Delirium vs dementia: what’s the difference?

When someone you care about suddenly seems confused or begins having memory problems, it can be hard to know what’s happening. Dementia and delirium share some symptoms, but they are different cognitive health conditions. Understanding how they differ can help you recognize changes and know when to involve a medical professional.

What’s the difference between delirium and dementia?

Delirium usually begins suddenly, fluctuates throughout the day, and may be reversible when its underlying cause is treated. Dementia typically develops slowly, causes progressive cognitive decline, and is usually irreversible. Although changes in the aging brain may contribute to either condition, the timing and pattern of symptoms can help distinguish them.

Delirium 

• Symptoms begin suddenly 

• Temporary 

• Usually reversible once the underlying cause is identified 

• Symptoms fluctuate throughout the day and from day to day 

• Difficulty focusing or a short attention span

Dementia

• Symptoms begin slowly, unless it is rapid-onset dementia 

• Permanent 

• Usually irreversible and progressive 

• Symptoms are fairly consistent from day to day because of slow progression, unless they become severe, such as with sundowning 

• Memory problems and cognitive decline 

How to tell the difference between delirium and dementia

If you’re supporting an older adult, distinguishing delirium from dementia can be challenging because both conditions can cause confusion and cognitive impairment. If you suspect either condition, consult a medical professional immediately. Here’s a quick overview of the primary differences:

• Sudden onset of symptoms: Delirium often begins suddenly over hours or days, while dementia usually starts with subtle symptoms that progress slowly over months or years.

• Changes in symptoms: With delirium, symptoms can change significantly over a short period and often worsen in the evening. Dementia symptoms tend to remain stable or follow a steady decline.

• Attention: People experiencing delirium often have a marked reduction in attention and may become easily distracted. Although attention can also decline in the later stages of dementia, it’s usually preserved in the early stages.

• Fluctuations in alertness: With delirium, consciousness or alertness often fluctuates during the day, including periods of hypersomnia, or increased sleepiness, and hyperarousal. These fluctuations are less common with dementia unless delirium is also present.

• Memory loss: Memory loss is a core feature of dementia, especially memory loss involving recent events or newly learned information. It can also occur with delirium, but it may not be as prominent or consistent.

• Reversibility: Most of the time, delirium is temporary and reversible if its underlying cause is identified and treated. Dementia is a chronic, progressive condition.

Can someone have delirium and dementia at the same time?

Delirium superimposed on dementia refers to the onset of delirium in someone who already has a preexisting cognitive impairment, most often dementia.

For example, changes in the brain may make someone with dementia more susceptible to delirium in response to triggers such as a new medication, infection, surgery, or change in environment.

At the same time, an episode of delirium can intensify the symptoms of underlying dementia, making them appear worse than they are.

What is delirium?

Delirium is a sudden, acute change in mental function that goes well beyond the usual forgetfulness associated with aging. It’s often characterized by confusion, disorientation, difficulty focusing, hallucinations, or altered perceptions of reality. Because it causes such an abrupt change in mental state, it’s often considered a medical emergency and may resemble symptoms of critical conditions such as stroke, cancer, or infection.

Unlike dementia, which is a chronic and progressive cognitive disorder, delirium begins suddenly, usually within hours or days. It is often caused by a physical or mental illness and can be temporary and reversible. However, delirium may also signal that the brain is undergoing damage. Factors such as advanced age, prior brain disorders, visual or hearing impairment, and severe illness can make older adults more likely to develop delirium. Its effects can be frightening for the person experiencing it and for the people supporting them.

Delirium usually develops in older adults and can appear similar to Alzheimer’s disease, Lewy body dementia, or vascular dementia, even though they are distinct diagnoses.

Types of delirium

There are three types of delirium: hyperactive, hypoactive, and mixed. Knowing how each type may appear can help you recognize a sudden change.

• Hyperactive delirium is the most recognizable type. Symptoms include restlessness, agitation, and rapid mood changes. People experiencing this type of delirium may be hypervigilant and may also have hallucinations or delusions.

