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Section 19
Differential Diagnosis in Older Adults: Dementia,
Depression, and Delirium

Question 19 | Test | Table of Contents

Differential Diagnosis
Traditionally, organic mental disorders have been defined as behavioral, cognitive, or emotional impairments that are the result of some physiological dysfunction of the brain (American Psychiatric Association [APA], 1987). The fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; APA, 1994), however, no longer uses the term "organic" because it suggests that other disorders (e.g., bipolar disorder, schizophrenia) do not have an organic contribution (Spitzer, First, Williams, Kendler, Pincus, & Tucker, 1992). Instead, organic mental disorders are referred to as either "secondary disorders," if they are the primary result of an identifiable medical disorder (e.g., stroke, brain tumor), or "substance-induced disorders" (e.g., alcohol dementia, cocaine delirium), if the primary cause is a substance.

Practically any kind of psychological symptom can be caused by a physical condition or a substance (Allen & Blazer, 1991; Conn, 1991). Four basic questions can help to rule out the presence of an underlying physical condition. First, are the psychological symptoms accompanied by any unexplained physical problems? For example, late-onset diabetes (Type II) initially presents with depression and loss of energy, but there are also concomitant weight loss and thirst cravings (Vickers, 1988). Second, could the psychological symptoms be due to an identified chronic disorder that is worsening? For example, cardiovascular and respiratory diseases can progress to the point that oxygenation of the brain is impaired, resulting in symptoms such as confusion, hallucinations, and dulled mental abilities (Lindesay, Macdonald, & Starke, 1990). Third, could prescription drugs, over the counter medications, or other substances be causing the symptoms? It is important to consider new medications in their own right as well as their interactive affects with other drugs that are being taken. Fourth, are there any cognitive impairments? Both delirium and dementia present with marked cognitive impairment, especially in attention and memory.

Delirium
In DSM-IV (APA, 1994) the primary feature of delirium is reduced consciousness (e.g., difficulty staying awake) as well as reduced ability to maintain, focus, and shift attention to outside stimuli (e.g., questions must be repeated). DSM-IV also requires at least one other symptom of cognitive disturbance, such as memory problems, disorientation, language disturbance, or of perceptual disturbance (e.g., objects appearing smaller than normal). Frequently there are diurnal variations in symptoms. Nights may be characterized by more confusion and wakefulness, and days may contain pronounced drowsiness, although there can be periods of clarity (especially in the morning; Lindesay et al., 1990). Symptoms typically develop rapidly over hours to days, with total duration rarely lasting as long as a month.

Delirium is common after the age of 60 (Conn, 1991). This is primarily due to increased vulnerability to disease and changes in the body's ability to metabolize drugs. As a result, states of delirium can be triggered by infections, cardiac failure, strokes, fluid electrolyte disturbances (e.g., dehydration), metabolic disturbances (e.g., hypo-glycemia, vitamin B deficiency), and postoperative states (APA, 1994). About 40% of the cases are due to direct or indirect effects of medications (Lindesay et al., 1990). Although many drugs can induce delirium, medications that are particularly likely include psychotropics (especially benzodiazepines, phenothiazines, and tricyclic antidepressants), antihypertensive agents (e.g., diuretics, beta-blockers), and antiparkinsonian agents such as levodopa (Conn, 1991; Lindesay et al., 1990). Penicillin, taken over a long period of time, can also cause delirium (Conn, 1991). The suspicion of delirium should be considered a medical emergency (Francis et at., 1990). Untreated, one in four individuals will die within I month (Lindesay et al., 1990).

It should be noted that older adults are particularly prone to developing delirium as the result of either using or withdrawing from a drug (Schuckit, 1990). This is due to age-related changes in the body's ability to metabolize and distribute a drug. As a result, the development of delirium is more frequent during conditions such as alcohol withdrawal (Miller, 1991).

Assessment includes a careful review of the medical history, interviews with the client and knowledgeable family members, and screening for cognitive impairment. Because clients may not be able to accurately describe their symptoms, family members can be queried about medical issues (e.g., medication changes) as well as the recency of behavioral and cognitive impairments. In terms of screening questions, the Mini-Mental Status Exam (MMSE; Folstein, Folstein, & McHugh, 1975) is the most widely used screening instrument for differentiating organic and functional mental disorders (Tombaugh & McIntyre, 1992). Although it only takes 5-10 minutes to administer, MMSE assesses orientation, memory, attention, concentration, language, and visual-motor ability. Finally, particular mental status questions can be quite useful. These include asking the client to repeat a series of digits forward (attention), recall three words after 5 minutes (short-term memory), and draw a clock (visual-motor; Lindesay el. al, 1990; Mungas, 1991). Attention and degree of consciousness can be further assessed by asking the client to indicate each time the letter A is said in a series of 15 or so random letters.

