Delirium is an acute neuropsychiatric syndrome that occurs particularly in the elderly population, in individuals receiving hospital treatment, or in those with serious medical illnesses, leading to sudden changes in attention, consciousness, awareness, and thought processes. Early diagnosis and appropriate treatment are of great importance in terms of identifying the medical condition causing delirium and preventing potential complications.
Delirium is characterized by fluctuations in the level of consciousness, attention deficit, reduced environmental awareness, and sudden changes in cognitive functions. Often confused in the community with Dementia, Alzheimer's, or psychiatric diseases, delirium frequently indicates the acute impact of an underlying infection, metabolic disorder, drug effect, oxygen deficiency, or neurological disease on brain functions.
In modern medicine, delirium is not evaluated merely as "confusion" or a temporary alteration in mental state. Delirium is a clinical condition that emerges through the temporary impairment of the brain's attention, awareness, and cognitive control systems due to systemic diseases, infections, surgical processes, metabolic imbalances, or medications. Therefore, early diagnosis and rapid identification of the cause are important both for the patient's safety and for the proper planning of the treatment process.
Sudden changes in consciousness and behavior occurring particularly in elderly individuals should not be evaluated as a "natural consequence of aging." Although delirium is a treatable condition in many cases, the underlying cause must be investigated without delay, and the patient must be evaluated medically.
What is Delirium?
Delirium is an acute neuropsychiatric condition with sudden onset that affects attention, consciousness, perception, orientation, thinking and behavior, and may fluctuate over the course of the day. Clinically also described as an “acute confusional state”, delirium usually emerges as a temporary response of the brain to medical factors such as infection, metabolic imbalance, drug effects, insufficient oxygen or surgical stress.
The key feature of delirium is that it begins within a short time and the symptoms become evident within hours or days. During this period, it may become difficult for the patient to sustain attention, perceive the surroundings correctly, follow conversations and correctly judge where they are or what time it is. For this reason, delirium should not be regarded merely as “forgetfulness” or “restlessness”, but as a serious clinical condition affecting the brain's attention and awareness systems.
The main features that may be seen during delirium are as follows:
- Inattention and impaired concentration
- Fluctuation in the level of consciousness
- Disorganized thought processes
- Short-term memory problems
- Perceptual disturbances and misinterpretations
- Changes in the sleep-wake cycle
- Fluctuations in behavior and mood
How Does Delirium Develop?
Temporary disruptions in the chemical signaling that regulates the brain's attention, awareness and alertness systems play a role in the development of delirium. In particular, a decrease in acetylcholine levels and an increase in dopamine activity are associated with symptoms seen during delirium, such as impaired attention, perceptual changes and restlessness.
In addition, the following conditions may affect brain function and set the stage for delirium:
- Systemic infections
- Hypoxia (insufficient oxygen)
- Electrolyte disturbances
- Metabolic diseases
- Drug toxicities
- Surgical procedures
In recent years, neuroinflammation has also been recognized as an important mechanism in the development of delirium. The inflammatory response that develops in the body during an infection or severe systemic illness may affect the blood-brain barrier and the communication between nerve cells, causing temporary disturbances in consciousness, attention and behavior.
How Quickly Does Delirium Begin?
Delirium usually develops within hours or a few days. This sudden onset is one of the most important clinical features that distinguishes delirium from chronic cognitive disorders such as dementia, which progress over months or years.
Symptoms of delirium:
- May begin within a few hours.
- May worsen and ease over the course of the day.
- May become more pronounced in the evening and at night.
- May persist for days or weeks if the underlying cause is not treated.
For this reason, confusion, impaired attention, loss of orientation or altered consciousness that appears within a short time should not be dismissed as “temporary absent-mindedness”; it should be regarded as a finding that requires medical evaluation.
What are the Symptoms of Delirium?
Symptoms of delirium may vary from person to person. The patient's age, existing neurological or systemic diseases, the medications used and the underlying cause of the delirium may affect the severity of the symptoms. The most prominent feature of delirium is that changes in the level of attention and awareness begin suddenly and fluctuate during the day.
Attention and Focusing Problems
Impaired attention is one of the core findings of delirium. The patient may have difficulty following conversations, giving appropriate answers to questions or keeping their attention on a particular subject.
