Neuropsychiatric Symptoms of Dementia in the Elderly
Clinical Overview

Diagnosis and Clinical Differentiation

Definition of BPSD Reversible Causes
Coexisting States Summary

Coexisting States

Both dementia and delirium involve cognitive changes that represent a decline from a previous level of functioning. Both conditions may involve serious behavioral changes as well. Delirium can be, and often is, superimposed on dementia. In fact, an underlying dementia is a significant risk factor for the development of delirium. It is important to note the differences between the two conditions in order to properly manage them.

Depression and dementia may coexist, further complicating the clinical picture. Several different scenarios may be responsible:

The dementia and depression may be due to separate causes (a patient with Alzheimer's disease who develops hypothyroidism which presents as depression)

It is important to note, that because of the overlap in symptomatology between depression and dementia, it may be difficult to distinguish between the two conditions in some patients, especially when delirium is superimposed on dementia. It is suggested that when the diagnosis of dementia is suspected, the patient should undergo an assessment for depression. Similarly, dementia should be considered when depression is diagnosed or suspected in an older adult.

When an elderly individual presents with neuropsychiatric symptoms, the cause is oftentimes due to a medical or metabolic disorder, mood disorder, or probable dementia. There is significant overlap in the symptomatology of these conditions, and, as stated previously, they may coexist.

Typically, the onset of delirium is rapid occurring over a few hours or days, and the onset can be assigned a fairly precise time. The first symptom of delirium is generally that the patient will misidentify the 'unfamiliar' as 'familiar'. For instance, they may relate to a nurse as a daughter, niece, and so on. A delirious person may also have impairment of recent memory (the hallmark sign of Alzheimer's disease). It is important to remember that a change in mental status is very often the presenting symptom of systemic disease. Although, it is generally assumed that symptoms of delirium resolve within one to two weeks after the underlying problem is detected and treated, there are reports of acute delirious episodes lasting for up to a month.

In delirium, the patient exhibits concurrent disturbances in attention, sleep/wake cycle, and psychomotor behavior. This means that the patient may be awake when they should be asleep, asleep when they should be awake, or may be unarousable at times only to be agitated hours later. Symptoms of delirium are highly variable and intermittent with different behaviors being exhibited over a brief span of time. Disorientation is apparent from the onset, as well as perceptual disturbances such as illusions, delusions, and hallucinations. Behavioral symptoms associated with delirium or dementia are often worse at night, an occurrence termed as "sundowning".

The delirious person has widely fluctuating cognitive function and has great difficulty maintaining attention and focusing concentration. Thinking ability, as well as affect are variable from minute to minute, and hour to hour.

Physiologic signs such as sweating and tachycardia are common in delirium, while these changes are typically absent in persons with dementia or depression.

An insidious, slowly progressive course is consistent with a degenerative process like Alzheimer's disease. Memory loss is generally the first detectable symptom. The clinical course of dementia is generally very gradual, occurring over a period of years.

A person with dementia does not exhibit the clouded and fluctuating consciousness seen with delirium. The person with dementia is generally quite alert, and the psychotic disturbances of delusions and hallucinations usually appear late in the course, although some patients exhibit these disturbances in earlier stages.

Again, it is important to emphasize that while many of the signs and symptoms of delirium and dementia may overlap, it is imperative to defer the diagnosis of dementia until delirium has been ruled out.

Depression posing as dementia is common in elderly individuals, presenting with symptoms of a recent cognitive decline. In contrast to Alzheimer's disease where short-term memory loss occurs as a cardinal first sign, all memory is affected equally in the depressed individual. If depression and dementia are coexisting states, the time of onset of depression may help to pinpoint the etiology of the disorder. For instance, depression caused by the Alzheimer's disease patient being aware of failing cognitive decline would occur after the onset of memory deficits. A sudden onset of both dementia and depression may signal a cerebral vascular accident.

Depression does quite often present with somatic complaints. Elderly depressed individuals will very often deny feeling depressed, but will complain about aches and pains.

The Yesavage Geriatric Depression Scale has been shown to be a valid screening instrument for depression in hospitalized and ambulatory elderly patients. The Folstein Mini-Mental State Examination (MMSE) is a useful tool in assessing cognitive deficits. When depressed patients are given the exam, they tend to give "I don't know" answers to questions. In contrast, a patient with Alzheimer's dementia will typically try hard to answer the questions and often will give "near miss" types of answers. While a patient with dementia typically will deny having memory problems, a depressed patient will often complain about their memory deficits and worry about dementia.

Feature Delirium Alzheimer's Dementia Depression
Onset Sudden Insidious Recent
Initial Symptoms Identifying 'unfamiliar' as 'familiar', short-term memory loss Short-term memory loss May present as somatic complaints, all memory affected equally
Duration Hours to weeks Months to years Variable
Alertness Clouded and fluctuating Usually normal until terminal phase Diminished ability to concentrate and communicate
Disorientation From onset Occurs late in course Orientation intact
Hallucinations Common from onset Generally occur late in course In psychotic depression
Cognition Thinking ability highly variable Thinking ability stable, Varies, "I don't know" answers to questions.
Affect Variable Labile. Mood is unstable Flat. Depressed mood is fairly stable
Memory Temporarily affected Depression may occur after memory loss Depression occurs before memory loss
Reversibility? Usually completely reversible Nonreversible and progressive Usually reversible

Selected References

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