Alzheimer's Disease and Related Dementias, 6 unitsPage 5 of 15

3. Identifying Alzheimer’s and Other Types of Dementia in the Clinical Setting

Currently, the identification and diagnosis of dementia in the clinical setting is mostly based on a clinician’s suspicion of patient symptoms or caregiver concerns. Because the onset of dementia is gradual and the early symptoms of dementia are extremely common, cognitive or cognitive-related functional complaints may not be obvious during routine office visits unless they are directly assessed. To make matters more complicated, many individuals with subjective memory complaints often have normal cognition when tested (Lin et al., 2013). Unfortunately, patients with unrecognized impairment usually do not get tested for reversible causes of dementia, do not get counseling regarding the disease process or advanced care planning, and are not offered treatment (Cho et al., 2014).

Several barriers may contribute to a missed or delayed diagnosis of dementia, particularly in the primary care setting:

  • Physician and patient lack of knowledge
  • Physicians’ concerns about over-diagnosis and labeling
  • Lack of appropriate assessment tools
  • Patient’s refusal to be assessed for dementia
  • Time and financial constraints (Lin et al, 2013)

Did You Know . . .

Compared to patients who see a geriatrician or neurologist, dementia patients followed up exclusively by primary care physicians are less likely to receive a specific dementia diagnosis and less likely to have their initial diagnosis change over time. They are also less likely to have neuroimaging or receive dementia medication (Cho et al., 2014).

Screening for Cognitive Impairment

Screening is a method for detecting dysfunction or disease before an individual would normally seek medical care. Screening tests are usually administered to individuals without current symptoms, but who may be at high risk for certain adverse outcomes. Screening has the potential to identify very early signs of dementia, which may allow early diagnosis and treatment. It also offers the chance to identify reversible causes of dementia (such as high blood pressure) and treat conditions that contribute to cognitive decline.

Screening tests for cognitive impairment in the clinical setting generally include asking patients to perform a series of tasks that assess at least one cognitive domain (memory, attention, language, and visuospatial* or executive functioning). Blood tests and radiology examinations are not currently used as screening tests but are often used after a positive screening result to confirm the diagnosis of dementia and determine its subtype (USPSTF, 2014).

*Visuospatial ability: the ability to perceive and understand the special relationship between objects within the environment that are within our field of vision, including our own body’s relationship to other objects.

In 2011 Medicare began covering the “detection of cognitive impairment” as a part of the annual wellness visit benefit, which is mandated by the Affordable Care Act. However, the recommendations issued by the Centers for Medicare and Medicaid Services (CMS) provide little guidance on recommended screening instruments or techniques, other than directing providers to use direct observation and consider information from informants (Lin et al., 2013).

A strong argument in favor of screening for cognitive impairment is that knowledge of the patient’s cognitive status is important for the management of comorbid conditions. Cognitive impairment can affect the management of comorbid conditions and may lead to worsened outcomes of the comorbid conditions. Keep in mind that cognitive impairment may lead patients to report symptoms and health behaviors inaccurately, may decrease their ability to consent to treatments, may affect medication adherence, and may make followup of chronic conditions challenging (Lin et al., 2013).

Additionally, because the sensitivity of a clinician’s diagnosis appears to be strongly related to dementia severity, most people with dementia are not diagnosed until the moderate to severe stages of the disease. Screening tests in all or targeted older adults may help identify patients with dementia or mild cognitive impairment that is otherwise missed (Lin et al., 2013).

Although no professional organizations explicitly recommend screening for dementia in asymptomatic adults, many groups have recommended assessing the cognitive abilities of older adults who present with cognitive or cognitive-related functional complaints (Lin et al., 2013).

The Alzheimer’s Association has published guidance for the detection of cognitive impairment during the annual wellness visit and recommended an algorithm involving a health risk assessment, patient observation, and unstructured questioning. The Alzheimer’s Association recommends the use of a brief structured assessment if signs or symptoms of cognitive impairment are present or if an informant is not available to confirm the absence of signs or symptoms (USPSTF, 2014).

Due to the many obstacles associated with screening for dementia, the U.S. Preventive Services Task Force has recommended that, for cognitive impairment in older adults, current evidence is insufficient to assess the balance of benefits and harms of screening (USPSTF, 2014).

Diagnosing Alzheimer’s and Dementia

Diagnosis involves a thorough medical evaluation, medical history, and testing of mental status. Diagnostic tests are performed to rule out reversible causes of dementia such as drug interactions, depression, delirium, thyroid problems, alcohol and drug abuse, and vitamin deficiencies.

Diagnosis of Alzheimer’s disease and other types of dementia is based on symptoms. This generally includes a gradual decline in mental capacity, changes in behavior, and the eventual loss of the ability to live independently. As yet, there is no blood test or imaging technique that can definitively diagnose dementia.

The National Institute on Aging and the Alzheimer’s Association (NIA/AA) has published guidelines for the diagnosis of Alzheimer’s disease. The diagnostic criteria are as follows:

  1. A gradual, progressive decline in cognition that represents a deterioration from a previous higher level;
  2. Cognitive or behavioral impairment evident in at least two of the following domains:
    1. episodic memory1
    2. executive functioning2
    3. visuospatial abilities3
    4. language functions,
    5. personality and/or behavior
  3. Significant functional impairment that affects the individual’s ability to carry out daily living activities
  4. A situation in which symptoms are not better accounted for by delirium or another mental disorder, stroke, another dementing condition (ie, vascular dementia, frontal-temporal dementia) or other neurologic condition, or the effects of a medication (DeFina et al., 2013).

