Differentiating Delirium Versus Dementia in Older Adults

Excerpt

Altered mental status is one of the most common presenting complaints in older adult patients and is often related to "3 Ds": delirium, dementia, and depression. Out of the 3 Ds, delirium and dementia are more commonly encountered in clinical practice. The 2 terms are frequently used interchangeably and, therefore, unrecognized during the initial assessment. Understanding that delirium and dementia are distinct syndromes with different prognoses and management is essential, though distinguishing between both diagnoses in the clinical setting can be difficult, even for experienced clinicians. While an acute confusional state that fluctuates and develops over days to weeks is likely to be delirium, a more persistent and chronic progression is more suggestive of dementia; however, these clinical features may not be as evident in patients with underlying dementia who develop acute delirium. Additionally, this distinction is blurred in cases of persistent delirium and reversible dementia etiologies. Cognition is assessed in 6 domains: memory and learning, language, executive functioning, complex attention, perceptual-motor, and social cognition.

Delirium is characterized by an altered awareness mainly affecting attention, whereas dementia is defined as cognitive decline, which interferes with 1 or more domains. Delirium is an abrupt onset of reduced orientation or awareness of the environment in contrast to dementia, a gradual process leading to disturbance in the core features, with attention being affected much later in the disease course.

Typically, dementia is a neurodegenerative disorder seen in older age and is of various subtypes, with the age of onset depending on the subtype. On the other hand, delirium is an age-independent process that occurs more commonly in older adult patients and can happen under variable circumstances. Delirium typically occurs from hours to days, whereas dementia is a slow progressive course over months to years. Delirium and dementia commonly coexist, with preexisting dementia being a leading risk factor for delirium. Sometimes, when dementia is rapidly progressive, it can be challenging to differentiate between the conditions in patients without a prior history of dementia. Therefore, distinguishing between these conditions or identifying superimposed delirium in a preexisting dementia patient is essential, as misdiagnosis may lead to a prolonged hospital stay, accelerated cognitive and functional decline, increased healthcare costs, and even death.