Dementia versus Depression

Dementia

Description

• Dementia is not a separate disease entity. Instead, it is a “set of symptoms” which may be associated with many disorders.
• “The essential feature of Dementia is impairment in short- and long-term memory, associated with impairment in abstract thinking, impaired judgment, other disturbances of higher cortical function, or personality change”
• Dementia is not synonymous with declines in intellectual functioning which are associated with normal aging.
• Dementia is never diagnosed unless “the disturbance is severe enough to interfere significantly with work or usual social activities or relationships with others” (1).
• Dementia always has an underlying organic cause. Examples given in the DSM-III-R include:
  • Primary Degenerative Dementia of the Alzheimer’s Type(DAT).
  • Vascular disease (multi-infarct dementia (MID]).
  • CNS infections (viral encephalitis, AIDS, etc.)
  • Brain trauma (especially chronic subdural hematoma)
  • Toxic metabolic disorders (e.g., hypothyroidism)
  • Normal pressure hydrocephalus.
  • Neurologic-diseases (e.g., Huntington’s chorea, multiple sclerosis, Parkinson’s, etc.)

Prevalence

“Estimates of the prevalence of dementia among the elderly…have ranged from 1.3% to 6.2% of persons over 65 years of age for severe dementia, and from 2.6% to 15.4% for those with milder dementia…”

• “The prevalence of dementia appears to be age associated, with a four to sevenfold increase from ages 70-79 to ages greater than 80”
• Alzheimer’s Disease accounts for approximately 1/2 of all cases of dementia, affecting 5-6% of people above age 65

Onset

Dementia is more commonly found among the elderly, but it may occur at, any age after IQ is stable (age 3-4). Therefore, “if a four-year-old developed a chronic neurologic disorder that interfered with previously acquired functions so as to significantly lower intellectual or adaptive functioning, he would be considered to have both dementia and retardation.” (1)

Course

The course of dementia depends on its underlying etiology; it may be progressive, remitting, or static (1).

• Dementias which are due to brain tumors, subdural hematomas, and metabolic factors may have a gradual onset (1).
• Primary Degenerative Dementia of -The Alzheimer Type usually involves slow deterioration over many years, continuing until death (l,2,5)
  • “The condition typically begins so insidiously that often the family is unaware that anything is wrong until a sudden disruption in routine leaves the patient disoriented, confused, and unable to deal with the unfamiliar situation. Because the early behavioral decline is so gradual and unsuspected and because most simple functions — as measured by elementary tests of language and of sensory and motor functions — remain intact in the early stages of the disease … it is difficult to date the onset of the condition with any sureness” (5).
  • Researchers at the New York University Geriatric Study and Treatment Program have outlined three phases in the progression of DAT:
    • The forgetfulness phase: increasing forgetfulness (noticed by the individual and sometimes by others close to him) and accompanying anxiety caused by the forgetfulness (2).
    • The confusion phase: “severe deficit in memory for recent events, difficulty in orientation and concentration, and subtle language deficits (e.g. word finding difficulty) despite generally intact vocabulary and syntax” (2).
    • The dementia phase: “characterized by severe disorientation, abnormalities of language, perception and praxis, and behavioral problems, including motor restlessness, wandering, and psychotic symptoms (e.g., paranoid ideation) (2).
  • Dementia resulting from a clearly defined episode of a neurologic disease (e.g., cerebral hypoxia or encephalitis) may begin quite suddenly, but then remain stationary for a long time (1).
  • In MID (multi-infarct dementia), the deficits are believed to be the result of the accumulation of abrupt vascular episodes (“strokes”). Therefore, the onset of dementia in MID is typically abrupt. There is also a stepwise course of deterioration, with further deficits being noted after each stroke. With MID, the neurological signs and symptoms are more likely to be focal; and there is a history consistent with cerebrovascular accident (CVA), and a history or presence of hypertension” (2,5).
  • “If the underlying cause can be treated (e.g., subdural hematoma), dementia can be arrested or even reversed. However, the more widespread the structural damage to the brain, the less likely clinical improvement” (l)

Memory Problems

The memory problems associated with dementia will vary depending on the severity of the dementia (1,4).