1Episodic memory: a type of long-term memory associated with personal, individual events, places, people, time, and emotions (a person’s remembrance of who, what, when, where, and why).

2Executive functioning: within the frontal lobe, the part of the brain that oversees or controls planning, attention, ethical behavior, memory, reasoning, problem solving, as well as other cognitive functions.

3Visuospatial abilities: the ability to perceive and understand the special relationship between objects within the environment that are within our field of vision, including our own body’s relationship to other objects.

The Diagnostic and Statistical Manual of Mental Disorders 5 (DSM-5) contains updated criteria for diagnosing Alzheimer’s disease that parallel the NIA-AA diagnostic guidelines. Clinicians should familiarize themselves with these revised criteria, listed within the Neurocognitive Disorders section of the DSM-5 because the criteria contained in the prior DSM-IV-TR are not reflective of the current state of the literature (DeFina et al., 2013).

1Hachinski Ischemic Scale: Used to identify a vascular component once dementia has been diagnosed. Not a validated diagnostic tool.
2ADDTC: Alzheimer’s Disease Diagnostic and Treatment Centers
3NINCDS-ADRDA: National Institute of Neurological and Communicative Disorders and Stroke and Alzheimer’s Disease and Related Disorders Association (now known as the Alzheimer’s Association).
Source: Modified from Beydoun et al., 2014.

Diagnostic criteria of Alzheimer’s Disease,
Vascular Dementia, and other Dementias

Alzheimer’s disease

Development of multiple cognitive deficits, with both memory impairment and one (or more) of the following cognitive disturbances:

  • Aphasia (language disturbance)
  • Apraxia (learned motor skills disturbance)
  • Agnosia (visuospatial/sensory disturbance)
  • Executive functioning (foresight, planning, insight anticipation)
  • Significant impairment in social or occupational functioning, representing a significant decline from a previous level of functioning

Other diagnostic criteria: Hachinski Ischemic Score,1 ICD-10; DSM-IV; ADDTC,2 updated NINCDS-ADRDA.3

Vascular Dementia (NINDS-AIREN1)

Cognitive decline from previous higher level of function in three areas of function including memory

Evidence of cerebrovascular disease by examination

Evidence of cerebrovascular disease by neuroimaging

Onset either abrupt or within three months of a recognized stroke

Vascular Dementia (Modified Hachinski Ischemia Score2: ≥4)

Two-point items

  • Abrupt onset
  • History of stroke
  • Focal neurologic symptoms

One-point items

  • Stepwise deterioration
  • Somatic complaints
  • History of hypertension
  • Emotional incontinence

Other diagnostic criteria: ICD-10; DSM-5

Frontal-Parietal Dementia

Behavioral or cognitive deficits manifested by either:

  • Early and progressive personality change, with problems in modulating behavior; inappropriate responses/activities
  • Early and progressive language changes, with problems in language expression, word meaning, severe dysnomia

Deficits represent a decline from baseline and cause significant impairment in social and occupational functioning

Course characterized by gradual onset and continuing decline in function

Other causes (eg, stroke, delirium) are excluded

Gradual onset and progressive cognitive decline

Dementia with Lewy Bodies

Fluctuating in cognitive performance:

  • Marked variation in cognition or function, or episodic confusion/decreased responsiveness
  • Visual hallucinations: Usually well formed, unprovoked, benign

Parkinsonism: Can be identical to Parkinson’s Disease (PD), milder or symmetric

Parkinson’s Disease with Dementia

Bradyphrenia (slowness of thought)

Executive impairment

Neuropsychiatric symptoms


Clinical Index to Predict Progression

To help clinicians better understand the progression of Alzheimer’s disease, researchers at the University of California, San Francisco have developed a brief clinical index, which they used to predict whether 382 older adults diagnosed with a certain type of mild cognitive impairment would progress to probable Alzheimer’s disease within 3 years. The index utilizes eight items that are readily obtainable in most clinical settings:

  • Gender
  • Four questions regarding caregiver report of the patients’ behaviors (stubborn/resists help and upset when separated) and functional status (difficulty shopping alone and forgets appointments) and
  • Three items focusing on ability to complete basic cognitive tasks (10-item list word recall, orientation to time and place and clock draw test) (Lee et al., 2014).

Researchers also used other measures, including demographics, comorbid conditions, caregiver report of participant symptoms and function, and participant performance on individual items from basic neuropsychological scales. In this study, subjects had a mean age of 75 years and 43% progressed to probable Alzheimer’s disease within 3 years (Lee et al., 2014).

Important predictors of progression included being female, resisting help, becoming upset when separated from a trusted caregiver, difficulty shopping alone, forgetting appointments, number of words recalled from a 10-word list, orientation and difficulty drawing a clock. Fourteen percent of subjects with low risk scores converted to probable Alzheimer’s disease over 3 years, compared to 51% of those with moderate risk scores and 91% of those with high risk scores (Lee et al., 2014).

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