(p. 68) Evaluating Dementia
Dementia is not a disease in and of itself; rather, it is a diagnostic classification that refers to a significant decline in intellectual functioning that causes impairment in social and occupational functioning. The reduction in intellectual functioning is acquired; that is, it must represent a decline from a previous level of functioning, which differentiates dementia from congenital mental retardation. It is also persistent, which distinguishes dementia from delirium. Finally, the intellectual dysfunction of dementia affects multiple areas of cognition, in contrast to focal deficits such as aphasia caused by specific neurological lesions.
The methods and criteria used to evaluate dementia vary with the definition of dementia used. The American Psychiatric Association’s fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV, 2000) provides diagnostic criteria for the clinical syndrome of dementia as well as more specific criteria for diagnosing Alzheimer’s disease and vascular dementia. The National Institute on Aging-Alzheimer’s Association (NIA-AA) criteria for diagnosing possible or probable Alzheimer’s disease are more commonly used for research purposes and require neuropsychological assessment. Various consensus groups have developed diagnostic criteria for other, less common forms of dementia, including frontotemporal dementia (FTD; Neary et al., 1998) and dementia with Lewy bodies (DLB; McKeith et al., 1996).
The DSM-IV criteria requires the presence of impaired memory plus impairment in at least one other cognitive domain, including aphasia (language impairment), agnosia (perceptual impairment), apraxia (impaired motor programming), or executive functioning. These clinical criteria are imperfect, however, as memory is not always impaired in dementia, particularly in nonamnestic dementias and dementia that occurs in the early stages of a disease. In addition, more recent definitions of dementia require impairment in three or more cognitive domains so as to decrease the likelihood of misdiagnosing dementia, i.e. committing false positive errors.
The evaluation of dementia requires a careful history, including a detailed clinical interview. The patient may very well be unaware of the extent of his or her level of impairment. Subsequently, information should be obtained from both the patient and a reliable collateral source such as a caregiver or knowledgeable family member. When possible, it is helpful to interview the informant separately so as to obtain information that may not have been voluntarily reported in the presence of the patient. The informant’s information should be compared to that given by the patient to determine the patient’s level of awareness or denial of symptoms. The interview can offer information about the onset and (p. 69) time course of cognitive and behavioral symptoms. Identifying the mode of onset of cognitive change is often difficult for the patient or family members to determine with certainty. Cognitive changes may come to the awareness of others following a “trigger” event. Physical trauma such as surgery, dehydration, or infection, or psychological trauma such as the death of a loved one or a move from familiar living arrangements may unmask symptoms that were previously unnoticed, leading family members to believe that the onset of cognitive decline was acute. In many situations, the death of a spouse uncovers a patient’s cognitive and functional limitations as it becomes clear that the spouse, whether intentionally or not, compensated for the patient’s deficits. Determining the course of the cognitive decline is also important: Is it progressive, stepwise, or fluctuating? A progressive course is typical of most neurodegenerative diseases such as Alzheimer’s disease, while a stepwise course is usually more characteristic of a vascular etiology. Often, family members will report fluctuating levels of cognitive performance. A detailed analysis of this type of course is necessary in order to rule out specific types of dementia, such as DLB, for which alternating levels of arousal represent a primary clinical feature. To investigate whether the course is fluctuating, caregivers may be asked, “Does the patient have good days and bad days?” If so, it is helpful to explore whether there is a pattern to the fluctuations; that is, does the patient perform worse when sleep deprived? The interview also offers the opportunity to assess for any recent changes in the patient’s lifestyle that may contribute to cognitive decline. For example, has the patient’s living situation changed? Has his or her social network or support system been altered? Patients in the early stages of dementia often present with typical cognitive symptoms, and directed questioning can be used to obtain specific examples of such features. Positive responses to questions such as “Do you misplace items more frequently than in the past?” or “Do you frequently forget appointments?” suggest short-term memory impairment. Language functioning can be explored by inquiring as to whether the patient experiences word-finding difficulty or has experienced a change in his or her ability to complete a sentence while speaking. Visuospatial impairment may manifest as difficulty with finding one’s way when driving or walking in unfamiliar places. Reports of difficulty following group conversations or understanding jokes may suggest executive dysfunction.
In addition to cognitive decline, dementia is also associated with mood and behavioral changes. Frequently, patients experiencing cognitive change may appear withdrawn or less interested in social interactions. Whether this alteration reflects the effects of emotional distress such as depression is often unclear to the caregiver. Patients who are cognitively impaired may seem isolative, particularly in large social situations, because they are unable to follow the flow of conversation. They may exhibit a “delay” in terms of responding to portions of earlier conversations as opposed to staying on topic. Less frequently, patients exhibit psychiatric symptoms, including hallucinations or delusions of persecution, particularly as the level of dementia severity increases. Patients and caregivers may not offer specific examples of psychotic behavior, which necessitates careful but sensitive probing about the existence of symptoms through directed questions. In addition to being asked about the presence of visual or auditory hallucinations, for example, “Do you ever see things that are not there, such as people, animals, or insects?” patients can be asked whether they ever feel a “phantom presence” or believe that someone is in the room with them. This line of questioning is especially useful when assessing patients with parkinsonism, who may experience “feeling of presence” or “phantom boarder” delusions. Oftentimes patients will accuse caregivers of infidelity. Given the sensitivity of the topic, the informant can be asked this question privately.