In patients:
- Inability to follow conversations
- Delayed or inappropriate answers to questions
- Easily drifting off the subject
- Loss of concentration
- Inability to complete simple tasks
Symptoms such as these may be observed. One of the first changes noticed by healthcare staff or relatives is that the person becomes more absent-minded than usual and has difficulty focusing.
Changes in Consciousness and Awareness
During delirium, a person's interaction with their surroundings and their level of alertness may change. While some patients appear drowsy and unresponsive, others may show marked restlessness and exaggerated reactions to environmental stimuli.
Changes that may be observed:
- Reduced response to environmental stimuli
- Change in the level of alertness
- Feeling of grogginess
- Clouding of consciousness
- Level of awareness fluctuating during the day
These symptoms may not remain constant; the patient may appear better during part of the day and noticeably more confused or restless at another time.
Impaired Perception of Time and Place
People experiencing delirium may develop disorientation. This means the person has difficulty correctly judging where they are, what day it is or who the people around them are.
For example:
- They may mistake the hospital for home.
- They may perceive night as day.
- They may confuse the date or the time.
- They may have difficulty recognizing people close to them.
This impairment in the perception of time and place may become more pronounced especially in elderly patients and in the hospital setting.
Changes in Behavior and Mood
Behavioral symptoms in delirium are highly variable. While restlessness, anxiety and agitation are prominent in some patients, others may show quietness, withdrawal and reduced interest in their surroundings.
In patients:
- Restlessness
- Irritability
- Anxiety
- Agitation
- Sudden outbursts of anger
- Emotional fluctuations
may be observed. These changes should not be interpreted as personality traits; especially if they began suddenly, they should be evaluated for an underlying medical cause.
Hallucinations and Perceptual Disturbances
During delirium, Hallucinations and perceptual disturbances may develop. The patient may perceive people, objects or images that are not actually there, or may misinterpret events in their surroundings.
The most common are:
- Visual hallucinations
- Auditory perceptual disturbances
- Misinterpretations
- Seeing objects or people that are not real
Visual hallucinations may be more prominent especially in delirium caused by infection, drug effects, alcohol withdrawal or metabolic disturbances.
Changes in the Sleep and Wake Pattern
Disruption of the sleep-wake cycle is one of the important symptoms of delirium. The patient may sleep excessively during the day, while at night they may be restless, sleepless or show more pronounced disorientation.
In patients:
- Excessive daytime sleepiness
- Sleeplessness at night
- Reversal of the sleep-wake cycle
- Restlessness at night
görülebilir.
For this reason, there is a close relationship between delirium and Sleep disorders; maintaining a regular sleep rhythm is important both for monitoring the symptoms and for the treatment process.
What Causes Delirium?
Delirium usually does not develop from a single cause. It generally arises when triggering factors such as infection, metabolic disturbance, surgery, drug effects or an intensive care stay are added on top of predisposing factors such as advanced age, existing neurological diseases, use of multiple medications or sensory impairments.
Delirium Due to Infections
Infections are among the most common causes of delirium, especially in elderly individuals.
Infections that pose a risk:
- Urinary tract infections
- Pneumonia
- Sepsis
- COVID-19
- Meningitis
The inflammatory response that occurs during an infection may affect brain function.
Delirium Due to Medication Use
Some medications may cause delirium through their effects on the central nervous system.
In particular:
- Sedative drugs
- Benzodiazepines
- Anticholinergic drugs
- Opioid painkillers
- Some antidepressants
may pose a risk.
In the elderly age group, the use of multiple medications increases this risk.
Delirium Due to Metabolic and Electrolyte Disturbances
Changes in the body's biochemical balance may directly affect brain function.
Examples:
- Hyponatremia
- Hypercalcemia
- Hypoglycemia
- Hyperglycemia
- Uremia
- Liver failure
For this reason, laboratory evaluation is of great importance in patients who develop delirium.
Delirium Due to Neurological Diseases
Some neurological diseases may set the stage for delirium.
These include:
- Stroke
- Brain tumors
- Epilepsy
- Parkinson's disease
- Alzheimer's disease
- Dementia
among others.
In these patient groups, the risk of developing delirium is high because of reduced brain reserve.