In terms of differential diagnosis, delirium is most often confused with dementia or an acute psychosis (APA, 1994; Conn, 1991). Differentiating delirium and dementia is particularly difficult because about a quarter of those who present with delirium have a preexisting dementia (Conn, 1991; Lindesay et al., 1990). Dementia caused by Alzheimer's disease (AD) can be distinguished by the chronicity of symptoms over months to years, the lack of sudden worsening of symptoms, less diurnal variation, and better performance on attention tasks (APA, 1994; Conn, 1991). Dementia due to small strokes--termed multi-infarct dementia in DSM-III-R and vascular dementia in DSM-IV shows more circumscribed impairment (e.g., memory, aphasia), and alertness and attention are typically intact (Cummings & Benson, 1.983). In differentiating psychotic disorders from delirium, the former are more likely to be characterized by a prior psychiatric history, systematized (versus fleeting) delusions, and less pervasive cognitive impairment (Conn, 1991).

Dementia
The cardinal features of dementia are multiple cognitive problems that include memory impairment (short- or long-term) along with at least one of the following cognitive disturbances: language disturbance (aphasia), inability to carry out sequential motor activities (apraxia), failure to recognize familiar objects (agnosia), and disturbance in higher cognitive functions (e.g., abstract thinking, planning, organizing; APA, 1994). In clients younger than 50 years of age, the most common causes of dementia are alcoholism and AIDS. After the age of 50, there is a sharp increase in incidence, with 60% of the cases being due to AD and 20% being the result of strokes due to cerebrovascular disease (Cummings & Benson, 1983; Read, 1991).

In the remaining 20% of older persons with dementia, the cause is another physical disorder such as a metabolic disturbance (e.g., hypothyroidism, kidney disease), a vitamin deficiency (especially the B vitamins), Parkinson's disease, excess fluid in the brain (hydrocephalus), alcoholism, or prescription drugs. The most commonly used medications that can cause dementia include psychotropics (especially lithium, tricyclic antidepressants, benzodiazepines, and phenothiazines), antihypertensives (e.g., methyldopa, clonidine, diuretics), anticancer medications, and antibiotics (Cummings & Benson, 1983; Hinrichsen, 1990; Salzman & Nevis-Owen, 1992). These medications can impair cognitive abilities by either toxicity effects or alterations in other bodily systems that effect mental functioning. For example, elderly people are particularly sensitive to the side-effects of drugs like phenothiazines (e.g., prolixin) and trycyclic antidepressants because they can disrupt cholinergic synaptic functioning in the brain and cause memory as well as other cognitive impairments (Cummings & Benson, 1983; Salzman & Nevis-Owen, 1992). While AD and cerebrovascular disease cause irreversible cognitive impairment, dementia caused by many of the other medical disorders can be reversed if treatment is initiated promptly (Brock & Simpson, 1990; Read, 1991).

The pattern of symptoms can help to differentiate the different types of dementia as well as the degree of progression. In AD, memory disturbance is the hallmark feature. During the first phase of the disorder, short-term memory is impaired followed by problems with long-term memory (Cummings & Benson, 1983). The individual may forget things like turning off the oven or completing a task if interrupted. Expressive aphasia may begin to manifest itself in the form of word finding problems. The individual may get lost or become disoriented in unfamiliar surroundings. In the second phase of AD, further cognitive impairment becomes evident in the form of agnosia and apraxia. Language expression and comprehension worsens to the point that coherent conversation becomes difficult. Personality is frequently characterized by indifference and apathy (Benson & Cummings, 1986). Skills needed to live independently (e.g., cooking, cleaning, managing money) become impaired as well as some basic living skills such as grooming and bathing. In the last phase of AD, cognitive abilities worsen to the point that higher intellectual abilities and self-care skills disappear altogether (Cummings & Benson, 1983).