An assessment of functional status is necessary when evaluating a patient for dementia. Questions about activities of daily living (ADLs) should be asked to assess for changes in the patient’s ability to care for himself or herself. One way to do this is to ask the caregiver whether there are specific tasks or activities that the patient is unable to perform as well as he or she did before the onset of cognitive and/or behavioral symptoms. Questions about the (p. 70) patient’s abilities should be posed to assess instrumental (IADLs). For example, is the patient able to manage his or her own finances; specifically, has the patient forgotten to pay bills on time or paid some bills twice? Has the patient made errors when balancing the checkbook? Can the patient make change for a purchase or calculate the tip on a bill? Does the patient require assistance to manage his or her medication regimen? Is the patient driving and, if so, has the quality of his or her driving skill changed? Has he or she become lost or disoriented while walking, driving, or using public transportation? Basic ADLs should also be assessed: Is there any change in hygiene; for example, does the patient require reminders to bathe, groom, or change clothes? Inquiries about social and leisure activities should also be asked: Is the patient reading as much as he or she did in the past? If so, what is being read? Has the patient switched from reading novels and books to reading the newspaper or magazines? Often, dementia patients will read shorter articles, either in newspapers, magazines, or online as opposed to books due to the fact that they may be unable to recall what was previously read in a book. Similarly, patients with dementia frequently lose interest in watching movies due to their difficulty in following the plotline or remembering who characters are. A patient may explain this disinterest in reading or viewing movies by stating that he or she finds them to be boring or uninteresting. This same reasoning is also often used when the patient is confronted with his or her tendency to forget recent conversations; that is, the patient may rationalize that he or she only recalls information that he or she is interested in.
A thorough medical and psychiatric history should be obtained to identify any conditions that can affect one’s mental status. A review of the patient’s past neurological history should include questions about prior head injuries, stroke, tumors, and seizures. A more general medical history is also necessary given that disturbances of endocrine function, such as a thyroid disorder, vitamin deficiencies such as low B12 levels, or metabolic disorders can affect cognitive functioning. It is important to obtain a full list of prescription and over-the-counter medications to assess the possibility that adverse effects which may result from accidental overdoses or poor compliance with medication regimens may be mistaken for dementia. Information regarding current and past use of alcohol and drugs should be obtained, as well as family history of dementia or other neurological disease. Visual acuity and hearing should be assessed to rule out a visual or hearing problem. Psychiatric conditions such as depression often mimic dementia. Previously referred to as “pseudodementia,” the cognitive changes associated with depression represent a substantial percentage of patients who present for evaluation. Obtaining a developmental history is important to rule out any preexisting conditions such as perceptual problems, learning disabilities, or attentional disorders.
Formal neuropsychological testing that uses standardized tests with appropriate normative data provides objective data on cognitive functioning, which assists in making a diagnosis. A comprehensive neuropsychological evaluation should assess all cognitive domains, including memory, language, visuospatial functioning, attention and executive functioning, sensory and motor functioning, and emotional functioning. One of the more difficult aspects of diagnosing dementia is determining whether the current level of intellectual function represents a definitive decline from previous levels. Unless patients have undergone baseline testing prior to the onset of cognitive changes, such as IQ testing while in school, it is often challenging to establish an accurate estimate of premorbid intellectual functioning. Therefore, information obtained from the clinical interview should include demographic and historical data such as education level (including the quality of education received), socioeconomic status, and occupational history. The patient’s cultural background and primary language are also relevant to the evaluation. On neuropsychological testing, premorbid intellectual functioning can be estimated using single-word reading tests (e.g., National Adult Reading Test [NART], Wechsler Test of Adult Reading [WTAR]) that correlate highly with general intellectual functioning but are fairly immune to cognitive changes, as well as subtests on the Wechsler Adult Intelligence Scale (p. 71) (WAIS; Information subtest) that are also considered relatively resistant to cognitive change. Caution should be taken when using such measures with ethnic and racial minorities, however, as they may underestimate premorbid functioning with groups. Finally, a full assessment of emotional functioning, including personality measures where necessary, should be obtained to rule out the effects of psychiatric symptoms such as anxiety and/or depression on cognitive performance.
References and Readings
American Psychiatric Association. (2000). The diagnostic and statistical manual of mental disorders (4th ed.). Washington, DC: American Psychiatric Publishing.Find this resource:
McKeith, I. G., Galasko, D., Kosaka, K., Perry, E. K., Dickson, D. W., & Hansen, L. A. (1996). Consensus guidelines for the clinical and pathologic diagnosis of dementia and Lewy bodies (DLB): Report of the consortium on DLB international workshop. Neurology, 47, 1113–1124.Find this resource:
McKhann, G., Knopman, D. S., Chertknow, H., Hyman, B. T., Jack, C. R., Kawas, C. H., … Phelps, C. H. (2011). The diagnosis of dementia due to Alzheimer’s disease: Recommendations from the National Institute on Aging-Alzheimer’s Association workgroups on diagnostic guidelines for Alzheimer’s disease. Alzheimer’s & Dementia, 7, 263–269.Find this resource:
Neary, D., Snowden, J. S., Gustafson, L., Passant, U., Stuss, D., Black, S., … Benson, D. F. (1998). Frontotemporal lobar degeneration: A consensus on clinical diagnostic criteria. Neurology, 51, 1546–1554.Find this resource:
Chapter 9, “Evaluating the Medical Components of Childhood Developmental and Behavioral Disorders”
Chapter 17, “Adult Neuropsychological Assessment”
Chapter 18, “Developmental Neuropsychological Assessment”
Chapter 19, “Assessment and Intervention for Executive Dysfunction”
Chapter 20, “Assessing and Managing Concussion”
Chapter 58, “Practicing Psychotherapy with Adults Who Have Cognitive Impairments”