Delirium Due to Alcohol and Substance Withdrawal
Sudden discontinuation of long-term alcohol use may cause serious delirium. Delirium tremens, seen especially in people with Alcohol dependence, is characterized by:
- Severe agitation
- Sweating
- Tremor
- Hallucinations
- Changes in consciousness
and requires emergency treatment.
Delirium After Surgery and Anesthesia
The physiological stress response that develops after surgical procedures may cause delirium.
Factors that increase the risk:
- Advanced age
- Cardiac surgery
- Major orthopedic operations
- Prolonged surgery
- Need for intensive care
The frequency of delirium increases markedly, especially in patients treated in Intensive care.
Dehydration, Malnutrition and Vitamin Deficiencies
The brain needs adequate fluid and energy support to function normally.
Conditions that pose a risk:
- Dehydration
- Protein-energy malnutrition
- Vitamin B1 deficiency
- Vitamin B12 deficiency
- Folate deficiency
These conditions should be evaluated carefully, especially in elderly individuals.
Pain, Sleeplessness and Environmental Factors
Prolonged pain and environmental stress factors may also contribute to delirium.
Özellikle:
- Constant loud noise
- The intensive care environment
- Sleep deprivation
- Sensory isolation
- Excessive lighting
may adversely affect brain function.
It should be kept in mind that more than one factor usually plays a role together in the development of delirium. For this reason, comprehensive evaluation, a multidisciplinary approach and in particular the collaboration of the Neurology, Psychiatry and, when necessary, Geriatrics teams are the most important elements that increase treatment success.
Which Diseases Can Cause Delirium?
Delirium is usually not a disease on its own, but a sign of a serious underlying medical condition. For this reason, the primary aim in a patient who develops delirium is to identify the underlying cause affecting brain function. Especially in elderly individuals, infections, organ failure and neurological diseases are among the most common causes of delirium.
Urinary Tract and Respiratory Tract Infections
Urinary tract infections are one of the most common causes of delirium in the elderly age group. In some elderly patients, the classic signs of infection such as fever, burning or pain
may not be present. Instead, the first finding may be a sudden change in consciousness or a behavioral disturbance.
Infections that can cause delirium include:
- Urinary tract infections
- Pneumonia
- Bronchitis
- COVID-19
- Sepsis
among others.
The inflammatory response that occurs during an infection may temporarily disrupt brain function and lead to delirium.
Kidney and Liver Failure
The kidneys and liver play a critical role in removing toxic substances from the body. When the function of these organs is impaired, harmful metabolites accumulating in the blood may affect the central nervous system.
Conditions that pose a risk:
- Chronic kidney failure
- Acute kidney injury
- Uremia
- Liver cirrhosis
- Hepatic encephalopathy
Especially in advanced-stage organ failure, the development of delirium is regarded as a serious clinical warning sign.
Stroke, Epilepsy and Brain Diseases
Diseases that directly affect the brain markedly increase the risk of delirium.
Özellikle:
- Stroke
- Epileptic seizures
- Brain tumors
- Traumatic brain injuries
- Brain hemorrhages
may cause delirium.
Structural or functional changes occurring in brain tissue may affect attention, consciousness and perception processes, leading to an acute confusional state.
Heart and Lung Diseases
Adequate oxygen and blood flow are required for the brain to function healthily.
The amount of oxygen reaching the brain may decrease in the following diseases:
- Heart failure
- Cardiac arrhythmias
- Chronic obstructive pulmonary disease (COPD)
- Acute respiratory failure
- Pulmonary embolism
The hypoxia that develops in these conditions is one of the important causes of delirium.
Meningitis and Encephalitis
Infections of the brain and its membranes are serious diseases requiring emergency intervention.
Infections that may lead to the development of delirium:
- Meningitis
- Viral encephalitis
- Bacterial encephalitis
- Brain abscesses
In these patients, changes in consciousness may often be among the first signs of the disease.
Blood Sugar and Oxygen Level Disturbances
Sudden changes in blood sugar and oxygen levels may directly affect brain function.
Conditions that pose a risk:
- Hypoglycemia
- Hyperglycemia
- Diabetic ketoacidosis
- Hypoxia
- Carbon monoxide poisoning
For this reason, metabolic evaluation is of great importance in sudden changes in consciousness.
What are the Types of Delirium?