• Mild dementia; moderate memory loss which is more marked for recent events (e.g., forgetting names, telephone numbers, directions, conversations’. and events of the day) (1).
• Severe dementia: “only highly learned material is retained, and new information is rapidly forgotten. The person may leave a task unfinished because of forgetting to return to it after an interruption. This may cause a person to leave water running in the sink or to neglect to turn off the stove” (1).
• Advanced stages of dementia: “memory impairment is often so severe that the person forgets the names of close relatives, his own occupation, schooling, birthday, or occasionally even his own name (1)”

Abstract Thinking Problems

Impairment in abstract thinking will result in:

• Trouble coping with novel tasks, especially if pressed for time (1).
• Problems with new situations or tasks that require the processing of new and complex information (1).

Personality changes

• Alteration or accentuation of premorbid traits:
  • A previously active person may become increasingly apathetic and withdrawn from social interactions; he may be described as “not himself anymore” (1).
  • A previously neat and meticulous person may become disorganized and extremely careless about his appearance and possessions (1).
  • Others may display accentuated preexisting traits. Common changes include extreme irritability, cantankerousness, meanness, tactlessness, impulsiveness, and sexual inappropriateness (1,2).

Anxiety and depression (1).

• These may occur as a psychological reaction to the fact that they are no longer able to function as well as they have in the past (1,4).
• Paranoid ideation, resulting in false accusations, or verbal and physical attacks (e.g., accusing spouse of infidelity) (1).
• Increased vulnerability to physical and psychosocial stressors (e.g., minor surgery or retirement may aggravate deficits) (1).

Mortality

“While excess mortality varies with age of onset and diagnosis, overall, dementia patients have approximately one-third the life expectancy of non-demented age-matched individuals…” (2)

Depression

Features

• The Essential feature is a depressed mood or loss of interest or pleasure in all, or almost all, activities. Clinical depression also results in a diminished ability to think or concentrate (1).
• Not initiated or maintained by organic factors (1).

Onset

variable … may be sudden, but usually develops over days to weeks (1).

Duration

variable … untreated, usually lasts 6 months or more, then remission of symptoms and return to previous functioning level…but chronic type can go two years (1).

Impairment

Varies … but there is always some interference in social and occupational functioning (1).

Prevalence

“In elderly citizens who dwell in the community, the prevalence of clinical depression has been reported to be as high as 13% …. As many as 20% to 25% of elderly patients with concurrent medical illnesses are depressed” (6)

Memory & Learning Problems

Memory and learning functions are impaired in depressed patients (3,4,6).

• Deficits are apparent in sustained attention on tasks requiring “effort.” This deficit interferes both with the reception of new information and with its initial processing (3).
• Deficits in initial acquisition appear to be related to later recall failures. Weingartner et al (1981) demonstrated that memory deficits are not apparent when information is presented in a structured format. As the presentation structure is disrupted, however, memory problems develop (3,6).
• Depressed patients appear to retain information once it is learned, although it is uncertain how effectively this is done (3).
• Retrieval deficits are apparent in depressed patients. Part of this failure may be due to poor initial processing. However, “effort” may also be a factor because recognition memory is less impaired than recall memory (3).
• As a result, some researchers speculate that depressed patients do not really suffer from a deficit in memory per se but that their memory problems stem from deficits in motivation, drive, and attention (6).

Motor Problems

• Depressed patients demonstrate deficits on several motor performance tasks (e.g., tapping) and on skills requiring sustained effort, concentration, perceptual flexibility, abstract thinking, and performance accuracy (3,6).
• Reaction time is longer in depressed patients (thus indicating longer times required for information processing) (3).
• A Major Depressive Episode may involve symptoms severe enough to be mistaken for dementia: memory problems, difficulty thinking and concentrating, overall reduction in IQ; the individual also may perform poorly on mental status exam and neuropsychological testing (1).

Pseudodementia

Definition

Pseudodementia is a label given to psychiatric disorders (such as depression, schizophrenia, and hysterical disorders) which involve dementia-type symptoms and which persist if not treated (3,6).