Vascular dementia, the second most common type of dementia, has a number of characteristic features that can help to differentiate it from AD (Benson & Cummings, 1986; Hinrichsen, 1990; Read, 1991). In vascular dementia, the individual loses some cognitive ability as a result of a small stroke or series of strokes. Although cognitive loss in AD is slow and progressive (over months to years), impairment occurs more abruptly in vascular dementia (from hours to days). A family member might report, for example, that her father suddenly has more word finding problems or is more forgetful. Other aspects of behavior such as the ability to use a computer may be unimpaired. A few months later another abrupt decline in cognitive functioning may occur with deterioration showing this stepwise decline over time. Another difference is that vascular dementia frequently presents with soft neurological signs such as slight weakness in one hand, difficulty pronouncing words, or difficulty swallowing (APA, 1994). It should be considered whenever the client either has had a history of a stroke or has risk factors such as hypertension, smoking, atherosclerosis, or diabetes (Benson & Cummings, 1986).

Metabolic disorders and disorders like Parkinson's disease and Huntington's disease can cause somewhat different patterns of symptoms in dementia. First, these disorders do not typically produce aphasia in contrast to either vascular dementia or AD (Cummings & Benson, 1983). Second, memory problems in these disorders are not as pervasive as in AD. Third, the clinical picture tends to be dominated by symptoms such as depressed affect, slowed thinking, and movement disturbances such as facial grimacing, tremors, and rigidity (Read, 1991).

The diagnostic picture is complicated by the fact that depression, psychosis, or delirium can be a secondary feature in most types of dementia (APA, 1994; Lindesay et al., 1990). For example, about a third of those who develop AD or vascular dementia will also have a secondary depression or psychosis that seems to be organic in nature (Jeste & Krull, 1991; Read, 1991; Rovner; 1992). In terms of differential diagnosis, secondary psychosis tends to be characterized by nonelaborated delusions (e.g., "Someone is stealing my things") or simple hallucinations (Jeste & Krull, 1991). Systematized delusions (e.g., elaborate plots), ideas of reference, and thought insertion are more characteristic of a functional psychosis like schizophrenia.

A number of assessment instruments have been found to be particularly useful in the diagnostic process (Fields, 1991; Hinkle, 1990; Mungas, 1991). First, benign forgetfulness can be differentiated from early dementia by scores of 25 and above on the MMSE, good performance on in-office memory tasks, and a pattern of forgetfulness that is characterized by forgetting aspects of an event versus the event itself (Addonizio & Shamoian, 1986). Those who have dementia, however, will score below 20 on the MMSE and show impairment in mental status areas such as memory, abstraction, and figure drawing (Mungas, 1991). Furthermore, depending on how far the dementia has progressed, there also may be deficits in self-care skills such as shopping or cooking. In this regard, a number of scales are available that assess the client's functioning across a range of living skills (Blessed, Tomilson, & Roth, 1968; Fillenbaum, 1985; Pfeiffer, Johnson, & Chiofolo, 1981).

Depression
 Up to the age of 75 years, depression is the most common mental disorder (Allen & Blazer, 1991). Ironically, however, it is probably the most overlooked disorder in older adults (Mungas, 1991; Rapp, Parisi, & Walsh, 1988; Small, 1991). Two major factors contribute to the low detection rate. First, common symptoms of depression, such as depressed mood and guilt, become less prominent with age, but somatic symptoms (e.g., disturbances in sleep, appetite, and energy) become more apparent (Allen & Blazer, 1991; NIH, 1992). The absence of depressed mood may mislead the diagnostician into believing that symptoms are due to a physical condition. Also, older adults may be more comfortable asking for medical rather than psychological help and like the diagnostician, may be unaware that their symptoms are indicative of depression (Koenig, Meador, Cohen, & Blazer, 1992; Myers, 1990).

The major diagnostic categories to consider with depression include major depressive disorder, dysthymia, adjustment disorder with depressed mood, and bereavement. In addition, physical factors such as disease or medications can cause an organic depression (Allen & Blazer, 1991).

Bereavement.Bereavement is the normal reaction to the death of a loved one and may include a number of depressive symptoms (APA, 1994). But what are signs that bereavement has become complicated by a more serious condition, like major depression? A depressive disorder may be present if the clinical picture is dominated by symptoms such as worthlessness, suicidal preoccupation, excessive guilt, hallucinatory experiences, and psychomotor retardation (APA, 1994; Brock & Simpson, 1990). Too, there may be a great deal of impairment in social functioning (e.g., client avoids people altogether) or occupational endeavors (e.g., client is unable to work). In assessing the severity of the reaction, the counselor should consider the time since the loss, the length of impairment, and cultural differences that might moderate the mode of grieving. In DSM-IV (APA, 1994) a major depressive disorder can be diagnosed if numerous depressive symptoms persist beyond 2 months after the loss.

