Delirium Vs. Dementia – Understanding The Differences

Medically reviewed by April Justice, LICSW
Updated May 27, 2024by BetterHelp Editorial Team
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As you age, some change may be inevitable. You may notice slight changes in your memory, problem-solving skills, and other abilities. While some changes are expected, more serious shifts in your mental state could be unsettling. These changes may be caused by dementia, which affects memory, problem-solving, language, and behavior, most commonly among older adults.

In conversations about dementia, you may have also heard the phrase “delirium” used to describe a sudden change in mental state. While the symptoms of dementia and delirium often overlap, it can be crucial to distinguish between these two conditions to ensure proper treatment. 

Below, we’re discussing the symptoms and risk factors of delirium and dementia, the differences between these conditions, and the treatment options available for people experiencing them.  

Trying to understand a diagnosis of dementia or delirium?

What is delirium? 

Delirium is a sudden, worsening change in a person’s mental state. According to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the diagnostic criteria for delirium include the following:  

  • A disturbance in attention, characterized by a reduced ability to direct, focus, sustain, and shift attention

  • Reduced awareness of one’s environment

As an onlooker or loved one, it can be distressing to watch someone experience delirium, especially if the cause of their symptoms is unclear. Healthcare providers may use various tools, such as the Confusion Assessment Method (CAM), which is used to identify delirium in people who may be at risk for dementia. This test can measure the severity and frequency of potential delirium symptoms, possibly leading to a diagnosis. 

Delirium superimposed on dementia

Delirium superimposed on dementia (DSD) is a condition in which an individual with pre-existing dementia experiences an acute delirious state. Diabetes, cerebrovascular disease, and the use of sedative drugs are a few of the independent risk factors for DSD. Diagnosis is challenging due to overlapping symptoms, often requiring an urgent evaluation for sudden changes in behavior and cognitive decline.


Mixed delirium is characterized by symptoms of both hyperactive and hypoactive delirium. Patients may have fluctuating levels of activity, from agitation to withdrawal, complicating treatment. Understanding the underlying pathophysiology involves recognizing the link between various triggers and brain dysfunction.


Hyperactive delirium is when someone becomes severely restless or agitated and may not cooperate with those trying to help them. The behaviors associated with hyperactive delirium are easier to spot but can be dangerous if not managed promptly.


Hypoactive delirium occurs when someone shows less activity, seems tired, and has trouble paying attention. It can be hard to notice, especially in patients who already have memory problems, and is often not recognized enough.


Substance-induced delirium arises from intoxication or withdrawal from drugs, including medications, alcohol, or illicit substances. The clinical picture depends on the substance involved and requires specific treatment for the intoxication or withdrawal process.


Infectious delirium occurs as a result of an acute infection, such as sepsis or pneumonia. Management involves treating the underlying infection alongside supportive care for delirium symptoms.


Postoperative delirium can develop after surgery, particularly in elderly patients or those with existing cognitive problems. Contributing factors include anesthesia, pain, stress, and disruption of normal routines.

What are the causes of delirium?

Health concerns that could cause delirium include:

  • Withdrawal from substances 

  • Substance intoxication, such as from illicit or prescribed drugs

  • An abnormal metabolism

  • Low salt or blood sugar levels

  • Visual or hearing impairment

  • Social isolation

  • Sensory deprivation

  • A traumatic experience 

  • Acute illness, such as an infection

  • An underlying medical condition, including epilepsy and insomnia 

  • Intense pain

Because the potential causes of delirium are varied, it can be crucial to see a medical provider who can rule out any serious or even life-threatening concerns.

What is dementia?

Dementia is the most significant risk factor for delirium. Dementia is an umbrella term for brain-related disorders that impact a person’s mental abilities, including memory, problem-solving, and language. This condition often affects older patients, usually over 65, and the symptoms may worsen over time. There are four main types of dementia, including the following. 

Alzheimer’s disease 

Alzheimer’s disease is the most common form of dementia. Often, the first signs of Alzheimer’s are changes in memory, thinking, language, or perception. 

Vascular dementia 

Vascular dementia is the second most common form of dementia and the most varied in its symptoms. While each person experiences it differently, common symptoms include difficulty planning, organizing, following steps, concentrating, and thinking quickly.    

Dementia with Lewy bodies (DLB)

Dementia with Lewy bodies (DLB) is caused by Lewy body disease. People with DLB develop clumps of protein, called Lewy bodies, in their brain cells. Over time, the build-up of Lewy bodies and other proteins in the brain can lead to delusions and difficulty with focus, movement, and sleep.

Frontotemporal dementia (FTD)

Frontotemporal dementia (FTD) is a less common form of dementia affecting personality, behavior, or language. In some cases, people are diagnosed with mixed dementia when they have symptoms of more than one type. 

What causes dementia?

At a biological level, dementia is caused by changes in specific brain regions that prevent nerve cells and their connections from working correctly. 