Etiology

Pseudodementia can occur in numerous disorders: hysterical disorders, schizophrenia, etc. However, major depression appears to be the most frequent cause. Numerous studies have documented the presence of cognitive deficit in depression…, and older depressed patients (also the prime -targets for dementia) may be more likely to show such deficits…” (2).

Progression

There is some disagreement as to whether or not patients who have an organic-based dementia which is not progressive should also be included in the pseudodementia grouping. The argument is that, rather than differentiating the groups on the basis of organic vs. non-organic, it would be more pragmatic to divide the groups according to favorable prognosis for treatment vs. unlikely to improve (2).

• Some patients with “organic” findings on neuropsychological testing experienced complete remission of symptoms following treatment. Others improved but showed residual deficits (3).
• “It may be impossible to determine where a psychiatric disorder leaves off and a neurological disorder begins. Indeed such a distinction may not be necessary as long as one establishes that the course is non-progressive. Therapeutic interventions are based on the presence of responsive target symptoms, and although a diagnosis is important, it may not be essential for initiating effective treatment measures” (3).

Problems in Differentiation

Imprecise use of the term “dementia”

• The disagreement over whether all organic-based dementias should, in fact be called dementia, or whether those which are not progressive in nature should be termed “pseudodementia” poses problems in itself (3,5).
• “Imprecision in using the term ‘dementia’ can confuse discussions of patients and conceptualization of their disorders” (5).

Intellectual functioning declines with normal aging

This normal decline can be mistaken for dementia. (2,4).

• In the early stages of dementia (when symptoms are relatively mild), differentiation from the memory changes associated with normal aging is difficult or impossible (2,3).
• “Elderly depressed patients often do not report the common symptoms of depression associated with younger adults. Their only complaint may be of memory problems” (4).
  • “The inexperienced clinician might focus only on the assessment of memory and, indeed, discern short-term memory difficulties in such an individual” (4).
  • If depression is treated, the short-term memory difficulties might also remit (4).
  • “If the clinician focuses only on the memory aspect of the assessment, it is possible to misdiagnose an elderly patient as having a progressive dementing illness when the problem is really depression. This last kind of assessment error can have a profound impact on the life of an individual so diagnosed” (4).
• Depression is frequently accompanied by cognitive problems, especially in older persons; and, in some cases, these cognitive problems are severe enough to be labeled pseudodementia (1,2).

Overlapping signs and symptoms

• “The signs and symptoms of neurologic disorder accompanied by dementia (e.g., Alzheimer’s, Huntington’s, and Parkinson’s disease) may have some overlap with those of depression…” (2).
  • Both interfere with social and occupational functioning.
    • To qualify as dementia, it must interfere significantly (1,2).
    • With depression, the degree of interference may be mild; or it may be so severe that the person is unable to feed or clothe himself. (1)
• Both result in withdrawal from activities:
  • With depression, this is mainly due to loss of interest (1).
  • With dementia, it may be due to anxiety and attempts to hide deteriorating faculties as well as loss of interest resulting from depression (1).
• Depression often occurs as a complication of dementia (2,3).
  • “Depressive reactions are often the first overt sign of something wrong in a person who is experiencing the very earliest subjective symptoms of a dementing process” (5).
  • Reifler et al (1982) diagnosed depression in 27 of 103 geriatric outpatients who conformed to the DSM-III-R diagnosis of dementia. (3)
  • Reifler found that, overall, depression decreased as the severity of the dementia increased (3).
• “Unfortunately, we have no sound method for demarcating the boundaries between (1) intellectually intact depressed elderly individuals; (2) others who have significant affective symptoms and substantial cognitive impairment, where the intellectual deficits are reversible following vigorous therapeutic intervention; and (3) those who suffer a progressive neurological disease which manifests itself with both behavioral symptoms” (3).

• Because the symptoms of normal aging, depression, and mild dementia are quite similar, misdiagnosis does occur when the clinician confuses signs and symptoms of dementia with those of other disorders (2).
• “Those aspects of the clinical presentation of both an early dementing process and depression that are most likely to contribute to misdiagnosis are depressed mood or agitation; a history of psychiatric disturbance; psychomotor retardation; impaired immediate memory and learning abilities; defective attention, concentration, and tracking; impaired orientation; an overall shoddy quality to cognitive products; and listlessness with loss of interest in one’s surroundings and, often, in selfcare” (5).