Delirium is divided into three main groups according to its clinical presentation. Each type may show different symptoms, and some types may be more challenging to diagnose.
Hyperactive Delirium
It is the most easily recognized type of delirium.
Its symptoms:
- Excessive motor activity
- Restlessness
- Agitation
- Shouting or disruptive behavior
- Tendency toward aggression
- Inability to stay still
These patients are often brought to medical evaluation quickly because of the risk of harming those around them.
Hypoactive Delirium
It is the type of delirium most often overlooked.
Its symptoms:
- Quietness
- Withdrawal
- Excessive sleepiness
- Slow speech
- Reduced attention
- Lack of interest in the surroundings
Patients with hypoactive delirium may often be assessed as tired or depressed. However, this condition can be just as serious as hyperactive delirium.
Mixed-Type Delirium
It is one of the most common types.
Patients:
- May be extremely restless for a period,
- May then become noticeably calmer,
- Symptoms may vary over the course of the day.
For this reason, regular observation of patients is important.
Who is at Higher Risk of Delirium?
Although it can occur in every age group, the risk of developing delirium is markedly higher in some individuals.
Elderly People
As age advances, brain reserve decreases and the body's resilience to stress factors declines.
In individuals over the age of 65:
- Infections
- Fluid loss
- Side effects of medications
- Hospital admissions
increase the risk of delirium.
Patients with Dementia and Alzheimer's Disease
In patients with Dementia and Alzheimer's disease, delirium develops more easily because of the existing reduction in cognitive reserve.
Research shows that the risk of delirium in individuals with dementia is markedly higher than in healthy peers of the same age.
Patients Treated in Intensive Care
Patients treated in Intensive care units carry many risk factors at the same time.
These include:
- Serious infections
- Mechanical ventilation
- Pain
- Use of sedative drugs
- Sleep disorders
can be listed among these.
For this reason, intensive care delirium is now recognized as an important clinical problem.
Patients Undergoing Major Surgery
The risk is high especially after the following operations:
- Heart surgery
- Hip replacement operations
- Major vascular surgery
- Cancer surgery
Surgical trauma and the physiological changes associated with anesthesia may set the stage for delirium.
People Taking Multiple Medications
The use of multiple medications, known as polypharmacy, is an important factor in the development of delirium.
Özellikle:
- Sleeping pills
- Painkillers
- Antidepressants
- Antipsychotics
- Antihistamines
may pose a risk.
People with Vision and Hearing Problems
Reduced sensory input may affect awareness of the surroundings.
For this reason:
- Vision loss
- Hearing loss
- Not using a hearing aid
- Lack of glasses
may increase the risk of delirium.
How is Delirium Recognized in the Elderly?
Early recognition of delirium in elderly individuals can enable life-threatening diseases to be detected in time.
First Signs of Delirium in the Elderly
The first signs may often be mild.
Changes that relatives should watch for:
- Absent-mindedness
- Sudden increase in forgetfulness
- Mixing up names
- Change in sleep pattern
- Restlessness
- Unexplained fears
These signs may become evident within hours.
Why Can Hypoactive Delirium Be Overlooked?
Patients with hypoactive delirium:
- Are quiet,
- Do not complain,
- May appear to be sleeping all the time.
For this reason, it can often be confused with depression, old age or fatigue.
However, research shows that hypoactive delirium may be associated with worse clinical outcomes.
Why is a Sudden Behavioral Change in the Elderly Important?
A behavioral change that develops suddenly in an elderly person should usually not be regarded as normal.
Özellikle:
- Sudden confusion
- Inability to recognize people
- Confusion about place and time
- Changes in speech
may require urgent evaluation.
What is Intensive Care Delirium?
Intensive care delirium is an acute disturbance of consciousness and attention that develops in critically ill patients.
It is seen in a significant proportion of intensive care patients and may directly affect the treatment process.
Causes of Intensive Care Delirium
The main causes:
- Mechanical ventilation
- Sedative drugs
- Pain
- Infections
- Sleep disturbance
- Hypoxia
- Organ failure
can be listed as above.
Symptoms of Intensive Care Delirium
Symptoms that may be seen in intensive care patients:
- Inattention
- Clouding of consciousness
- Inability to recognize the surroundings
- Restlessness
- Hallucinations
- Irregular sleep
are as listed above.
