Rehan Aziz, MD. Associate program director, Geriatric Psychiatry Fellowship Program, Jersey Shore University Medical Center; associate professor of psychiatry and behavioral science, Hackensack Meridian School of Medicine, Edison, NJ. Dr. Aziz, author of this educational activity, has no relevant financial relationship(s) with ineligible companies to disclose.
Delirium is one of the most perplexing psychiatric findings in older adults. It is defined as a disturbance of attention and a change in cognition. Delirium can be a cause of altered mental status (AMS), which is a general term defined as a change in mental functioning affecting cognition, consciousness (from slight confusion to coma), or both. Delirium affects both cognition and consciousness, whereas dementia affects cognition but preserves consciousness. This article will shed some light on assessing and working up delirium in older adults.
Start by establishing the period over which the symptoms developed. Family and friends are often helpful here. Knowing the episode’s duration can help you narrow down its cause and choose your next course of action.
Delirium occurs over minutes to days. The more acute and rapid the change, the more often it’s life threatening. Subacute AMS happens over weeks to months, while chronic AMS takes place over months to years (Smith AT and Han JH, Semin Neurol 2019;39:5–19). See “Selected Causes of Altered Mental Status” table for potential causes of AMS as well as other important considerations.
Table: Selected Causes of Altered Mental Status
(Click here to view full-sized PDF.)
Predisposing and precipitating risk factors for delirium
Delirium is a relatively common cause of AMS. It is always caused by underlying medical conditions or medications/substances. Typically, there’s more than one cause. It’s important to identify the cause(s) of delirium because correcting the underlying disturbance is the primary treatment. While mental health clinicians may not be responsible for treating core medical illnesses, we often must be the ones to ensure that a complete workup has been done. It’s also within our role to review the medication list and work with other clinicians to taper off problematic drugs.
It’s important to pay attention to risk factors, because reducing them can help prevent or shorten the course of delirium. Predisposing risk factors increase the risk of delirium, while precipitating risk factors trigger delirium. Precipitating risk factors are further separated into acute insults, environmental exposures, and delirium-inducing medications. See “Contributing Causes of Delirium” table.
Table: Contributing Causes of Delirium
(Click to view full-sized PDF.)
Physical/neurological examination—high-yield pearls
A focused physical exam can provide valuable information about the origin of a patient’s AMS.
Look for signs of trauma, which could suggest an intracranial hemorrhage. Battle’s sign (bruising behind the ear) indicates a possible skull base fracture.
Neck stiffness, headache, and photophobia point toward meningitis.
In a study of 201 participants (mean age 84 years, 62% female), if both answers were incorrect, this screen had 93% sensitivity and 64% specificity in picking up AMS (Fick DM et al, J Hosp Med 2015; 10(10):645–650).
Delirium in an older adult is often due to a combination of factors. It’s helpful to tailor your workup by thinking systematically through medical and psychiatric contributors. Assess for medication and substance use by reviewing medication lists (including over-the-counter products), consulting data from prescription drug monitoring programs, checking drug levels, and obtaining alcohol/urine toxicology screens. Other diagnoses to consider include infections, metabolic/electrolyte abnormalities, nutritional deficiencies, non-convulsive status epilepticus, or structural causes.
Several psychiatric disorders can also cause AMS. See “Differential Diagnosis for Confusion” table for three of the most common psychiatric disorders to cause AMS. In addition to these, consider depression, apathy, and catatonia.
Table: Differential Diagnosis for Confusion
(Click to view full-sized PDF.)
Labs and imaging
While it may be tempting to “throw the kitchen sink” at the patient, it’s often better to order a standard workup and add studies as needed. Customary labs include:
In select cases, I might also consider:
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