Frequency of misdiagnosis:

• Ron and colleagues (1979) conducted a 5-15 year follow-up study on 51 patients discharged from hospitals with a diagnosis of presenile dementia. All of these patients were under age 65 at time of diagnosis. The original diagnosis was confirmed in 35 cases (69%) and rejected in 16 (31%). Retrospective diagnoses of the latter group were: eight affective illnesses, one paranoid psychosis, one schizophrenic disorder, three Parkinson’s disease, two nonprogressive brain damage of uncertain etiology, and one transient acute organic reaction with marked affective symptoms (2).
• Garcia et al (1982) conducted a “study of 100 older patients referred to a specialized outpatient dementia clinic. Twenty-six were found to be not demented. Of these, 15 were diagnosed as depressed, seven as having other miscellaneous neuropsychiatric disorders, and four as being normal. Thus, misdiagnosis of dementia appears to be common, with differentiation from depression posing the greatest difficulty” (2).

Importance of Accurate Diagnosis

• Accurate differential diagnosis is important because many of the causes of pseudodementia are both treatable and reversible (2).
• When uncertain, the least serious diagnosis (i.e., depression or pseudodementia) should be given, and the appropriate treatment prescribed. This prevents the patient from being dented potentially helpful treatment because the clinician has assumed the more hopeless diagnosis of dementia (1,3).

Diagnostic Tools

CTScans

• Because it is sensitive to focal lesions, CT scanning has been useful in evaluating dementia; however, its use as a diagnostic tool in helping to differentiate DAT or MID patients from normally aging or depressed older persons remains in doubt (2).
• “Although DAT patients, as a group, show greater ventricular and sulcal enlargement than age-matched control subjects, there is considerable group overlap…” (2)

EEG

Same problem with differentiating from normal aging.

Mental Status Exams

• “A clinical mental status examination and thorough history typically reveal the syndrome of dementia once the patient is several years into the course of a dementing illness. However, the clinician must be cautious that his expectations for cognitive functioning in the elderly are not inappropriate. Intellectual functioning, learning and memory, psychomotor speed, and sensory/perceptual functioning all show age-related changes in adulthood. Consequently, the use of mental status examination protocols with age-appropriate standardization is important” (2).
• “The Geriatric Mental Status Interview (GMS), developed by Gurland et al, (1976), is one of the more comprehensive mental status examinations available. The GMS is a semistructured interview technique which can be administered by a trained interviewer in typically less than an hour. Between 100 and 200 questions, concerning dimensions such as cognitive functioning (including specific tests of orientation and memory), affective state, behavior symptoms, and somatic concerns are asked, resulting in ratings on 500 items …. Valid discrimination of dementia from functional psychiatric disorders (including depression) has been demonstrated for the GMS….” (2)
• The GMS has been expanded and incorporated into the Comprehensive Assessment and Referral Evaluation (CARE), which covers psychiatric, medical, nutritional, economic, and social problems. The items of the CAPE that are most relevant to the assessment of dementia demonstrate high interrater reliability …. Two relatively short CARE scales, for assessing cognitive impairment and depression respectively, together misclassified only 2% of a sample of 107 depressed and 31 demented older persons (2)
• The disadvantage of the GMS and the CARE are that “they are relatively lengthy to administer and require specific training. Brief, specific mental status examination protocols are available for examining patients with known or suspected dementia” (e.g., the orientation and memory examination of Blessed, Tomlinson, and Roth [1968] and the Mint-Mental State Examination of Folstein, Folstein, and McHugh [1975]) (2).
• “An additional advantage of the very brief mental status screening instruments is that they “can be administered to more severely demented patients who may not be examinable with more complex psychometric instruments, thus allowing repeat examinations over several years of the patient’s illness …. However, these advantages also result in unacceptable high false-negative errors for patients early in the course of dementia” (2).

