Medically Reviewed by Zilpah Sheikh, MD on April 15, 2024
13 min read

Dementia (also called major neurocognitive disorder) isn’t a disease. It's a group of symptoms caused by other conditions. Dementia is a broad term for loss of thinking ability that is severe enough to interfere with your daily life. Thinking abilities include things such as memory, language skills, problem-solving, visual perception, self-management, and your ability to focus and pay attention.

About 5%-8% of adults over age 65 have some form of dementia. This percentage doubles every 5 years after 65. As many as half of people in their 80s have some loss of thinking ability.

Dementia vs. Alzheimer's

Alzheimer's disease (AD) is the most common cause of dementia. About 70%-80% of people with dementia have AD. But there are as many as 50 other causes of dementia.

Dementia symptoms may improve with treatment. But many of the diseases that cause dementia aren't curable.

Many people (about 40%) have at least some degree of memory loss as a normal part of aging. As we age, we all have slow changes to both our bodies and brains. For instance, we tend to lose some of our neurons (nerve cells that send messages throughout our body) as we get older. For most of us, memory loss doesn't affect our ability to live day-to-day or remain independent. A small degree of memory loss is known as age-associated memory impairment, and it causes memory problems that:

  • Don't disrupt your daily life
  • Don't affect your ability to complete your normal tasks
  • Don't affect your ability to learn or remember new things
  • Aren't caused by an underlying medical condition

A small percentage of people will develop dementia as they get older. Unlike people with normal aging, people with dementia will have memory loss that gets worse over time until they aren't able to take care of themselves.

Dementia is caused by damage to your brain cells, which can stop them from sending messages to one another. When your brain cells can't communicate, it can make it hard for you to think and feel, and it may change your behavior.

Your brain has several different regions that control different functions of your body. For instance, your cerebrum controls movement, body temperature, speech, thinking, reasoning, problem-solving, and emotions, among other things. When your brain cells are damaged in a specific part of your brain, that region can't control your body the way it should.

Several underlying medical conditions can cause damage that leads to dementia, including:

Alzheimer's disease (AD). This is the most common cause of dementia. In people with AD, pieces of a protein called amyloid cluster together to form plaques between their brain cells, and another protein called tau forms tangles inside their nerve cells. These proteins often start in the hippocampus, which is an area of your brain that controls how you form memories.

Over time, the plaques and tangles spread throughout the brain, leading to increased memory loss and trouble thinking. Eventually, individuals lose the ability to communicate and become dependent on others for their daily care.

Currently, some medicines can slow the progression of AD, but no treatment can completely stop the process or reverse it.

Vascular contributions to cognitive impairment and dementia (VCID). This is caused by the same risk factors that increase your risk for stroke, such as atrial fibrillation, hypertension, diabetes, and high cholesterol. Your symptoms will depend on where you have blood circulation problems in your brain, as well as how big they are, and how many you have.

There are several forms of VCID, including:

  • Vascular dementia
  • Vascular cognitive impairment
  • Poststroke dementia
  • Multi-infarct dementia
  • Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)
  • Subcortical vascular dementia (otherwise known as Binswanger's disease)
  • Cerebral amyloid angiopathy

Lewy body dementia (LBD). After AD and vascular causes, LBD is the next most common cause of dementia. It's caused by balloon-like clumps of abnormal proteins called Lewy bodies, which form in your nerve cells. People with LBD have problems with their thinking, behavior, body, and sleep. There are a couple of different types of LBD, including:

  • Dementia with Lewy bodies (DLB)
  • Parkinson's disease dementia (PDD)

Frontotemporal disorders (FTD). This is a group of neurodegenerative brain disorders that primarily affect the frontal and temporal lobes of your brain. Your frontal lobe partly controls your personality, decision-making, movement, and ability to smell and speak. Changes in this region of your brain would affect your ability to reason, make decisions, prioritize, multitask, act appropriately, and control movement. Your temporal lobe partly controls your short-term memory, speech, musical rhythm, and some of your ability to smell. Changes in this region of your brain affect your memory and your ability to understand the words that you hear, recognize things you've seen, and identify and respond to your emotions.

There are currently no treatments for curing or reversing FTD.

