Dementia: Types, Causes, Symptoms, Diagnosis & Treatment

Diseases & Conditions / 17/06/2025 / By
Dementia

Dementia is a general term used to describe a group of many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person’s ability to perform everyday activities. It affects your thinking, memory, reasoning, personality, mood and behavior. 

Dementia generally involves memory loss. It’s often one of the early symptoms of the condition. But having memory loss alone doesn’t mean you have dementia. Memory loss can have different causes.

Dementia develops when the parts of your brain involved with learning, memory, decision-making or language are affected by infections or diseases. The most common cause of dementia is Alzheimer’s disease.

About 5% to 8% of all people over the age of 65 have some form of dementia, and this number doubles every five years above that age. It’s estimated that as many as half of people 85 years of age and older have dementia. According to the World Health Organization (WHO), approximately 55 million people have dementia worldwide, with around 10 million new cases reported each year.

Some types of dementia are progressive. This means they get worse over time. Some types are treatable or even reversible. Some experts restrict the term “dementia” to irreversible mental deterioration.

There’s currently no cure, but researchers are looking into effective treatments and ways to prevent it.

Dementia entails a decline in mental function from a previously higher level that’s severe enough to interfere with daily living. A person with dementia has two or more of these specific difficulties, including a decline in:

  • Memory.
  • Reasoning.
  • Language.
  • Coordination.
  • Mood.
  • Behavior.

Key points about dementia

  • Dementia generally involves memory loss. It’s often one of the early symptoms of the condition.
  • Alzheimer’s disease is the most common type of dementia.
  • The general symptoms of dementia vary depending on the cause, stages, cognitive and psychological changes.
  • Dementia has many causes. In general, it results from the degeneration of neurons (brain cells) or disturbances in other body systems that affect how neurons function.
  • Dementia can’t be prevented, living a health-focused life might reduce risk factors for certain types of dementia.
  • Most types of dementia can’t be cured or reversed, and treatments provide only modest benefits.

Types of dementia

Dementia can be classified into three groups:

Primary (diseases and conditions in which dementia is the main illness)

Types of primary dementia include:

  • Alzheimer’s disease: This is the most common type of dementia. Two abnormal proteins build up in your brain: tau and amyloid proteins. These proteins disrupt communication between nerve cells in your brain. Nerve cells die, starting in one area and spreading as more nerve cells die in other areas. Symptoms include short-term memory loss, confusion, personality and behavior changes. Trouble talking, remembering distant memories and issues with walking happen later in the disease. Alzheimer’s disease mainly affects adults who are older — up to 10% of those over age 65 and about 50% of people older than 85 have the disease. Family history is an important risk factor. Approximately 60% to 80% of people with dementia have this type.
  • Vascular dementia: This is the second most common type of dementia. It’s caused by conditions such as strokes or atherosclerosis, which block and damage blood vessels in your brain. Symptoms include memory problems, confusion and trouble concentrating and completing tasks. The decline may appear suddenly (following a major stroke) or in steps (following a series of mini strokes). Risk factors include high blood pressure, diabetes and high cholesterol levels. About 15% to 25% of people with dementia have vascular dementia.
  • Lewy body dementia: This condition involves the buildup of clumps of proteins — called Lewy bodies — in your brain’s nerve cells. Lewy bodies damage nerve cells. Symptoms include movement and balance problems, changes in sleep patterns, memory loss, planning and problem-solving difficulties, and visual hallucinations and delusions. About 5% to 10% of dementias are Lewy Body dementia.
  • Frontotemporal dementia (FTD): This dementia results from damage to the frontal and temporal lobes of your brain. The damage is caused by the buildup of abnormal proteins in these areas. It causes changes in social behavior, personality, and/or loss of language skills (speaking, understanding or forgetting the meaning of common words) or motor coordination. FTD is a common cause of early dementia, often occurring in people between the ages of 45 and 64. Between 5% and 6% of all dementias are FTD.
  • Mixed dementia: This is a combination of two or more types of dementia. The most common combination is Alzheimer’s disease with vascular dementia. It’s most common in people 80 years of age and over. It’s often hard to diagnose because symptoms of one dementia may be more obvious and/or many symptoms of each type overlap. The decline is faster in people who have mixed dementia compared with those who only have one type.