Dementia Rating Scales

• These attempt to combine the brevity and ease of brief mental status screening instruments with a tool that samples a wide range of cognitive functions, using both interview question and direct performance measures. (2)
• The Mattis Dementia Rating Scale (MDRS) is one of the more widely used dementia rating scales. “Items of the MDRS are grouped into five areas, designed to assess attention, initiation and perseveration, construction, conceptualization, and memory … Scores from all five areas are also summed to provide a general index of dementia severity…” (2).
• “Since DAT, MID. and several other dementias progressively deteriorate, there is a need for instruments that can be repeatedly administered throughout the course of dementia …. Observation-based rating scales are a useful addition to such instruments since they typically do not necessitate patient cooperation ‘. and often provide ratings of behavioral features observed later in the course of dementia. An example of a rating scale developed specifically to evaluate various ‘stages’ throughout the course of dementia … is the Global Deterioration Scale of Primary Degenerative Dementia (GDS) … It defines seven stages in the course of dementia, with well-specified observational criteria” (2).

Comprehensive Neuropsychological Assessment

• “While mental status examination protocols and dementia rating scales play an important role in diagnostic assessment and patient follow-up, they are often inadequate alone. Typically, they are relatively insensitive to very mild dementia, and they lack sufficient specificity to separate various disorders presenting as dementia” (2).
• The Halstead-Reitan battery has frequently been used in the study of dementia, and normative data are available for the battery. However. the difficulty level of some of its subtests may make it most useful for milder forms of dementia (l)
• “While there is some variability in the specific tests neuropsychologists include in a recommended battery, most agree on the need to sample a range of cognitive functions, including general intelligence, memory, attention, language, perception, and praxis” (2). (Praxis refers to the motor integrationemployed in the execution of complex learned movements.)
• Assessment of intelligence:
  • Important because impairment in intellectual functioning is one of the defining features of dementia (2).
  • “One attempt to improve the accuracy of the WAIS in the diagnosis of dementia is to employ procedures that estimate intellectual decline.
    • Wechsler’s (1958) deterioration index uses several of the WAIS subtests showing least decline with age as indicators of premorbid levels, with other subtests, more sensitive to the effects of age, as measures of present levels. Such approaches are problematic in that they assume the manifestations of dementia to be similar to those of normal aging; and the results of validation studies employing such deterioration indices generally have not been encouraging.(2)
    • “An alternative approach is to estimate premorbid intelligence by applying an equation differentially weighting age, sex, race, years of formal education, and occupation. The application of such a formula, based upon such a regression has been supported in a recent validation study (Wilson et al, 1979). However, given the variation in IQ among people with comparable educational and occupational backgrounds, caution needs to be exercised in the clinical application of this estimation equation” (2).
    • “Abstract thinking ability is most frequently evaluated by examining WAIS Similarities and Comprehension (“proverbs” items) subtests. Other procedures for evaluating abstraction ability and cognitive flexibility, such as the Wisconsin Card Sorting Test, are available, but adequate norms for older age groups are not widely available, and its specific validity in assessing dementia remains to be empirically demonstrated” (2).
• Memory Assessment:
  • Memory impairment is another essential feature for the diagnosis of dementia. The Wechsler Memory Scale (WMS) is the instrument most often used to assess this (2).
  • Proper interpretation depends on the application of age-appropriate norms (2).
  • Digit span, although relatively unaffected by normal aging … becomes lncreasingly impaired over time in DAT” (2).
• Language Assessment:
  • “One dimension of verbal impairment that appears early in the course of the disease (DAT) is loss of spontaneity so that conversation always has to be initiated by someone or something else … In extreme cases, a verbally capable patient may become mute” (5).
  • “The loss of verbal spontaneity characteristic of patients with Alzheimer’s disease is typically reflected in dysfluency (i.e., difficulty in generating words). Thus verbal fluency tests are sensitive to this problem” (5)
  • On the Boston Naming Test, DAT patients make significantly more errors than age- and education matched controls (2).
  • DAT patients also make more errors on the object and body-naming portions of the Boston Diagnostic Aphasia Examination.
  • It is important to note that, although naming errors are common with DAT.. they may not occur in other types of dementia (e.g., those associated with Huntington’s and Parkinson’s diseases).
  • Both the Boston Naming Test and The Boston Diagnostic Aphasia Examination have normative data (both by age and education) for ages 25-85 (2).