The signs and symptoms of FTD differ among people based on which area of the brain the disorder affects. There are several forms of FTD, including:

  • Behavioral variant frontotemporal dementia (bvFTD). This may or may not cause memory problems, but primarily affects behavior, judgment, and personality.
  • Primary progressive aphasia (PPA). This usually causes changes in the ability to speak, understand, write, read, and say what you're thinking.
  • Corticobasal degeneration (CBD). This causes nerve-cell loss and shrinking in your cerebral cortex and basal ganglia, which causes problems with your memory, behavior, thinking, language, and movement.
  • Frontotemporal dementia with motor neuron disease (FTD/MND or FTD-ALS). This is a combination of two disorders: bvFTD and amyotrophic lateral sclerosis (ALS). ALS causes damage to the nerve cells that let you control your body movements. You may have symptoms of either disorder at first, but they will gradually develop other symptoms.
  • Pick's disease. Pick bodies are balloon-like clumps of tau protein in your nerve cells. They cause inappropriate behavior, loss of speech, and trouble thinking.
  • Progressive supranuclear palsy (PSP). This causes some of the same symptoms as those in people with CBD and Parkinson's disease, such as trouble controlling your eye movements, mood swings, speech difficulties, trouble swallowing, vision problems, trouble concentrating, and language issues.

Other neurodegenerative diseases and conditions that have dementia or dementia-like symptoms include:

  • Argyrophilic grain disease
  • Creutzfeldt-Jakob disease (CJD)
  • Chronic traumatic encephalopathy (CTE)
  • Huntington's disease
  • HIV-associated dementia (HAD)
  • Secondary dementias due to multiple sclerosis, meningitis, encephalitis, Wilson's disease, and brain tumors

Some reversible causes of dementia-like symptoms include:

  • Alcohol or substance use disorder
  • Side effects of some medications
  • Tumors
  • Subdural hematomas, blood clots beneath the outer covering of the brain
  • Normal-pressure hydrocephalus, a buildup of fluid in the brain
  • Metabolic disorders, such as a vitamin B12 deficiency
  • Low levels of thyroid hormones, called hypothyroidism
  • Low blood sugar, called hypoglycemia
  • Vasculitis (inflammation of the blood vessels in your brain)
  • Chronic infections

Certain physical and lifestyle factors can raise your chances of dementia, including:

  • Your age
  • Family history of dementia
  • Illnesses including diabetes, Down syndrome, multiple sclerosis, heart disease, and sleep apnea
  • Depression
  • Lifestyle factors, such as smoking, heavy alcohol use, poor diet, and lack of exercise
  • Brain injury from accidents, high-impact sports, and military service
  • Strokes
  • Infection of the brain (for example, meningitis and syphilis)
  • Hearing loss
  • Low levels of some vitamins and nutrients such as vitamins D and B12
  • Sleep problems and disorders, including insomnia or dependence on sleep medications
  • Pollutants in your environment
  • Cognitive reserve, which is your brain's ability to handle diseases and comes from doing mentally stimulating work

Benadryl and dementia

Benadryl belongs to a class of medicines called anticholinergics. Anticholinergics block a chemical called acetylcholine, which helps transmit messages in your nervous system. Anticholinergic drugs include antihistamines (such as Benadryl), tricyclic antidepressants, as well as medicines for overactive bladder and Parkinson's disease.

Anticholinergic drugs have been linked to an increased risk of developing dementia. They probably don't directly cause dementia, but studies show that their long-term use may increase your risk of developing dementia. If you use an anticholinergic drug such as Benadryl, talk to your doctor about whether you should limit your use or change your medication.

People with dementia have problems with thinking and remembering things, which affects their ability to manage their daily lives.

Some signs to watch for include:

  • Short-term memory problems, such as forgetting where you put something or asking the same question over and over
  • Communication problems, such as the inability to speak and getting lost in areas that you're familiar with
  • Confusion and disorientation
  • Trouble with complex but familiar tasks, such as cooking a meal or paying your bills
  • Personality changes, such as depression, agitation, paranoia, and mood swings
  • Inappropriate behavior
  • Sleeping pattern changes
  • Trouble adapting to changes in your environment
  • Having hallucinations (seeing things that aren't there)
  • Having delusions (believing things that aren't true)
  • Feelings of paranoia and suspicion

Dementia is a progressive disease, which means that the signs and symptoms get worse over time, usually over years. However, the course can be different for every person with dementia. 

