The Difference Between Dementia and Delirium

Cognitive impairment is more common as we age. Dementia and delirium are two common causes. Delirium and dementia have similarities and can be confusing to experience and to distinguish. Both can cause memory loss, poor judgment, a decreased ability to communicate and impaired functioning. However, there are many differences between the two.

“Dementia resembles delirium in the same way an ultramarathon resembles a dash across the street. Same basic components, vastly different scale.” ~Floyd Skloot

Onset: Dementia typically begins slowly and is gradually noticed over time. If the person who’s being evaluated is unknown to you, having a report of his usual functioning is key. Delirium is usually a sudden or acute change in condition. One day, someone is doing fine, the next, they may be very confused and unable to perform tasks, like dressing.

Cause: Dementia is typically a disease such as Alzheimer’s, vascular dementia, Lewy Body dementia, frontotemporal dementia or a related disorder. Delirium is usually triggered by a specific illness, including: urinary tract infection, pneumonia, dehydration, illicit drug use, or withdrawal from drugs or alcohol. Medication interactions can also cause delirium.

Duration:   Dementia is a progressive, chronic disease that is incurable. Delirium is normally short term and can last for a couple of days to a couple of months. Delirium is almost always temporary if the cause is identified and treated.

Communication Abilities: People with dementia often experience difficulty remembering and finding the right words. Their ability to express themselves erodes over time as the disease progresses. Delirium may cause inappropriate and/or incoherent communication that is uncharacteristic for the individual.

Attention Span and Memory: With dementia a person’s memory is significantly affected throughout the disease. The level of alertness is typically not affected until the late stages of the disease. With delirium, memory functioning is usually less affected, but the general ability to focus and maintain attention is very poor.

Activity Level: Dementia tends to not affect a person’s activity level until the later stages. People with delirium are often overly active (hyper and restless) or under-active (lethargic and less responsive) compared to usual activity.

Treatment: There are a few medications approved by the FDA to treat Alzheimer’s disease, the most common type of dementia. They don’t cure dementia but sometimes can slow the progression of the symptoms, including: memory loss, poor judgment and behavioral changes. Delirium requires immediate treatment by a physician. Because delirium is usually caused by a physical illness or infection, medications are often effective.