• Perceptual Assessment:
  • Perceptual deficits in dementia tend to be more frequent and apparent as the severity of the dementia increases over time (2).
  • Both the Benton Facial Recognition Test and the Benton Line Orientation Test have been shown to be valid instruments for assessing dementia. Deficits on these tests were common for dementia patients, but rare for normal controls. In addition, both of these tests have available normative data for ages 65-84 (2).
• Constructional Ability
  • Assessed by the Block Design subtest of the WAIS-R or by various drawing tests (2).
  • “Studies have consistently demonstrated Block Design impairment, inability to copy two-dimensional geometric forms, and significantly more errors in drawing the Bender-Gestalt geometric figures” (2).

Differential Diagnosis

Identify Signs and Symptoms

“The first step in diagnosis is the identification of signs and symptoms which raise the suspicion of dementia” (2).

Does the condition have an organic basis?

• If not, it does not meet the DSM-III-R diagnostic criteria for dementia (1).
• If it does have an organic basis, is the disorder progressive or non-progressive? Is the underlying cause likely to improve with treatment? (2,3)

Deterioration?

Has there been a significant deterioration of cognitive abilities which cannot be explained by normal aging, depression, etc.?

• If the deterioration is not severe enough to significantly interfere with work, usual social activities, or relationships with others, it does not meet the DSM-III-R criteria for dementia (1).
• Miller (1977) reviewed ten dementia studies and found that only one of these studies failed to find average IQs below the expected population mean of 100. In all of these studies which utilized controls, the dementia group always showed lower scores than the controls (2)
• Individuals with dementia tend to have greater variability in their subtest scores than age-matched controls (2).
• Coolidge et al found that, with early Alzheimer’s patients, “the highest scores are obtained on tests of overlearned behaviors presented in a familiar format and of immediate memory recall. Thus, Information, Vocabulary, many Comprehension and Similarities items, and Digits Forward (-Digit Span) will be performed relatively well, even long after the patient is not capable of caring for himself. The more the task, is unfamiliar, abstract, speed-dependent, and taxes the patient’s dwindled capacity for attention and learning, the more likely it is that he will do poorly: Block Design, Digit Symbol, and Digits Backward typically vie for the bottom rank among test scores” (5).
• “A Vocabulary subtest score that is at least twice as large as the Block Design subtest score is a highly likely indicator of dementia and rarely if ever occurs among depressed patients”
• Even so, an examination of WAIS-R score patterns or levels by themselves may not be very helpful in differentiating dementia from depressive pseudodementia. Numerous other factors need to be considered. (2)

Is there depression?

“If the symptoms suggesting a Major Depressive Episode are at least as prominent as those suggesting Dementia, it is best to diagnose Major Depressive Episode and to assume that the symptoms suggesting Dementia are secondary to the depression.” If the symptoms do not improve with treatment, then the appropriate diagnosis is dementia with depression” (1).

Duration of symptoms?

How long have the symptoms been apparent?

• Cognitive deterioration associated with dementia typically has a slow and insidious onset; cognitive impairments accompanying depressive reactions are more likely to evolve over a much shorter period of time (5,6). The exception is dementia associated with MID, which has a sudden onset and is associated with a vascular event (e.g., stroke) (115).
• Dementia (especially DAT) doesn’t usually come to professional attention until several years into the disorder. At this point, thorough history taking, a careful mental status exam, and knowledgeable application of psychological and neuropsychological testing instruments are reasonably successful in differentiating the demented patient from those suffering from normal aging processes, depression, etc. (2,5).
• In depressive pseudodementia, onset can frequently be dated with some precision because of its association with some precipitating event or series of events. The presence of such an event or events, however, does not rule out the possibility of dementia because the timing of the events may be coincidental or may be the result of problems created by as-yet undiagnosed symptoms (1,5,6).

Vegatative Symptoms of Depression?