Secondary (dementia due to another disease or condition)

Other causes of dementia include:

  • Huntington’s disease: A single defective gene causes this brain disorder. The disease causes a breakdown in your brain’s nerve cells, which causes body movement control problems, as well as thinking, decision-making and memory trouble, and personality changes.
  • Parkinson’s disease: Many people in the later stages of Parkinson’s disease develop dementia. Symptoms include trouble with thinking and memory, hallucinations and delusions, depression and trouble with speech.
  • Creutzfeldt-Jakob disease: This rare infective brain disease affects about only 1 in 1 million people. An abnormal protein in your brain called prions causes the disease. These prions clump together and cause nerve cell death in your brain. Symptoms include problems with thinking, memory, communication, planning and/or judgment, confusion, behavior changes, agitation and depression.
  • Wernicke-Korsakoff syndrome: This brain disorder is caused by a severe thiamine (vitamin B1) deficiency. This can result in bleeding in key areas related to memory in your brain. It’s most commonly caused by alcohol use disorder but can also be due to malnutrition and chronic infection. Symptoms include double vision, loss of muscle coordination, and difficulty processing information, learning new skills and remembering things.
  • Traumatic brain injury: Repeated blows to your head can cause this injury. It’s most often seen in football players, boxers, soldiers and people who’ve had a vehicle accident. Dementia symptoms, which appear years later, include memory loss, behavior or mood changes, slurred speech and headaches.

Reversible dementia-like symptoms caused by other illnesses or causes

Some conditions can cause dementia-like symptoms that can be reversed with treatment, including:

  • Normal pressure hydrocephalus (NPH): This condition happens when cerebrospinal fluid (CSF) builds up in your brain’s spaces (ventricles). The excess buildup harms your brain. NPH can be caused by a brain infection, brain injury, brain bleed or previous brain surgery. Symptoms include poor balance, forgetfulness, trouble paying attention, mood swings, frequent falls and loss of bladder control. Your healthcare provider can drain excess fluid through the surgical placement of a shunt (tube).
  • Vitamin deficiency: Not getting enough vitamin B1, B6, B12 cooper and vitamin E in your diet can cause dementia-like symptoms.
  • Infections: Infections that can cause dementia-like symptoms include HIV infection, syphilis and Lyme disease. Symptoms reported with COVID-19 infection include “brain fog” and acute delirium. Because of the inflammation and stroke risk seen with COVID-19 infection, both short- and long-term cognitive effects are being investigated. Urinary tract infections (UTIs) and infections in your lungs in the elderly can also result in dementia-like symptoms. Other central nervous system infections and brain infections caused by fungi, bacteria and parasites can also cause cognitive symptoms.
  • Metabolic and endocrine conditions: Conditions that can mimic dementia include Addison’s disease, Cushing’s disease, low blood sugar (hypoglycemia) exposure to heavy metals (like arsenic or mercury), high calcium levels (hypercalcemia, often due to hyperparathyroidism), liver cirrhosis and thyroid problems.
  • Medication side effects: Some medications, in some people, can mimic dementia symptoms. These include sleeping pills, anti-anxiety drugs, antidepressants, anti-seizure drugs, antiparkinson drugs, nonbenzodiazepine sedatives, narcotic pain relievers, statins and others. Ask your healthcare provider to review your medications if you have any dementia-like symptoms.
  • Other causes: Other causes of dementia-like symptoms include brain tumors and subdural hematomas (brain bleeds between your brain’s surface and the covering over your brain).

Stages of dementia

In most cases, dementia is progressive, getting worse over time. That said, dementia progresses differently in everyone. However, most people experience symptoms of the following stages of dementia.

Mild cognitive impairment

Older adults may develop mild cognitive impairment (MCI) but may never progress to dementia or any other mental impairment. People with MCI commonly experience forgetfulness, trouble recalling words, and short-term memory problems.