• Hypoactive delirium is the most common type among older adults and is often missed because it looks very different. People with this type of delirium may appear sleepy, lethargic, or indifferent. They may not respond normally to questions or other stimuli, may seem unfocused, and may slip in and out of consciousness. It is often mistaken for depression or general age-related decline.

• Mixed delirium combines symptoms of hyperactive and hypoactive delirium. A person may fluctuate between hyperactivity and hypoactivity, which can be confusing for family caregivers and health care providers. All three types involve sudden cognitive impairment, whether it appears as hyperactivity, hypoactivity, or a combination of both. Prompt diagnosis and treatment are crucial for managing delirium.

Symptoms of delirium

Symptoms can vary based on the type of delirium a person has. However, many people experiencing delirium show several common symptoms.

• Impaired cognition: This often appears as severe confusion, disorientation, or disorganized thinking. A person may not be aware of their surroundings or may find it difficult to follow conversations.

• Altered behavior: Behavior can range from hyperactivity, when someone seems restless and agitated, to hypoactivity, when they appear sluggish or immobile. Their speech patterns and coordination may also change.

• Hallucinations or delusions: Some people may have an altered perception of reality and, in extreme cases, see or hear things that aren’t there. These experiences can be vivid and distressing, adding to their confusion and fear.

• Rapid and unpredictable changes in symptoms: Delirium symptoms can change rapidly and unpredictably. Someone may seem fine one moment and confused the next. These swings between extremes are often worse at night, a phenomenon known as “sundowning.”

• Difficulty staying alert or awake: A person may alternate between periods of extreme drowsiness and alertness.

• Changes in sleep patterns: These may include difficulty falling or staying asleep, changes to the sleep-wake cycle, staying awake at night, or other irregular sleep patterns.

• Mood swings: Rapid changes in mood, such as sudden fear, anxiety, depression, or apathy, can also indicate delirium. Someone may become unusually quiet and withdrawn or appear anxious and unfocused.

• Short-term memory problems: While long-term memory may remain relatively intact, someone may struggle to remember recent events or learn new information. They may repeat questions, forget recent conversations, or misplace items.

What causes delirium?

Delirium can be caused by anything that strains the body’s homeostasis, or internal balance, especially in older adults. One of the most common risk factors is being over age 70. Delirium is also more prevalent in males.

• Infections: Older adults are more susceptible to infections, such as urinary tract infections or pneumonia, which have been proposed as causes of delirium.

• Medications: Certain medications, especially sedatives, narcotics, or medications used to treat Parkinson’s disease and depression, can trigger delirium.

• Metabolic imbalances: Electrolyte imbalances, thyroid dysfunction, or significant changes in body chemistry caused by kidney disease, liver disease, hypoglycemia, or thyroid disease can lead to delirium.

• Surgery or medical procedures: Delirium can occur after surgery or another major medical procedure, particularly one involving anesthesia or a stay in an intensive care unit.

• Alcohol or drug withdrawal: Withdrawal symptoms from alcohol or certain drugs can provoke delirium.

• Severe illness: Serious illnesses, including heart disease and lung disease, as well as severe pain, can precipitate delirium as the body responds to the condition.

• Environmental factors: Environmental changes, such as moving to a new home or being hospitalized, can trigger delirium in older adults, especially when they also have dementia.

Delirium often has more than one cause. A combination of factors may contribute to the condition.

Medication side effects, surgery, infection, dementia, intoxication, or withdrawal can cause delirium. Other possible causes include constipation, lack of sleep, pain, and imbalances such as low sodium.

How is delirium diagnosed?

Only a medical doctor can diagnose delirium. To make an accurate diagnosis, a doctor may complete a physical examination, order blood and urine tests or imaging tests such as MRI, CT, or X-rays, and review the person’s complete medical history. Tests may include:

• Cognitive tests: Health care providers use simple tasks to assess someone’s ability to pay attention, remember, and think clearly. For example, the person may be asked to recall a list of numbers or identify the current time and place.

