Delirium, Dementia and Depression

The three Ds-delirium, dementia and depression-are disorders often confused by caregivers as they are complex and patients can be afflicted with more than one of the conditions at the same time.

Although often coinciding, the three Ds are entirely separate conditions.

Delirium is an acute but reversible state of confusion occurring in up to 50% of older post-surgical patients.1

Dementia is an irreversible decline of mental abilities which affects 5-10% of the U.S. population over age 65, with incidence doubling every 5 years after 65.2

Depression is a mood disorder which affects 16% of the population, although it often is unrecognized.2

Similarities & Differences

Because delirium and dementia are cognitive disorders with impaired memory, thinking and reasoning, they can have devastating effects on the ability to function in daily life.3

Depression meanwhile, can also affect concentration and judgment, and so symptoms can mimic a cognitive disorder 4 Dementia is differentiated from pseudodementia (depression) in the elderly. Pseudodementia is defined as depression with cognitive impairments.5

Careful history taking and evaluation of the onset is the key.

Acute and worsening symptoms at night in an otherwise cognitively healthy person may be indicative of delirium, whereas dementia is usually insidious; depression may be worse in morning after the person has had difficulty sleeping.

Medical evaluation should include brain imaging; lab work to evaluate metabolic, endocrine or infectious processes; or toxicology. A mental status exam and neuropsychological testing can evaluate cognition and determine insidious problems one may not be aware of.

Some examples of Psychological Assessment Tools for these disorders are outlined in Table 1.

TABLE 1: Tools for Diagnosing the Three Ds2

Delirium Tools

Dementia Tools

Depression Tools

Delirium Symptom Interview

Global Deterioration Scale

Geriatric Depression Scale

NEECHAM Confusion Scale

Alzheimer Assessment Scale

Beck Depression Inventory

Diagnosing Delirium

A 78-year-old woman who was awake, alert and oriented becomes confused, combative and paranoid following hip surgery. She is frightened, agitated, fighting with the staff and attempting to get out of bed. As one of her healthcare providers, you are concerned for her safety and start to wonder if she has underlying dementia. But all of the signs and symptoms point to delirium, so you notify the physician. In the morning, she is much more coherent-when the physician makes his rounds, of course.

Delirium is often unrecognized or misdiagnosed and commonly mistaken for dementia, depression, mania, an acute schizophrenic reaction, or part of old age.

The prevalence of delirium ranges from 10-30% in med/surg patients, and among elderly inpatients it can be as high as 50%.

The physiologic causes of delirium are often: infection, hypoxia, hypoglycemia, and hyperthermia. Hyperthermia can happen easily in an elderly person gardening in the summer out in the sun, as the elderly have a decreased thirst mechanism and can quickly have a change in mental status with dehydration and hyperthermia.

Patients are often admitted to hospitals due to a change in mental status as a result of a UTI or pneumonia. Of course, cerebral meningitis, encephalitis and syphilis can also cause delirium.

Drug-related delirium is seen with: substance intoxication or withdrawal; anticholinergic use; and use of high doses of prednisone which can cause prednisone psychosis. Similarly, one can have reactions to anesthesia or prescribed medicines.3

Delirium is a disturbance in consciousness; develops rapidly; often occurs with a change in cognition; and may be accompanied by illusions, visual hallucinations, sleep and sensory disturbances. The causes of delirium are physiologic (metabolic), infection or drug related.3 However, many cases of delirium have an unknown cause. Sensory or sleep deprivation and change of environment can result in delirium.3

Some diagnostic features of delirium are:

  • limited attention span;
  • disorientation to time and place (not person);
  • fluctuating levels of awareness ranging from alertness to stupor;
  • global cerebral dysfunction;
  • confusion; and
  • short-term memory loss.

    All of these can be confused with dementia, while delusions, illusions or hallucinations are often misdiagnosed as acute psychosis.

    At times, the two diagnoses of delirium and dementia co-exist. However, the symptoms of delirium are often short lived (once the cause is successfully treated), so dementia will remain after the delirium has cleared.

    Recognizing Dementia

    An 83-year-old man who is admitted for cellulitis has difficulty remembering why he is in the hospital, and is getting increasingly anxious. As it gets later in the day, he develops a fever and starts to get increasingly confused and agitated. Now, the patient has signs and symptoms of both delirium and dementia, resulting in some confusion among clinical staff.

    The most common disease associated with dementia is Alzheimers, which accounts for 60-80% of cases.4

    The most prominent feature of dementia is memory impairment and the patient is fully alert, whereas, in delirium this is often impaired. Along with memory deficits, there are difficulties with problem solving, judgment and ability to sequence events.

    As the disease progresses, the patient has increased difficulties with the 4 As: amnesia (retrograde), aphasia (expressive and receptive), apraxia (the ability to replicate motor activities) and agnosia (the ability to recognize).4

    There are 7 stages culminating in severe decline, which typically happens over 8-20 years.4

    A medical assessment may also reveal:

  • poor judgment;
  • disorientation;
  • illusions and confusion;
  • confabulation, i.e., tells stories to fill in memory gaps;
  • lability;
  • quarrelsome/angry;
  • depressed and withdrawn; and
  • poor memory that continues to decline.

    Dealing With Depression

    A 69-year-old male is admitted to the hospital for asthma. He has a poor appetite and memory, sad mood and affect, is reluctant to perform self-care and has reversed sleep-wake cycles.

    Medical interventions for depression include providing safety; promoting a therapeutic relationship; promote and/or assist with ADLs; communicate therapeutically; evaluate effectiveness of medications; and educating about illness and medications. Intervention should also include assessing patients diagnosed with depression for suicidal ideation and plan of action. Providers can contract with the patient to inform staff when feeling suicidal and/or place the patient on suicide watch.

    It is important to note that when patient feels better he or she may be at increased risk for suicide, because they have more energy and may be more at peace having made a decision to end their life.

    Assessment for depression can include:

  • General Appearance: sad, psychomotor retardation or agitation.
  • Mood & Affect: sad, hopeless, helpless, inability to feel pleasure, low-self esteem.
  • Thought Process & Content: slowed thinking; negative/pessimistic; makes self-deprecating remarks; ruminates; may have thoughts of dying/committing suicide.
  • Sensory and Intellectual Process: may/may not be oriented; memory impairment; difficulty concentrating.
  • Judgment & Insight: impaired judgment and difficulty with decision making; insight may/may not be impaired.
  • Physiologic & Self-Care: weight loss; sleep disturbance; loss of interest in sex; neglect personal hygiene; may have many physical complaints including pain or mobility problems.
  • Risk for suicide: anxiety; ineffective coping; hopelessness; impaired social interaction.

    The disorders of delirium, dementia and depression are often misdiagnosed and at times patients present with two of the disorders and it is difficult for providers to evaluate and intervene in their care. However, developing an understanding of these separate but often interrelated disorders can improve providers’ ability to care for this population.

    Victoria Siegel is associate professor at Suffolk County Community College in Long Island, NY.

    1. Cole, M.G., et al. (2008) Delirium in older patients: clinical presentation and diagnosis.
    3. Townsend, M. (2011). Essentials of psychiatric mental health nursing: concepts of care in evidenced-based practice. (5th ed.) pp. 223-260. F.A. Davis: Philadelphia
    5. Arch Gen Psychiatry. 2006; 63(3):273-279. doi:10.1001/archpsyc.63.3.273


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