Mild dementia

At this stage, people with mild dementia may be able to function independently. Symptoms include:

  • short-term memory lapses
  • personality changes, including anger or depression
  • misplacing things or forgetfulness
  • difficulty with complex tasks or problem solving
  • difficulty expressing emotions or ideas

Moderate dementia

At this stage of dementia, people affected may need assistance from a loved one or care professional. That’s because dementia may now interfere with daily tasks and activities. Symptoms include:

  • poor judgment
  • increasing confusion and frustration
  • memory loss that reaches further into the past
  • needing help with tasks like dressing and bathing
  • significant personality changes

Severe dementia

At this late stage of dementia, the mental and physical symptoms of the condition continue to worsen. Symptoms include:

  • inability to maintain bodily functions, including walking and eventually swallowing and controlling the bladder
  • inability to communicate
  • requiring full-time assistance
  • increased risk of infections

People with dementia will progress through the stages of dementia at different rates.

Symptoms of dementia

The general symptoms of dementia vary depending on the cause, stages, cognitive and psychological changes.

Early symptoms of dementia include:

  • Forgetting recent events or information.
  • Repeating comments or questions over a very short period.
  • Misplacing commonly used items or placing them in unusual spots.
  • Not knowing the season, year or month.
  • Having difficulty coming up with the right words.
  • Experiencing a change in mood, behavior or interests.

Signs that dementia is getting worse include:

  • Your ability to remember and make decisions further declines.
  • Talking and finding the right words becomes more difficult.
  • Daily complex tasks, such as brushing your teeth, making a cup of coffee, working a TV remote, cooking and paying bills become more challenging.
  • Lessening of rational thinking and behavior and your ability to problem-solve.
  • Sleeping pattern changes.
  • Increases or worsening of anxiety, frustration, confusion, agitation, suspiciousness, sadness and/or depression.
  • Needing more help with activities of daily living, such as grooming, toileting, bathing and eating.
  • Experiencing hallucinations (seeing people or objects that aren’t there).

These symptoms are general symptoms of dementia. Each person diagnosed with dementia has different symptoms, depending on what area of their brain is damaged. Additional symptoms and/or unique symptoms occur with specific types of dementia.

Stages and Symptoms of Alzheimer’s disease

Causes of dementia

Dementia has many causes. In general, it results from the degeneration of neurons (brain cells) or disturbances in other body systems that affect how neurons function.

Several conditions can cause dementia, including diseases of the brain. The most common causes are Alzheimer’s disease and vascular dementia.

Some of the most common causes of dementia include:

Neurodegenerative diseases

“Neurodegenerative” means that neurons gradually stop functioning or function inappropriately and eventually die. 

This affects the neuron-to-neuron connections, called synapses, which are how messages are passed along in your brain. This disconnect can result in a range of dysfunction such as:

Another cause is frontotemporal lobar degeneration. This is a blanket term for a range of conditions that cause damage to the frontal and temporal lobes of the brain. They include:

  • frontotemporal dementia
  • Pick’s disease
  • supranuclear palsy
  • corticobasal degeneration

Other causes of dementia

Dementia has other causes, including:

  • structural brain disorders, such as normal pressure hydrocephalus and subdural hematoma
  • metabolic disorders, such as hypothyroidism, vitamin B12 deficiency, and kidney and liver disorders
  • toxins, such as lead
  • certain tumors or infections of the brain
  • medication side effects

Some of these types of dementia may be reversible. These treatable causes of dementia may reverse symptoms if they’re caught early enough. This is one of the many reasons why it’s important to contact your doctor and get a medical workup as soon as symptoms develop.

Risk factors of dementia

Many factors can eventually contribute to dementia. Some factors, such as age, can’t be changed. You can address other factors to reduce your risk.

Risk factors that can’t be changed

  • Age. The risk of dementia rises as you age, especially after age 65. However, dementia isn’t a typical part of aging. Dementia also can occur in younger people.
  • Family history. Having a family history of dementia puts you at greater risk of developing the condition. However, many people with a family history never develop symptoms, and many people without a family history do. There are tests to determine whether you have certain genetic changes that may increase your risk.
  • Down syndrome. By middle age, many people with Down syndrome develop early-onset Alzheimer’s disease.