• Assessment scales: One widely used test for delirium is the Confusion Assessment Method, or CAM. It evaluates whether there is an acute change in mental status, inattention, disorganized thinking, or an altered level of consciousness.

• Lab tests and imaging scans: Blood and urine tests can help identify infections, metabolic imbalances, or other underlying conditions that could cause delirium. If necessary, brain imaging tests, such as computerized tomography (CT), magnetic resonance imaging (MRI), or electroencephalograms (EEGs), may be used to check for brain abnormalities.

• Medication and substance review: A clinician may review all medications and substances the person uses, including prescription drugs, over-the-counter medications, supplements, alcohol, and narcotics. This can help determine whether drug interactions or withdrawal symptoms could be causing the delirium.

Delirium can be difficult to diagnose because it has many possible causes and can closely resemble other conditions. Because delirium can be dangerous and often signals an underlying issue, no episode should be ignored.

Can delirium be treated?

The short answer is that it depends. Treatment primarily focuses on addressing the underlying cause. This may include treating an infection, adjusting or discontinuing medications that contribute to delirium, correcting metabolic imbalances, or treating alcohol or drug withdrawal symptoms. Common treatment strategies include:

• Medical treatment: If an infection, metabolic disturbance, dehydration, or withdrawal from certain substances is contributing to delirium, that condition will need to be treated.

• Medication review: A careful medication review can identify drugs that may be causing or contributing to delirium. In some cases, medications may be reduced, discontinued, or changed.

• Supportive care: Supportive care can include keeping the person hydrated and well nourished, helping them maintain a normal sleep-wake cycle, and reducing the use of catheters or physical restraints that may increase agitation and confusion.

• Environmental modifications: A quiet, well-lit environment with visible clocks and calendars may help. Frequent reminders about the person, place, time, and situation may also be beneficial. In some cases, having a family member or family caregiver present can soothe someone experiencing delirium.

• Psychotherapy and behavioral interventions: Gentle reassurance, distraction, and relaxation techniques can help manage anxiety and the behavioral symptoms of delirium.

• Temporary use of medications: In some cases, medications may be used to control severe symptoms or prevent harm to the person or others. However, these are usually a last resort because of potential side effects.

Once delirium is diagnosed and its underlying cause is identified, a doctor may decide that an antipsychotic medication, such as haloperidol is the best way to manage it, or the doctor may recommend specialized care and monitoring until the delirium ends. There are no FDA-approved treatments specifically for delirium, and most medical professionals believe prevention is the best approach.

What is dementia?

Dementia is a general term for a decline in mental ability that is severe enough to interfere with daily life. It isn’t a specific disease. Instead, the term covers a wide range of medical conditions, including Alzheimer’s disease, that impair brain functions such as memory, thinking, and reasoning. Symptoms often include changes in personality, mood, and behavior.

Dementia typically affects older adults and results from damage to brain cells that affects their ability to communicate with one another. This can influence thinking, behavior, and emotions. Dementia isn’t a normal part of aging, although the risk increases with age.

Dementia is progressive, meaning it worsens over time, and there is currently no cure. However, treatments may slow its progression and improve quality of life. Alzheimer’s disease is the most common type, but other types include frontotemporal dementia and Lewy body dementia.

To learn more about how these conditions differ, read our article about the 10 types of dementia.

Symptoms of dementia

The causes and symptoms of dementia vary depending on the type a person has. However, some common early warning signs of dementia may include:

• Memory loss: Memory loss is often one of the first signs of dementia. Someone may forget recent events or information and ask for the same information repeatedly.

• Difficulty with complex tasks: Familiar tasks that require several steps, such as cooking a familiar recipe or paying bills, can become challenging.

• Difficulty with words and conversation: Someone may struggle to find the right words, repeat themselves, or have difficulty following conversations.

• Getting lost in familiar places: Difficulty navigating familiar areas or forgetting the way home can be a sign of dementia.