Adjustment disorder.Adjustment disorder with depressed mood entails a maladaptive reaction to a stressor that manifests itself in either moderate symptoms or moderate impairment in social, inter-personal, or occupational functioning (APA, 1994). According to DSM-IV (APA, 1994), symptoms should only persist for 6 months after the termination of the stressor or its consequences. For example, retirement might trigger depressed mood, a sense of worthlessness, and loss of energy that persists for 5 months. There is some evidence that older adults react to stress with depression, whereas younger adults are more likely to become aroused and anxious (Allen & Blazer, 1991; Gintner, Hollandsworth, & Intrieri, 1986). The clinician should rule out a major depressive disorder and dysthymia when examining symptom severity and duration.

Dysthymia.In DSM-IV (APA, 1994) dysthymia is characterized by the presence of depressed mood plus two other depressive symptoms that persist for at least 2 years. In elderly people, it is not uncommon for dysthymia to be triggered by chronic illness, functional loss, social isolation, or a complicated bereavement reaction. The principal differential diagnosis is with a major depressive disorder that can mimic dysthymia by peaking early over a 2-year period and slowly dissipating over time.

In older adults, however, chronic symptoms such as fatigue, low energy, and appetite disturbance can also be due to chronic illnesses, medications, or alcohol use (Allen & Blazer, 1991; Small, 1991). Chronic illnesses that may produce dysthymia-like symptoms include endocrine disorders (e.g., hypothyroidism, diabetes), infections (e.g., Epstein-Barr), strokes, and neurological disorders like Parkinson's disease (Brock & Simpson, 1990; Small, 1991). Organically induced depressive symptoms can also be caused by prolonged use of anti-hypertensives (especially reserpine, methyldopa, and beta-blockers), hormones (e.g., estrogen), antiparkinsonian drugs (e.g., levodopa), and analgesics (Allen & Blazer, 1991; Brock & Simpson, 1990; Small, 1991).

Major depressive disorder.The diagnosis of a major depressive disorder requires the presence of five depression symptoms for at least 2 weeks (APA, 1994). Of these, one of the symptoms must be depressed mood or loss of interest or pleasure in most activities. Elderly clients, however, often have a masked presentation: Their affect may be neutral and complaints about changes in mood may be absent (McCullough, 1991; Small, 1991). The clinical picture may be dominated by apathy, withdrawal, vague somatic complaints, and loss of interest (Katz et al., 1988).

Differential diagnosis entails ruling out organic conditions, bipolar disorder, dementia, and a functional psychosis such as schizophrenia. All the medical disorders and medications that can mimic dysthymia are also capable of producing symptoms severe enough to mimic a major depressive disorder (Brock & Simpson, 1990). An organic mood disorder of this severity, however, may have some important differences: Instead of a client's mood seeming neutral, severe organic depression is frequently associated with a flat affect and a monotone voice (Conn, 1991). These features are especially characteristic of stroke victims, of whom 25% develop organic depression (Conn, 1991; Small, 1991). In terms of differential diagnosis, there is some evidence that those with a major depressive disorder versus a medical condition are more likely to report worthlessness and have a history of mood disorder (Allen & Blazer, 1991; Brock & Simpson, 1990).
Whenever an assessment of depression is being made, a history of bipolar disorder needs to be ruled out (APA, 1994). Manic and hypomanic episodes in elderly people are frequently characterized by aggressiveness, anger, and irritability unlike the elation and expansiveness found in younger adults (Katz et al., 1988). As a result, it may feign agitated depression. After the age of 60 years, however, manic episodes become rare and are predominantly due to organic causes such as strokes, hyperthyroidism, or medication side-effects (Conn, 1991).

Late-onset schizophrenia may also mimic a major depressive disorder. The delusions in late-onset schizophrenia tend to be more systematized than in a psychotic depression, and there tend to be fewer depression-like symptoms than are found in a major depressive disorder (Katz et al., 1988).