Risk factors you can change

You might be able to control the following risk factors for dementia.

  • Diet and exercise. Research has found that people at higher risk of dementia who followed a healthy lifestyle lowered their risk of cognitive decline. They ate a diet that included fish, fruits, vegetables and oils. They also exercised, had cognitive training and participated in social activities. While no specific diet is known to reduce dementia risk, research indicates that those who follow a Mediterranean style diet rich in produce, like whole grains, nuts and seeds have better cognitive function.
  • Drinking too much alcohol. Drinking large amounts of alcohol has long been known to cause brain changes. Several large studies and reviews found that alcohol use disorders were linked to an increased risk of dementia, particularly early-onset dementia.
  • Cardiovascular risk factors. These include obesity, high blood pressure, high cholesterol, and the buildup of fats in the artery walls, known as atherosclerosis. Diabetes and smoking also are cardiovascular risk factors. Having diabetes can increase the risk of dementia, especially if it’s poorly controlled. Smoking might increase the risk of developing dementia and blood vessel disease.
  • Depression. Although not yet well understood, late-life depression might indicate the development of dementia.
  • Air pollution. Studies in animals have indicated that air pollution particulates can speed degeneration of the nervous system. And human studies have found that air pollution exposure — particularly from traffic exhaust and burning wood — is associated with greater dementia risk.
  • Head trauma. People who’ve had a severe head trauma have a greater risk of Alzheimer’s disease. Several large studies found that in people age 50 years or older who had a traumatic brain injury (TBI), the risk of dementia and Alzheimer’s disease increased. The risk increases in people with more-severe and multiple TBIs. Some studies indicate that the risk may be greatest within the first six months to two years after the TBI.
  • Sleep problems. People who have sleep apnea and other sleep disturbances might be at higher risk of developing dementia.
  • Low levels of certain vitamins and nutrients. Low levels of vitamin D, vitamin B-6, vitamin B-12 and folate can increase the risk of dementia.
  • Medicines that can worsen memory. These include sleep aids that contain diphenhydramine (Benadryl) and medicines to treat urinary urgency such as oxybutynin (Ditropan XL). Also limit sedatives and sleeping tablets. Talk to a health care professional about whether any of the medicines you take might make your memory worse.

Alcohol use may be the most preventable risk factor for dementia. A 2018 study found that the majority of early onset dementia cases were related to alcohol use.

Causes and Risk Factors of Stroke

Complications of dementia

Your brain controls all of your body’s functions. When your brain functions decline, your overall health is eventually at risk. Many illnesses and conditions can happen as a result of having dementia.

Dementia may lead to:

Inability to perform self-care tasks. As dementia gets worse, people have a hard time bathing, dressing, and brushing their hair or teeth. They need help using the toilet and taking medicines as directed.

Personal safety challenges. Some day-to-day situations can present safety issues for people with dementia. These include driving, cooking, and walking and living alone.

Death. Coma and death can occur in late-stage dementia. This often happens because of an infection.

Prevention of dementia

Although dementia can’t be prevented, living a health-focused life might reduce risk factors for certain types of dementia.

A 2017 review found that more than one-third of dementia cases may be the result of lifestyle factors. 

Keeping blood vessels clear of cholesterol buildup, maintaining normal blood pressure, maintaining healthy blood sugar levels, staying at a healthy weight — basically, staying as healthy as you can — can keep your brain fueled with the oxygen and nutrients it needs to function at its highest possible level. Specific healthful steps you can take include:

  • Stop smoking.
  • Follow a Mediterranean diet, which is one filled with whole grains, vegetables, fruits, fish and shellfish, nuts, beans, olive oil and only limited amounts of red meats.
  • Exercise. Get at least 30 minutes of exercise most days of the week.
  • Keep your brain engaged. Solve puzzles, play word games and try other mentally stimulating activities. These activities may delay the start of dementia.
  • Stay socially active. Interact with people, discuss current events, and keep your mind, heart and soul engaged.
  • Manage cardiovascular risk factors. Treat high blood pressure, high cholesterol and diabetes. Lose weight if you’re overweight.
  • Get good-quality sleep. Practice good sleep hygiene. Talk to a health care professional if you snore loudly or have periods where you stop breathing or gasp during sleep.
  • Treat hearing problems. People with hearing loss have a greater chance of developing problems with thinking, known as cognitive decline. Early treatment of hearing loss, such as use of hearing aids, might help decrease the risk.

