Delirium is a sudden and severe deterioration of mental abilities characterized by confusion and a lack of awareness of one’s surroundings. It typically develops rapidly within a few hours or days and can be caused by various factors, including severe illness, imbalances in the body, certain medications, infections, surgeries, or alcohol/drug use or withdrawal. Distinguishing delirium from dementia can be challenging, and healthcare providers often rely on information from family members or caregivers to make an accurate diagnosis.

Delirium is a condition that involves a rapid decline in cognitive function, leading to difficulties in concentration and maintaining awareness. It occurs when there is widespread disruption in brain activity, often resulting from a combination of contributing factors. Delirium is commonly observed in medical settings, such as during prolonged hospital stays or in long-term care facilities.

The primary objective in treating delirium is to identify and address the underlying causes or triggers. This may involve discontinuing certain medications, treating infections, or correcting imbalances in the body. By addressing the root causes, healthcare professionals aim to alleviate the symptoms and improve the individual’s cognitive function and overall well-being.


Delirium typically manifests gradually over hours or days, often accompanying an underlying medical condition. Its symptoms fluctuate throughout the day, with periods of no symptoms. Nighttime and unfamiliar environments, like hospitals, can intensify symptoms. Delirium represents a broad disruption in brain activity, resulting in diverse manifestations. Symptoms vary among individuals and can change over time. Delirium’s misleading label of “sundowning” arises from its tendency to improve during the day but worsen as evening approaches.
The following are primary symptoms.

Reduced awareness of surroundings

This could lead to:

  • Difficulty staying focused or switching topics
  • Focusing on an idea rather than answering inquiries.
  • Being prone to distraction
  • Being reclusive, with little to no activity or reaction to the environment

Poor thinking skills

This could manifest as:

  • A bad memory that causes one to overlook recent events
  • Not knowing their identity or whereabouts
  • Issues speaking or remembering words
  • Speech that is incoherent or rambling
  • Difficulty comprehending speech, reading or writing

Behavior and emotional changes

These consists of:

  • Mistrust, fear, anxiety
  • Depression
  • Anger or a quick temper
  • An exhilarating sensation
  • Having no emotions or interest
  • Mood changes abruptly
  • Changes in personality
  • Perceiving details that others don’t see
  • Being agitated, fearful, or aggressive
  • Shouting, groaning, or making other noises
  • Being reserved and silent, particularly in senior adults
  • Slowing down or acting slow
  • Sleeping disturbances
  • A change night-day sleep-wake cycle

Types of delirium

Three types of delirium that have been recognized by experts:

  • Hyperactive delirium. Hyperactive delirium is a readily identifiable form of delirium. Its characteristics include restlessness, constant movement such as pacing, heightened anxiety, frequent mood swings, and visual hallucinations. Individuals experiencing hyperactive delirium often exhibit resistance towards receiving care.
  • Hypoactive delirium. Hypoactive delirium is another variant that can be easily recognized. Individuals with this type often display reduced activity levels or inactivity. They may appear sluggish, drowsy, or in a dazed state. Additionally, they typically exhibit a lack of interaction with family members or others around them.
    • Mixed delirium. As the name implies, combines characteristics of both hyperactive and hypoactive delirium. It typically manifests in one of the following ways:
    • Typical activity level: In this form, individuals remain confused and unaware of their surroundings, but their level of activity remains consistent with their usual behavior.
    • Shifting activity level: This type involves fluctuating between hyperactive and hypoactive symptoms. At times, the person may display hyperactive behaviors such as agitation or aggression, while other times they may exhibit hypoactive symptoms and sleep during the day.

Delirium and dementia

Delirium and dementia are distinct conditions with some similarities, but they have important differences. Delirium is characterized by fluctuating symptoms that can improve and worsen rapidly. On the other hand, dementia refers to a gradual and steady decline in cognitive abilities. Although delirium and dementia share similarities, it is crucial to recognize their distinctions. They can coexist and overlap, and individuals with dementia are at a higher risk of experiencing delirium. Additionally, delirium can accelerate the progression of dementia or exacerbate existing symptoms.

The following are some distinctions between dementia and delirium symptoms:

  • Onset. The first signs of delirium appear quickly, usually within a day or two. The symptoms of dementia typically start out mild and worsen with time.
  • Attention. Delirium impairs one’s capacity to focus or keep focus. A person with dementia in its early stages is typically alert. A person with dementia is frequently not lethargic or agitated.
  • Rapid changes in symptoms. Throughout the day, delirium symptoms can appear and disappear multiple times. While there are moments of the day when persons with dementia do better than others, their memory and cognitive abilities often remain steady.

If you observe symptoms of delirium in a relative, friend, or someone under your care, it is essential to communicate with their healthcare provider. Your input regarding their symptoms, cognitive abilities, and typical behavior will be valuable in diagnosing the condition and identifying its underlying cause.

In the case of individuals in hospitals or nursing homes, if you notice any signs of delirium, it is important to report your concerns to the nursing staff or healthcare provider. These symptoms may not have been previously observed, and older individuals in such settings are particularly vulnerable to delirium.


Delirium occurs when there is a disruption in the transmission and reception of signals in the brain. It can be caused by various factors, either individually or in combination. These include the use of certain medications or their side effects, alcohol or drug use or withdrawal, underlying medical conditions such as stroke, heart attack, deteriorating lung or liver disease, or injuries from falls. Imbalances in the body, like low sodium or calcium levels, severe and prolonged illnesses, fever and new infections (especially in children), urinary tract infections, pneumonia, flu, or COVID-19 (particularly in older adults), exposure to toxins such as carbon monoxide or cyanide, inadequate nutrition or excessive fluid loss, lack of sleep or extreme emotional distress, pain, and undergoing surgery or medical procedures requiring sedation.

Certain medications, whether used individually or in conjunction with others, have the potential to induce delirium. These include drugs employed for the management of pain, sleep disorders, mood-related conditions like anxiety and depression, allergies, asthma, swelling, Parkinson’s disease, as well as those prescribed for spasms or convulsions.

Risk factors

There are several factors that can increase the likelihood of developing delirium. These risk factors include:

  • Age: Individuals aged 65 and older are particularly susceptible to delirium due to natural aging processes that can affect brain function.
  • Dementia and degenerative brain diseases: People with existing conditions that affect brain function, such as dementia or other degenerative brain diseases, are more prone to delirium. These conditions contribute to the occurrence of delirium or increase the risk of its development.
  • Chronic physical conditions: Chronic diseases like heart disease and COPD place a strain on the body, making it more susceptible to delirium. The risk of delirium increases with the number of chronic conditions an individual has.
  • Mood disorders: A history of mood disorders, particularly depression, raises the risk of developing delirium.
  • Vision and hearing loss in older age: Declining vision and hearing impair the brain’s ability to perceive external cues, making delirium more likely to occur.
  • Alcohol and nonmedical drug misuse: Misuse of alcohol and nonmedical use of drugs like opioids and benzodiazepines significantly increase the risk of delirium.
  • Previous history of delirium: Individuals with a past episode of delirium are at higher risk of experiencing it again in the future.
  • Frailty: Frailty refers to a person’s vulnerability to illness or injury, which naturally increases with age. Physical frailty, especially in older individuals, makes them more susceptible to developing delirium.
  • Environmental change: Any condition that requires a hospital stay, particularly during recovery from surgery or in intensive care, raises the risk of delirium. Delirium is more common in older adults and individuals residing in nursing homes.