“Dementia patients are much less likely to suffer vegetative symptoms of depression such as loss of appetite, disturbed sleep, and constipation (5).

Speech?

“The structure and content of speech remain essentially in tact in depression but deteriorate in dementia of Alzheimer’s type” (5).

Learning?

“Depressed pseudodemented patients can learn, showing this on delayed recall and recognition memory tasks even when their immediate recall performance may have been significantly impaired” (5).

Aphasia, Apraxia, Agnosia?

“The presence of aphasias, apraxias, or agnosias clearly distinguishes an organic dementia from the pseudodementia of depression” (5).

Drawing and Construction?

“Quite early in the course of their illness, dementia patients show relatively severe impairment on drawing and constructional tasks, making virtually no appropriate response or a fragment of a response that may be distorted by perseverations despite their obvious efforts to do as asked. In contrast, the performance of depressed patients on drawing and construction tasks may be careless, shabby, or incomplete due to apathy, low energy level, and poor motivation; but, if given enough time and encouragement, they may make a recognizable and often fully accurate response” (5)

Orientation?

Disorientation is found with both depression and dementia. In depression, however, this disorientation in often inconsistent and may be due to an “attentional motivational deficit.” In dementia, the disorientation is more consistent and, therefore, predictable (5).

Insight?

“Depressed patients are more likely to be keenly aware of their impaired cognition, making much of it: in fact, their complaints of poor memory in particular may far exceed measured impairment …. Dementia patients, in contrast, are not likely to be aware of the extent of their cognitive deficits and may even report improvement as they lose the capacity for critical self-awareness” (5).

Differential Diagnosis Table

Pseudodementia	Dementia
Clinical course & History	Clinical course & History
Family always aware of dysfunction & its severity	Family often unaware of dysfunction & its severity
Onset can be dated with some precision	Onset can be dated only within broad limits
Symptoms of short duration before medical help is sought	Symptoms usually of long duration before medical help is sought
Rapid progression of symptoms after onset	Slow progression of symptoms throughout course
History of previous psychiatric dysfunction common	History of previous psychiatric dysfunction unusual

Source: Wells, C.E. (1979) “Pseudodementia” American Journal of Psychiatry, 136,7, Jul 1979.

Another Summary

Depressed Patients Demonstrate deficits in

• Motor performance tasks
• Sustained effort or concentration
• Perceptual flexibility
• Abstract thinking
• Performance accuracy
• Reaction time (and therefore, processing speed is also affected)
• May also perform poorly on a MSE, neuropsych testing, and decreased overall IQ score

Pseudodementia

• Label given to psychiatric disorders (e.g., depression, schizophrenia, and hysterical disorders) which cause dementia type symptoms
• Major depression is the most frequent cause

Problems in differentiating depression vs. dementia

• Elderly depressed patients often do not report the affective symptoms of depression; instead frequently present with complaints of memory difficulties
• Depression often occurs as a complication of dementia

References

1. American Psychiatric Association. (1987). Diagnostic and statistical manual of mental disorders (third edition – revised). Washington, D.C.: Author.

2. Kaszniak, A. W. (1986). The neuropsychology of dementia. In I. Grant and K. M. Adams (Eds.), Neuropsychological assessment of neuropsychiatric disorders (pp- 172-220). NY: Oxford University Press.

3. Caine, E. D. (1986). The neuropsychology of depression: The pseudodementia syndrome. In I. Grant and K. M. Adams (Eds.) Neuropsychological assessment of neuropsychiatric disorders (pp. 221-244). NY: Oxford Press.

4. MacInnes, W. D., & Robbins, E. E. (1987). Brief neuropsychological assessment of memory. In L. C. Hartlage, M. J. Asken, & J. L. Hornsby (-Eds.). Essentials of neuropsychological assessment (pp- 175-196). NY: Sprinqer Publishing Company.

5. Lezak, M. (1985). Neuropsychological assessment. N.Y: Oxford University Press.

6. Jenike, M. (1988). Depression and other Psychiatric disorders. In M. S. Albert and M. B. Moss (Eds.), Geriatric neuropsychology (pp 115-144). NY: The Guilford Press.