Complications and Prevention of High Blood Pressure

Diagnosis of dementia

Confirming a diagnosis of dementia can be difficult. Many diseases and conditions can cause or lead to dementia. In addition, many of its symptoms are common to many other illnesses.

A healthcare professional reviews your medical history and symptoms and conducts a physical exam. Someone who is close to you may be asked about your symptoms as well.

Your healthcare provider will:

  • Ask about the course of your symptoms.
  • Ask about your medical history.
  • Review your current medications.
  • Ask about your family history of disease including dementia.

No single test can diagnose dementia. You’ll likely need a number of tests that can help pinpoint the problem. These include:

Laboratory tests

Laboratory tests rule out other diseases and conditions as the cause of dementia, such as infection, inflammation, underactive thyroid and vitamin deficiency (especially B12).

Sometimes, healthcare providers order cerebrospinal fluid tests to evaluate autoimmune conditions and neurodegenerative diseases, if warranted.

Imaging tests

Your healthcare provider may order the following imaging tests of your brain:

  • Computed tomography (CT) and magnetic resonance imaging (MRI): CT uses X-rays and a computer to show detailed images of your brain. MRI uses magnets, radio frequencies and a computer to create detailed images of your brain. These imaging tests look for evidence of stroke, bleeding, tumors and fluid on your brain.
  • FDG-PET scan: This is a special type of brain scan that aids in determining brain function and cognitive decline by the pattern of how a type of glucose is absorbed by brain tissue, and is sometimes needed in specific diagnoses.

Neurocognitive testing

During neurocognitive testing, your healthcare provider uses written and computerized tests to evaluate your mental abilities, including:

  • Problem solving.
  • Learning.
  • Judgment.
  • Memory.
  • Planning.
  • Reasoning.
  • Language.

Psychiatric evaluation

A mental health professional may check for signs of depression, mood changes or other mental health issues that might cause memory loss.

Treatment of dementia

First, it’s important to understand the terms “treatable,” “reversible” and “curable.” All or almost all forms of dementia are treatable using medications and other measures, which can help manage your symptoms. However, most types of dementia can’t be cured or reversed, and treatments provide only modest benefits.

Two primary treatments are used to alleviate symptoms of dementia: medications and non-drug therapies. Not all medications are approved for each type of dementia.

Fortunately, some types of dementia, like those brought on by treatable causes, may be successfully reversed. These dementia-like symptoms are caused by:

  • Side effects of medications, illicit drugs or alcohol.
  • Tumors that can be removed.
  • Subdural hematoma (a buildup of blood beneath the outer covering of your brain that’s caused by a head injury).
  • Normal pressure hydrocephalus (a buildup of cerebrospinal fluid in your brain).
  • Metabolic disorders, such as a vitamin B12 deficiency.
  • Hypothyroidism, a condition that results from low levels of thyroid hormones.
  • Hypoglycemia (low blood sugar).
  • Depression.

Dementias that aren’t reversible may still partially respond to medications that treat memory loss or behavior problems. These dementias include:

  • Alzheimer’s disease.
  • Multi-infarct (vascular) dementia.
  • Dementias associated with Parkinson’s disease and similar disorders.
  • AIDS dementia complex.
  • Creutzfeldt-Jakob disease.

