Diagnosis & Tests

Healthcare professionals pay special attention to changes from a older adult’s usual mental state, while taking into consideration any physical problems. For example, when speaking to the older adult, they may notice that the patient’s attention wanders, that they are restless, distracted easily and unable to follow directions, or that their speech is disorganized and doesn’t make sense. 

A diagnosis of delirium is made on the basis of careful observation and, mental status testing. To evaluate thinking and specifically someone’s attention span, doctors may use a simple set of tests and standardized questions similar to those used to diagnose dementia. These are examples of typical questions:  

  • Perform a simple math calculation
  • Spell a short word backward
  • Repeat a series of four or five numbers, in order and then in reverse order
  • Name the days of the week backward

Other tests to assess cognitive health include the Mini–Mental State Examination (MMSE), the Confusion Assessment Method (CAM), and other similar tests. Since many subtle or hypoactive cases of delirium are missed, healthcare professionals need to check the cognitive health of every older hospitalized patient. If you think that delirium may be present in a family member or someone close to you, you must alert a healthcare professional and have the person evaluated.

When the causes of delirium are not clear, the healthcare provider must take a complete history and perform a physical exam. The history will include a review of all medications being taken, including over-the-counter medications and herbal remedies. Blood tests and other studies may also be appropriate.

The following tests may be used by healthcare professionals to determine causes of delirium:

  • Neurological exams, including tests of feeling (sensation), thinking (cognitive function), and motor function
  • Psychological tests evaluating for depression or acute psychiatric syndromes
  • Blood tests (such as a comprehensive metabolic panel or toxicology screen)

Other tests based on the person’s symptoms may include:

  • Chest x-ray
  • Urinalysis 
  • Electrocardiogram
  • Cerebrospinal fluid test
  • Electroencephalogram (EEG)
  • CT or MRI scans of the head

Differentiating Delirium from Look-Alike Conditions

Delirium can be mistaken for dementia or for psychiatric diseases such as schizophrenia. Hypoactive delirium is often confused with depression. Certain rare forms of epilepsy can also closely resemble delirium. However, in epilepsy there is usually a history of seizures before the episode of sudden confusion.

Different characteristics of dementia and delirium

Delirium and dementia share several characteristics that often make it hard to tell them apart. For example, both syndromes involve memory loss and language difficulties. Also, since dementia greatly increases the risk of delirium, they can exist at the same time.

Slow onset over months to years; remains a long-term condition Sudden onset over hours to days; lasts a shorter length of time
Normal speech Slurred speech
Conscious and attentive until late stages; status relatively stable In and out of consciousness; inattentive, easily distracted; decreased attention and environmental awareness; symptoms variable, disappearing and reappearing rapidly
Hallucinations possible Hallucinations common (usually visual)
Listless or apathetic mood most common; agitation possible Can be anxious, fearful, suspicious, agitated, apathetic, disoriented, having disorganized thinking, listless, unaware
Often no other sign of physical or medical illness Other signs of illness are common (fever, chills, pain) or drug side effects
Delirium occurs very often in older people suffering from dementia, but it is a distinct syndrome requiring medical attention.

Differences between delirium and psychiatric conditions

The best way to differentiate delirium from psychiatric problems is by considering age and how suddenly the symptoms appeared. If an older person's behavior changes suddenly, you should consider delirium as a possibility. Other features that may help separate psychiatric disease from delirium are the types of hallucinations that the person experiences. People with psychosis typically hear voices or sounds, while people with delirium usually have visual hallucinations, seeing things that aren’t really there. Certain physical characteristics – for example, hand-flapping and EEG changes – are typical of delirium. Sudden underlying medical illness is also unusual in psychiatric disorders.


Last Updated July 2020

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