First, the definitions: Delirium is a short-lived, usually reversible clouding of the consciousness which develops rapidly, is accompanied by agitation or stupor, and is commonly seen in medical wards of general hospitals. For the patient, it is a dream-like experience. By contrast, dementia is characterized by a gradual decline in cognitive functioning with no impairment in consciousness until late in the course. It develops insidiously over months or years and gets worse over time. Patients tend to end up in nursing homes or psychiatric hospitals. Neither dementia nor delirium is considered a disease, but rather they are manifestations of underlying pathophysiology. (1)
The reason for including both in this article is that they are highly interrelated, although the research on delirium as a complication of dementia is sparse. A recent retrospective analysis of outpatients in a psychiatric hospital’s memory clinic concluded that the frequency of delirium varies with each dementia type. “In addition,” the authors note, “delirium decreases activities of daily living, exaggerates behavioral and psychological symptoms of dementia, and is associated with cerebrovascular disease in patients with neurodegenerative dementias.” Delirium was present in nearly 20% of the 206 cases. (2)
In my personal experience, there were a number of Alzheimer’s patients during my Masters internship in Rehabilitation Counseling in an inpatient psychiatry ward of a large teaching hospital. A couple of these patients had a dual diagnosis of schizophrenia. (When I asked one nurse how she was that morning, she replied, “Always nice to start the day off with brown episodes,” referring to the incontinence both patients suffered.) Another patient, only in her thirties, developed dementia from hepatic encephalopathy as a result of alcoholism. Demented patients, even without complications, may be unconcerned about their psychological deficits, whereas a delirious patient experiences anxiety. Again, from personal experience, I can attest to the highly disturbing effects of delirium brought on by a biochemical imbalance (in my case, hypokalemia, potassium deficiency, caused by dehydration from a colonoscopy prep fluid, called Fleet’s Phospho-Soda, which has since been taken off the market).
Azheimer’s Disease is the most prevalent form of dementia. The second most common type is vascular dementia, which is caused by lack of blood flow to the brain, as can happen after a stroke or just through aging. It can also cause visual disturbances, including hallucinations. Lewy body dementia can also cause halluciinations and, in addition, insomnia, narcolepsy and parkinsonism. Patients may crash into furniture and have violent dreams. Another type is called frontal-temporal, which is characterized by earlier onset, with personality changes more marked than memory problems, compromised insight and impaired executive functions. (3)
What dementia and delirium have in common are deficits in memory and abstract thinking. Also adversely affected is problem-solving and the ability to learn new tasks as well as social, temporal, and geographic orientation. While both are marked by global cognitive impairment, delirium usually presents acutely rather than insidiously, with extreme agitation and disordered thinking. Delirious patients may be jacked or nodding off. They are inattentive, often incoherent and perceptually confused, sometimes to the point of hallucinating. Among the factors to rule out before diagnosing dementia are: mental illness, metabolic/endocrine disorders, trauma, infection, and substance abuse. Elderly people are more prone to become delirious than younger people, and hospitalization itself may be a precipitating factor. Many cases of delirium can be resolved completely when properly treated. It may take hours; it may take weeks. (4)
Dementia in general is characterized by memory deterioration and an increasing inability to manage the personal affairs of daily life. Personality changes are the norm with psychotic often developing later. Early in Alzheimer’s, the memory impairment and other cognitive deficits tend to be mild compared to the changes in behavior. Those afflicted may do things completely out of character and yet have little understanding that they have acted in a socially inappropriate manner. After years of decline, the outcomes are weight loss, incoherence, and inability to walk or dress without assistance. Vacuoles (microscopic holes), amyloid plaques, and neurofibrillary tangles are evident in the brain cells upon autopsy. (5)
These two types of cognitive impairment are discussed here together because despite their seeming distinctiveness from definitions, it is a common dilemma to distinguish them clinically. “The safest clinical approach,” note two experts in geriatric medicine, “is to consider that all older people presenting with confusion have delirium until proven otherwise.” (6) Another source of uncertainty is with presentations that could be dementia or simply depression, or both. There is a syndrome called “pseudodementia” (7) which refers to a situation in which a person with depression also has characteristics resembling those of dementia, but this is a reversible impairment. Successful treatment of the depression will cause the other symptoms to disappear.
– Wm. D., 30 May 2014
References: (1) Robert J. Waldinger (1997). Psychiatry for Medical Students. (2) N. Hasegawa et al (2013). Prevalence of delirium in outpatients with dementia. (3) S. Salloway (2012). http://www.ncbi.nlm.nih.gov/pubmed/22928231 (4) S.B. Guze, Ed. (1997). Washington University Adult Psychiatry. (5) http://www.medscape.org/viewarticle/499458 (6) J. Young, S.K. Inouye (2007). Delirium in older people. (7) M. Fisman (1985). Pseudodementia. http://www.ncbi.nlm.nih.gov/pubmed/3911280.
neuropsychsoc 