Medications

The following are drugs approved for the most common form of dementia, Alzheimer’s disease and others:

  • Cholinesterase inhibitors. These medicines work by boosting levels of a chemical messenger involved in memory and judgment. They include donepezil (Aricept, Adlarity), rivastigmine (Exelon) and galantamine (Razadyne ER). Although primarily used to treat Alzheimer’s disease, these medicines also might be prescribed for other dementias. They might be prescribed for people with vascular dementia, Parkinson’s disease dementia and Lewy body dementia. Side effects can include nausea, vomiting and diarrhea. Other possible side effects include slowed heart rate, fainting and sleep problems.
  • NMDA receptor antagonist Memantine. Such as Namenda, works by regulating the activity of glutamate. Glutamate is another chemical messenger involved in brain functions such as learning and memory. Memantine is sometimes prescribed with a cholinesterase inhibitor. A common side effect of memantine is dizziness.
  • Anti-amyloid antibody aducanumab (Aduhelm). Aducanumab targets amyloid proteins, which build up into the plaques seen in the brains of people with Alzheimer’s disease.
  • Other medicines. You might take other medicines to treat symptoms or other conditions. You may need treatment for depression, sleep problems, hallucinations, parkinsonism or agitation.

Although none of these drugs appear to stop the progression of the underlying disease, they may slow it down.

If other medical conditions are causing dementia or co-exist with dementia, healthcare providers prescribe the appropriate drugs used to treat those specific conditions. These other conditions include sleeping problems, depression, hallucinations and agitation.

Non-drug therapies

These therapies may help reduce symptoms of dementia and alleviate some of the manageable complications of the condition. Common non-drug treatments for dementia include:

  • Occupational therapy. An occupational therapist can show you how to make your home safer and teach coping behaviors. The purpose is to prevent accidents, such as falls. The therapy also helps you manage behavior and prepare you for when the dementia progresses.
  • Changes to the environment. Reducing clutter and noise can make it easier for someone with dementia to focus and function. You might need to hide objects that can threaten safety, such as knives and car keys. Monitoring systems can alert you if the person with dementia wanders.
  • Simpler tasks. Breaking tasks into easier steps and focusing on success, not failure, can be helpful. Structure and routine help reduce confusion in people with dementia. You can work with a therapist or other healthcare professional to break down everyday activities, such as showering or grooming, into manageable tasks.

Diagnosis and Symptoms of High Cholesterol

Dementia and Alzheimer’s disease

Dementia and Alzheimer’s disease are not the same. Dementia is an umbrella term used to describe a collection of symptoms related to memory, language, and decision making.

Alzheimer’s disease is the most common type of dementia. It causes difficulty with things like:

  • short-term memory
  • depression
  • disorientation
  • behavioral changes

Dementia causes symptoms such as:

  • forgetfulness or memory impairment
  • loss of sense of direction
  • confusion
  • difficulty with personal care

The exact constellation of symptoms will depend on the type of dementia you have.

Alzheimer’s disease can also cause these symptoms, but other symptoms of Alzheimer’s may include depression, impaired judgment, and difficulty speaking.

Likewise, treatments for dementia depend on the type you have. However, Alzheimer’s disease treatments often overlap with other nonpharmacological dementia treatments.

In the case of some types of dementia, treating the underlying cause may be helpful in reducing or stopping the memory and behavior problems. However, that is not the case with Alzheimer’s disease.

Comparing the two may help you tell the difference between symptoms you or a loved one may be experiencing.

Individuals living with dementia can and do live for years after their diagnosis. It may seem that dementia is not a fatal disease because of this. However, late-stage dementia is considered terminal.

It’s difficult for doctors to predict life expectancies in people with dementia. Likewise, factors that influence life expectancy may have a different impact on the length of life in each person.

In a 2015 study , women diagnosed with Alzheimer’s disease lived an average of 5.7 years after diagnosis. Men lived 4.2 years. Life expectancies, the study found, may be shorter for individuals with other types of dementia.

Certain risk factors increase the likelihood of death in people with dementia. These factors include:

  • increased age
  • being born male
  • decreased capabilities and functionality
  • additional medical conditions, diseases, or diagnoses, such as diabetes or cancer

However, it’s important to remember that dementia doesn’t follow a specific timeline. You or your loved one may progress through the stages of dementia slowly, or the progression may be rapid and unpredictable. This will affect life expectancy.

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