss of skills with everyday tasks, such as feeding oneself.

Through substantial investments from the U.S. federal government and others, researchers continue to advance scientific growth and discovery to improve the diagnosis, treatment, and care of those living with dementia.

What Can You Do?

If you are concerned about memory problems or other symptoms of dementia, call your doctor. If you or someone you know has recently been diagnosed, explore the resources on this website and referenced below to find out more about dementia care, support, and research. It is important to educate family, friends, and caregivers about a loved one’s diagnosis. In-person and online support groups offered by nonprofit organizations can provide families and caregivers with additional resources and opportunities to share experiences and express concerns. You may also consider participating in a clinical trial or study.