• Poor judgment: This may appear as difficulty making decisions, falling for scams easily, or neglecting personal hygiene.

• Mood and personality changes: You may notice unexplained changes in mood or behavior. These can include increased agitation, fearfulness, suspicion, or sudden periods of depression.

• Misplacing things: People with dementia may put items in unusual places and be unable to retrace their steps to find them. They may also accuse others of stealing.

• Confusion about time or place: Someone with dementia may lose track of dates, seasons, or time. They might also forget where they are or how they arrived there.

• Withdrawal from social activities: Someone may withdraw from hobbies, social activities, or workplace projects because they have trouble keeping up.

• Difficulty performing activities of daily living (ADLs): As dementia progresses, someone may find it more difficult to complete daily activities they once handled independently. These may include eating, bathing, dressing, using the toilet, or maintaining personal hygiene. The decline can be gradual and often depends on the stage and type of dementia. Each person experiences dementia differently, and symptom progression varies based on the type of dementia and the individual.

How is dementia diagnosed?

Like delirium, dementia is diagnosed by a medical doctor. A doctor may complete a physical examination and psychological assessment, order blood and urine tests or imaging tests such as MRI, CT, or X-rays, and review the person’s complete medical history. Standard tests for dementia may include:

• Medical history: The doctor will complete a detailed review of the person’s medical history and symptoms. They’ll likely ask about recent illnesses, other medical conditions, family medical history, and any difficulty the person has with daily activities.

• Physical examination: A doctor may conduct a physical examination to check for physical signs of dementia or clues about what could be causing the symptoms.

• Neurological tests: These tests can help doctors assess balance, sensory function, reflexes, and other neurological functions. They may also help identify signs of stroke, tumors, or other medical conditions that can affect brain function.

• Cognitive tests: These tests measure memory, problem-solving abilities, attention span, language skills, and math skills. They can help identify patterns associated with specific types of dementia.

• Brain scans: Imaging studies, such as magnetic resonance imaging (MRI), computed tomography (CT), or positron emission tomography (PET), can help identify strokes, tumors, or other structural and metabolic changes in the brain.

• Lab tests: Blood tests can help rule out other potential causes of memory loss and confusion, such as thyroid disorders or vitamin deficiencies.

Can dementia be treated?

While there is no cure for most types of dementia, treatments can help people manage symptoms and improve their quality of life. These may include antidepressants, antipsychotics, Alzheimer’s-specific drugs such as Aducanumab and Lacanemab and cholinesterase inhibitors such as Aricept or Exelon. The specific treatment plan depends on the type and cause of dementia. Common treatment approaches include:

• Medications: Several medications can temporarily improve symptoms by influencing chemicals that carry messages between brain cells. Donepezil, rivastigmine, and galantamine are used to treat Alzheimer’s disease by attempting to regulate acetylcholine, a chemical messenger involved in memory and judgment. Memantine is another drug often used to treat moderate to severe Alzheimer’s disease.

• Therapies: Nondrug interventions may help manage some dementia symptoms. For example, cognitive behavioral therapy may improve depression or anxiety. Occupational therapy may help someone learn coping behaviors, prevent accidents, manage behavior, and plan activities.

• Lifestyle adjustments: Regular physical activity, a healthy diet, avoiding alcohol and smoking, and maintaining an active social life may slow the progression of dementia in some cases. Cognitive activities such as puzzles, reading, or games may also support cognitive function.

• Care and safety considerations: Creating a safe and supportive environment can improve quality of life for people with dementia. Memory care communities are known for programming that provides engagement, support, and activities for people with memory-related diagnoses.

Treatments may improve symptoms and quality of life for some people with dementia, but they don’t stop or reverse the underlying disease process. Each person’s treatment plan may be tailored to their symptoms and needs.

Learning the differences between delirium and dementia is an important first step in supporting yourself or someone you care about. Both conditions can be difficult to diagnose and treat, so contact a medical professional immediately if you notice sudden confusion or other concerning cognitive changes.