Doctors may describe its progress in three stages based on how much the symptoms affect day-to-day life. These stages are:

Early or mild stage. During this stage, your symptoms will start to affect your daily life. You will likely still be independent but might need a bit of help in your daily living. This may be a good time to make plans for your future, such as preparing a lasting power of attorney and advance directives to ensure your long-term wishes and preferences are clear for the people who will be on your care team.

If you're part of the care team for a person with dementia, at this stage it's important to focus on what the person can still do and involve them in their own care. For instance, try helping them make prompts and reminder lists and develop a routine that works for them.

Middle or moderate stage. During this stage, your symptoms become more noticeable and you will need more support in your daily life. For instance, many people in this stage may need reminders to bathe and change their clothes.

In addition to your memory and thinking getting worse, your behavior will often change and you may have delusions and hallucinations. It's often the longest-lasting stage. This is the stage at which many people move into assisted living or hire a caretaker to help them.

Late or severe stage. During this stage, you will probably need full-time care and support for your daily living, such as help eating, washing, and dressing. This tends to be the shortest stage. Most people will need to move into a care home that offers full-time support.

No one test can diagnose dementia. Your doctor will diagnose you based on your symptoms, medical history, physical exam, and cognitive tests.

Some tests your doctor may order include:

  • Blood and urine tests
  • Chest X-ray
  • PET, MRI, or CT scans to show your brain activity
  • Electroencephalogram (EEG)
  • Spinal fluid analysis
  • Neurological tests for memory

Your doctor will use certain criteria to diagnose dementia. These include impairment of:

  • Attention
  • Orientation
  • Memory
  • Judgment
  • Language, motor, and spatial skills and function
  • Overall mental health, as conditions such as major depression and schizophrenia can cause similar symptoms as dementia

Treatment for dementia generally focuses on managing the symptoms, especially the emotional and behavioral symptoms. Before trying medicine, your doctor may recommend the following:

Occupational therapy. An occupational therapist can teach you how to manage your or your loved one's behavior and make preparations for when dementia progresses. They can also teach you how to make your home safer and how to deal with the changes in behavior. They can also help you establish routines for memory training, physical exercise programs, and ways to keep yourself or your loved one mentally and socially stimulated.

Making helpful changes in your home and lifestyle. For instance, by cutting down on clutter and noise in the house, you can make it easier for your loved one with dementia to function and stay focused. You may need to hide objects, such as car keys and knives, that may be dangerous for your loved one to access. You may also consider installing monitoring systems that can let you know if your loved one wanders away.

Simplify tasks. Structure and routines help reduce confusion in people with dementia. Help your loved one come up with a schedule and stick to it. Break down their tasks into easy steps and celebrate the successes you achieve together.

Your doctor may also prescribe medicines such as antidepressants and antipsychotics to help with any emotional and behavioral symptoms.

Dementia medication

Most forms of dementia can't be cured or reversed. But for some forms, there are medicines available to help improve your thinking abilities and slow the progression of dementia.

Some FDA-approved medicines that may improve your thinking abilities and slow the progression of dementia include:

Cholinesterase inhibitors. These prevent your body from breaking down a brain chemical (neurotransmitter) called acetylcholine, which helps you remember, learn, pay attention, and move certain muscles. Cholinesterase inhibitors may slow or delay your symptoms from getting worse. These medicines don't work for everyone, and they can have serious side effects such as peptic ulcer disease, weight loss, and cardiovascular complications. Examples include:

  • Donepezil (Aricept), which is approved for people with all stages of AD
  • Galantamine (Razadyne), which is approved for people with mild to moderate stages of AD
  • Rivastigmine (Exelon), which is approved for all stages of AD as a patch and for mild to moderate stages as a capsule

Memantine. This is a medicine that decreases the activity of a neurotransmitter called glutamate, which is involved in memory formation. Like cholinesterase inhibitors, this medicine doesn't work for everyone.