Researchers are still working to understand the reasons why certain people develop dementia. Across all types of dementia, rare genetic variants may increase the likelihood of developing these conditions, but these variants may only affect a small portion of people. Some healthcare providers might recommend genetic testing when diagnosing dementia to determine if genetic factors are contributing to the condition. 

In Alzheimer’s disease, scientists believe that the build-up of two proteins, amyloid and tau, forms deposits in the brain that lead to the loss of brain cells. Contrarily, vascular dementia is caused by reduced blood flow to the brain. This reduced flow may be caused by blocked blood vessels in the brain, a stroke, or a series of “mini” strokes that cause gradual, widespread damage to brain cells.

In dementia with Lewy bodies, the tiny clumps of protein that develop inside brain cells damage their ability to communicate with one another. In frontotemporal dementia, abnormal protein clumps cause damage to nerve cells in the front and temporal lobes of the brain, which leads to shrinkage of these areas.

Delirium vs. dementia

While delirium and dementia may be characterized by symptoms like memory problems, confusion, and visual hallucinations, they differ in several ways. Dementia develops slowly over months or years, while delirium usually has an abrupt onset and usually lasts for a few days. During that time, a person may become more confused, sleepier, or drowsier than usual. Patients with either condition are at a higher risk of complications, including increased mortality, highlighting the importance of consulting a doctor immediately if severe signs or symptoms arise.

Delirium may sometimes be a symptom of underlying dementia, but these two conditions are recognized as separate diagnoses in the DSM-5. When making a diagnosis, a doctor may carefully consider the similarities between delirium and dementia, which include confusion, agitation, and delusions. 

Because delirium and dementia are the two most common causes of altered mental states among older people, distinguishing delirium from dementia can be difficult, especially if delirium starts suddenly or occurs in someone with pre-existing dementia. A thorough physical examination is often required to make an accurate diagnosis and differentiate between dementia and delirium symptoms. A comprehensive evaluation of an individuals’ mental health status is also typically necessary.

Doctors can often diagnose accurately based on how quickly the symptoms appear or subside, how much symptoms change within a day, and other aspects of a person’s health that may influence this case. 

Treatment for delirium 

Depending on the cause of delirium, treatments can vary. In many cases, it’s recommended to prevent delirium in the first place. For example, healthcare professionals might recommend supportive measures, such as using hearing aids for someone in the hospital who has hearing problems, to prevent delirium. 

To treat delirium, a medical team might address medical concerns that could cause the condition. They might address low blood sugar, monitor your metabolism, prescribe antibiotics for an infection, or take other medical actions to stabilize your mental and physical health. Psychotherapy can also help individuals address the cognitive and emotional symptoms of delirium. With an accurate health assessment and a proactive, compassionate response, the symptoms of delirium often improve.

Treatment for dementia

Because dementia is progressive and comes in several varieties, its treatment is more complicated. While there is currently no cure for dementia, several interventions may help individuals manage the symptoms or slow down their progression. Some of these interventions include the following: 

  • Medications

  • Cognitive-stimulation therapy (CST)

  • Cognitive rehabilitation

In managing dementia, cholinesterase inhibitors are often prescribed to slow the progression of symptoms in conditions like Alzheimer's disease. These medications can help manage memory problems and confusion, which are common in dementia.

Using therapy to cope 

For people with dementia and their caregivers, the progression of symptoms can be distressing and isolating. However, you don’t need to explore treatment options alone. As you learn more about the diagnosis, a licensed therapist can provide emotional support and help you develop essential coping skills. While some people prefer face-to-face therapy, online therapy through platforms like BetterHelp is an increasingly popular option for people who want to invest in their mental health from home.  

Using an online platform, you can complete a brief questionnaire and get matched to a licensed therapist within 48 hours. In addition, you can use their worksheets, messaging, optional group sessions, and webinars. If your loved one has been diagnosed with dementia, delirium, or another serious condition, you may find that therapy helps you remain healthy and grounded, even while providing ongoing care to your loved one. 

Online therapy can also be highly effective. One study assessed the value of an online cognitive-behavioral therapy (CBT) program for family caregivers to people with dementia. After completing online CBT, the caregivers reported they were better able to manage the behavioral and psychological symptoms of dementia. The caregivers also reported being less distressed by those symptoms, and the dementia symptoms seemed to decrease in severity, possibly because they felt less anxious, stressed, and better equipped to communicate with their loved ones.


Whether experiencing these conditions directly or witnessing them in someone else, delirium and dementia can be upsetting, overwhelming experiences. However, the scientific understanding of both conditions is growing. Many therapists in the mental health community have years of experience working with people with dementia or delirium and the loved ones who walk alongside them.

The first step in treating delirium and dementia is understanding their differences. Early intervention, proper diagnosis, and various therapies can support you, whether you’re a caregiver or someone impacted. Consider reaching out to a professional to explore your experience in further detail.

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