Phenomenological Psychology

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What Is the Difference between Delirium and Dementia?

June 15th, 2009 by David Kronemyer · 6 Comments

Both delirium and dementia refer to a state of fundamental mental bewilderment or confusion. There is considerable overlap of symptoms. They primarily involve cognitive dysfunction and include confusion, memory loss, disorganized thinking, spatio-temporal disorientation, flat affect, reduced attention span and loss of motor skills. Patients also tend to have the same types of behavioral problems or issues including sleep disorders, purposeless activity and conduct that is inappropriate or even aggressive. Patients with dementia are at increased risk for delirium.

Symptomatology. Their precise symptomatology is different. Delirium is characterized by acute disturbances of consciousness and global changes in cognition. The patient may be hyperactive if agitated or hyperalert in which case the patient likely will experience disorientation, delusions or hallucinations. The patient may be hypoactive if the patient is lethargic, confused or sedated. Dementia on the other hand is characterized by slower-moving cognitive deficits that include impairment in memory (short term and long-term) and at least one other cognitive disturbance such as aphasia, apraxia, agnosia or disturbed executive functioning. It must cause significant impairment in social or occupational functioning and represent a significant decline from a previous level of functioning.

Course of illness is different. Delirium is transitory. It has quick onset and its symptoms will remit on treatment. Its course is a sudden drop-off from (or reascension to) baseline. Dementia on the other hand is long-term and slow progressing, characterized by a gradual onset decline from baseline. It is progressive, chronic and irreversible.

Etiology is different. Delirium typically is caused by a physiological problem such as substance abuse, metabolic imbalance, liver failure, infection or congestive heart failure. Neurochemically these are related to changes in acetylcholine levels. Dementia on the other hand is caused by neurological degeneration including Alzheimer’s and other neurodegenerative diseases.

Treatment is different. The symptoms of delirium can be reversed or prevented, abating further cognitive or medical impairment. Non-pharmacologic management can include steps such as providing for a quiet, optimized environment. Pharmacologic intervention includes use of neuroleptics such as haloperidol or risperdone (if the patient is agitated or has hallucinations or delusions) or a benzodiazepine if delirium is secondary to substance withdrawal.

The symptoms of dementia on the other hand can be managed but not remitted. Pharmacologic interventions include acetylcholinesterase (AChE) inhibitors such as tacrine, donepezil hydrochloride, rivastigmine tartrate and galantamine hydrochloride; N-methyl-D-aspartate (NMDA) receptor antagonists such as memantine or others; and behavioral medications (antipsychotics, antidepressants, mood stabilizers). The most common drug prescribed for Alzheimer’s is donepezil (Aricept), although its useful life is only approximately six months.