Two drugs were recently FDA-approved to treat mild AD: Aducanumab-avwa (Aduhelm) and lecanemab-irmb (Leqembi). Both are monoclonal antibodies that lessen the buildup of the proteins called amyloid plaques in your brain. Doctors think these plaques are part of what leads to memory loss in people with AD. However, treating these plaques may or may not improve your symptoms. Talk to your doctor about whether these medicines will work in your situation.

To help with emotional and behavioral symptoms, your doctor may also prescribe antidepressants and antipsychotics.

If you have dementia, some lifestyle modifications can help you maintain your functioning for as long as possible. These may include:

  • Setting up a good sleep routine so you get enough good quality sleep
  • Eating a healthy, balanced diet
  • Exercising regularly
  • Treating any hearing or vision loss
  • Reducing stress and using healthy ways of dealing with stress
  • Keeping your blood sugar, blood pressure, and cholesterol in the normal range

Here are some healthy ways to deal with the stress of having a degenerative illness:

  • Learn more about memory loss, dementia, and the cause of your dementia.
  • Write about your feelings in a journal.
  • Join a support group.
  • See a therapist for individual and/or family counseling.
  • Talk to a member of your spiritual community.
  • Volunteer, exercise, and join the activities for people with memory loss.
  • Take up a new hobby, such as painting, singing, or writing.
  • Get help with decision-making from someone you trust.

If you are part of the care team for a loved one with dementia, here are some healthy measures you can take:

  • Learn more about your loved one's disease and join caregiver education programs.
  • Learn about supportive services for caretakers in your community.
  • Ask friends or family members for help and support.
  • Take care of your physical, emotional, and spiritual health.
  • Ask questions at medical and social care appointments, and stay in the loop with your loved one's entire care team.
  • Join a support group.

Both genetics and lifestyle choices can contribute to the development of dementia. While there is no way to prevent dementia completely, your lifestyle choices can help reduce your risk.

Lifestyle choices that can help prevent dementia include:

  • Adopting healthy behaviors during midlife (between ages 40 and 65)
  • Early and continuing education throughout life
  • Exercising regularly
  • Limited alcohol intake
  • Avoiding smoking
  • Staying socially active
  • Taking care of mental health
  • Eating a healthy diet to avoid high blood pressure, diabetes, and obesity
  • Protecting your hearing
  • Protecting your head from injuries
  • Avoiding highly polluted areas

Your risk of having complications from dementia increases as it progresses. Over time, dementia decreases your ability to function independently in your day-to-day life. For instance, dementia can lead to the following:

  • Inability to perform self-care tasks, such as bathing, dressing, brushing teeth and hair, using the toilet, and taking medicines. Your loved one will eventually need help doing these tasks.
  • Challenges with personal safety. People with middle- and late-stage dementia can't usually drive, cook, or live alone.
  • Trouble eating. Many people with dementia will have trouble chewing and swallowing, which can cause weight loss and dehydration.
  • Infections, such as pneumonia. Because of their trouble chewing and swallowing, people with dementia may inhale foods and drinks into their lungs, which can cause infections. People with late-stage dementia may fall very ill due to these infections that their body doesn't fight off as well as it once did.

This can vary widely because the neurodegenerative causes of dementia vary widely. Your age at diagnosis, the cause and severity of your dementia, and your personal lifestyle choices all contribute to how long you will live with dementia. Additional comorbidities and quality of care also play a role in your life expectancy.

The most common cause of dementia is AD, and the average life expectancy for someone with AD is about 8 years. However, many people with AD live much longer than that.

Dementia is a broad term to describe a set of symptoms that affect your cognitive functioning including memory, attention, thinking, communication, behavior, motor skills, and daily functioning. There are several types of dementia, each with many potential causes. An early diagnosis can help you get the right treatment, therapies, and support system for the best possible quality of life. Even with a dementia diagnosis, you can continue to enjoy life with the support of a team of health care workers, friends, and family.

Does a person with dementia know they are confused?

No, one of the characteristics of dementia is that the person who has it usually doesn't know that they have problems with their thinking abilities.