In older adults especially, a major depressive disorder can be accompanied by cognitive impairments in areas such as memory, attention, concentration, and processing speed (Addonizio & Shamoian, 1986). A number of differences between depression and dementia have been identified that can be useful in making a differential diagnosis. First, the clients with depression are more likely to complain about memory problems and highlight their disabilities (Addonizio & Shamoian, 1986; Small, 1991). Second, depressed clients will generally show more variation of their cognitive performance over 1 month's time, especially in comparison to an individual with AD (Allen & Blazer, 1991). Third, onset of cognitive problems tends to be more sudden (e.g., over weeks) than is seen in AD. Fourth, symptoms such as aphasia, agnosia, and apraxia are rare if only depression is present (Cummings & Benson, 1983). Finally, the depressed client's performance on tests or questions is more likely to show a pattern of errors due to omissions (e.g., not trying, quitting), rather than commission of gross mistakes (Addonizio & Shamoian, 1986; Brock & Simpson, 1990).

A number of depression inventories have been validated with older adults (Allen & Blazer, 1991). Among the most commonly used are the Beck Depression Inventory (Beck, Ward, Mendelson, Mock, & Erbaugh, 1961) and the Geriatric Depression Scale (Yesavage et at., 1983). There is some evidence that indicates that clinicians should use these tests cautiously because clients may underreport their symptoms or have cognitive impairment (Koenig et al., 1992). Inventories also may be less sensitive in identifying depression in elderly African Americans (Koenig et al., 1992).

Recommendations
The discussion has focused on what to look for and what to rule out in the diagnostic process. In this section, suggestions will be offered relative to modifying the diagnostic process when evaluating older adults.

Office Setting
The office setting should take into account the fact that many older adults have some degree of sensory loss and mobility impairment. As a result, good lighting and an environment free of interfering noise is a prerequisite to any assessment (Fields, 1991). Also, seating should be such that it is easy for an older adult to sit and stand without much difficulty.

Scheduling of Appointments
Frequency and duration of interviews need to be tailored to the client's particular needs. Sessions lasting about 40 minutes are generally recommended for older adults (Hussian, 1981), but those with cognitive impairment may only be able to attend for 10 minutes or so, prompting the need for repeated shorter sessions (Fields, 1991). In general, several sessions are required to complete the diagnostic process.

Multimethod Assessment
The complexity of problems that an older adult may have demands using several avenues of data gathering. First, if the client shows cognitive impairment, self-report information may not only be inaccurate, but also misleading (Butler et al., 1992). It is generally useful to collect collateral information from family members, residential staff, and medical personnel. Second, observational data can be easily gleaned from interview behavior (e.g., language usage, affect display) and performance on mental status tasks (e.g., drawing tasks). Third, the counselor should consider routinely doing a mental status exam not only to assess deficits but also to get a benchmark of current functioning. The latter can be used in the future to assess degree of impairment over time. Fourth, measures of functional capacity in areas such as cooking and shopping (Fillenbaum, 1985; Pfeiffer et al., 1981) are important in determining self-care ability (Fields, 1991). Finally, considering the range of potential medical issues, clients who have not been medically evaluated recently should be referred. Additionally, it is useful to obtain a medical release so that the counselor can review relevant medical records.
- Gintner, Gary G.; Differential Diagnosis in Older Adults: Dementia, Depression, and Delirium; Journal of Counseling & Development; Jan/Feb 1995, Vol. 73, Issue 3.

Personal Reflection Exercise #10
The preceding section contained information about differential diagnosis in older adults: dementia, depression, and delirium.  . Write three case study examples regarding how you might use the content of this section in your practice.
Reviewed 2023

Update
Distinguishing Curable from Progressive
Dementias for Defining Cancer Care Options

- Schein C. H. (2023). Distinguishing Curable from Progressive Dementias for Defining Cancer Care Options. Cancers, 15(4), 1055.

Peer-Reviewed Journal Article References:
McGee, J. S. (2019). Illuminating Alzheimer’s disease. Families, Systems, & Health, 37(3), 273.

Peters-Founshtein, G., Peer, M., Rein, Y., Kahana Merhavi, S., Meiner, Z., & Arzy, S. (2018). Mental-orientation: A new approach to assessing patients across the Alzheimer’s disease spectrum. Neuropsychology, 32(6), 690–699.

Singh, M. (2019). Dementia—They say. Families, Systems, & Health, 37(3), 267–269.

QUESTION 19
What is the most common cause of dementia in clients younger than 50 years of age? To select and enter your answer go to Test.

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