Can Intensive Care Delirium Be Prevented?
Although it cannot always be prevented, the risk can be reduced.
Preventive approaches:
- Early mobilization
- Access to daylight
- Reducing unnecessary sedation
- Pain control
- Adequate fluid support
- An appropriate sleep routine
can be listed as above.
What is Postoperative Delirium?
Postoperative delirium is an acute disturbance of consciousness and attention that occurs after a surgical procedure.
It is regarded as an important complication, especially in elderly patients.
What Causes Postoperative Delirium?
More than one factor may be involved:
- Anesthetic drugs
- Surgical stress response
- Pain
- Blood loss
- Electrolyte disturbances
- Infections
Together, these causes may contribute to the development of delirium.
How Long Does Postoperative Delirium Last?
Symptoms usually:
- Begin within the first 24–72 hours,
- May last a few days,
- May extend to weeks in some patients.
The duration depends largely on the correction of the underlying cause.
In Whom is Postoperative Delirium More Common?
People in the risk group:
- Individuals over the age of 65
- Patients with dementia
- Those who have undergone heart surgery
- Those taking multiple medications
- Those with a previous history of delirium
can be listed as above.
In these patients, a comprehensive preoperative evaluation and close postoperative follow-up are of great importance.
How is Delirium Diagnosed?
No single laboratory test or imaging method is sufficient to diagnose delirium. The diagnosis is made by evaluating together the clinical assessment, the patient's history, the physical examination and investigations aimed at identifying the underlying causes.
Early diagnosis is of critical importance for preventing complications, especially in elderly individuals and hospitalized patients.
Information Obtained from the Patient and Relatives
One of the most important features of delirium is its sudden onset. For this reason, obtaining information about the patient's previous cognitive state is one of the basic steps of the diagnostic process.
The main points the physician asks about are as follows:
- When the symptoms began
- Their variability during the day
- Pre-existing cognitive disorders
- Medications used
- History of alcohol or substance use
- Recent infections or surgeries
Information obtained from relatives is often of diagnostic value.
Physical and Neurological Examination
A detailed systemic and neurological examination should be performed in the evaluation of delirium.
Muayenede özellikle:
- Level of consciousness
- Attention and concentration
- Reflexes
- Motor functions
- Speech skills
- Gait and balance
are evaluated.
When necessary, joint evaluation by Neurology and Psychiatry specialists increases diagnostic accuracy.
Blood and Urine Tests
Laboratory tests play an important role in identifying the underlying cause.
Tests that are frequently requested:
- Complete blood count
- Electrolyte levels
- Kidney function tests
- Liver function tests
- Blood sugar measurement
- Thyroid function tests
- Vitamin levels
- Urinalysis and urine culture
These tests help detect infections, metabolic disturbances and organ failure.
Brain Imaging Methods
In some cases, brain imaging methods may be necessary.
Özellikle:
- Suspected stroke
- Brain hemorrhage
- History of trauma
- Possibility of a brain tumor
- Neurological examination findings
imaging is performed when these are present.
Methods used:
- Computed tomography (CT)
- Magnetic resonance imaging (MRI)
can be listed as above.
Delirium Assessment Scales
Various assessment tools that make it easier to recognize delirium are used in clinical practice.
The most widely used scales:
- CAM (Confusion Assessment Method)
- CAM-ICU
- CDSC (Intensive Care Delirium Screening Checklist)
- 4AT Deliryum Tarama Testi
These scales are important for early diagnosis, especially in intensive care and hospital settings.
What are the Differences Between Delirium and Dementia?
Delirium and Dementia are two different clinical conditions that are often confused with each other. However, there are important differences in terms of onset, course and treatment approach.
Delirium and Dementia in Terms of Onset
Delirium:
- Begins within hours or days.
- Develops suddenly.
Dementia:
- Progresses over months or years.
- Has an insidious onset.
This difference is one of the most important clues in diagnosis.
Delirium and Dementia in Terms of the Course of Symptoms
Symptoms of delirium:
- Vary over the course of the day.
- May worsen especially at night.
In dementia, however, symptoms:
- Progress more steadily.
- Show gradual worsening.
Delirium and Dementia in Terms of Attention and Level of Consciousness
Deliryumda:
- Attention is severely impaired.
- The level of consciousness may change.
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