Approach to the Patient with Memory Loss, Mild Cognitive Impairment, or Dementia

In this chapter we propose a strategy for evaluating patients with concerns about their memory and/or other aspects of cognition that will lead to a diagnosis and treatment plan.

Quick Start

• A two-step approach to evaluate patients with cognitive decline is suggested: • Determining if mild cognitive impairment or dementia is present • Determining the disease or diseases that are the cause. • This two-step approach is consistent with the diagnostic guidelines proposed in Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) and by the National Institutes on Aging–Alzheimer’s Association workgroup. • The spectrum of changes in memory and cognition in aging includes: • Age-associated memory change (normal aging) • Mild Cognitive Impairment (MCI)/Mild Neurocognitive Disorder • Dementia/Major Neurocognitive Disorder. • Dementing disorders of aging are now considered on a continuum.
Diagnostic criteria	• Common criteria for dementia include: • Significant cognitive decline as • reported by the patient, a knowledgeable informant, or observed by the clinician, and • documented by formal or informal neuropsychological testing. • Cognitive impairment sufficient to interfere with independence in everyday activities. • Common criteria for mild cognitive impairment include: • Cognitive decline as • reported by the patient, a knowledgeable informant, or observed by the clinician, and • documented by formal or informal neuropsychological testing. • Cognitive impairment does not interfere with independence in everyday activities.
Most likely differential diagnosis by history, symptom, or sign (see Table 3-1 for other considerations)	• Memory loss prominent • Alzheimer’s disease. • Rigidity, tremor, gait disturbance, and/or parkinsonism present: • Dementia with Lewy bodies. • Visual hallucinations of people or animals present: • Dementia with Lewy bodies. • Behavioral issues early and prominent and/or executive dysfunction • Alzheimer’s disease • Frontotemporal dementia. • Language and/or speech dysfunction early and prominent • Alzheimer’s disease • Primary progressive aphasia. • History of strokes and/or transient ischemic attacks (TIAs) • Vascular dementia • Alzheimer’s disease. • History of contact sports and/or multiple concussions • Alzheimer’s disease • Chronic traumatic encephalopathy. • Rapid cognitive deterioration • Medication side effects • Acute medical problem • Acute neurologic problem.

A Two-Step Approach

In approaching the diagnosis of the diseases that cause dementia, we suggest a two-step approach: (1) determining if mild cognitive impairment or dementia is present, and (2) determining the disease or diseases that are the cause. But before delving into each of these questions, it will be useful to have a brief discussion of the spectrum of memory changes, both normal and pathological, that can accompany the aging process. The strategy that we are discussing is consistent with the most widely used diagnostic guidelines for Alzheimer’s disease, those from the National Institute on Aging and Alzheimer’s Association (NIA-AA) workgroup ( ; see , for review), and the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) ( ).

The Spectrum of Cognitive Changes

When we discuss the results of a memory evaluation with a patient and family, we often begin with a discussion of the spectrum of memory and other cognitive changes in aging ( Fig. 3-1 ). We note that thinking and memory change just as other abilities do as people age (“Can you run as fast as you could at age 30? Can you still carry heavy boxes of books?”). In general, these age-associated memory changes—those that are part of the typical aging process—are characterized by some reduction in the ability to learn and remember new material (that is, mild changes in recent or short-term memory), as well as difficulty coming up with names of people and places. These changes, although occasionally embarrassing, are generally not considered to be pathological, but rather part of the normal aging process (“senior moments” is one phrase we commonly hear). On the other end of the spectrum are memory deficits that are due to dementing disorders such as Alzheimer’s disease. These changes are not part of normal aging, but rather are due to a disease process. As a disease process, there is a different continuum that is observed with a different trajectory ( Fig. 3-1 ). In any disease process leading to dementia there must be a preclinical phase when it is just starting and no changes are noticeable, a frank dementia stage when functional impairment is prominent, and an in-between stage when mild changes in memory are observed, typically called mild cognitive impairment (MCI). With this as a backdrop, we begin our evaluation of each patient by determining into which of these three categories they fall: age-associated memory changes, mild cognitive impairment, or dementia.

Is Dementia Present?

The first distinction that we endeavor to make is whether the patient meets the criteria for dementia. Dementia is not a disease, but simply a term used to signify the loss of cognitive and functional abilities. Determining that dementia is present requires evaluation of 3 areas: (1) cognition, (2) function, and (3) mood and behavior. These areas are typically evaluated by a combination of interviews with the patient, family, and/or other knowledgeable informant and neuropsychological testing and questionnaires (see Chapter 2 ). Below are the criteria for dementia in DSM-5 (where dementia is referred to as a “Major Neurocognitive Disorder”; Box 3-1 (see Table 2-2 in Chapter 2 for details on the cognitive domains), and from the National Institute on Aging—Alzheimer’s Association workgroup (where dementia from any cause is called “all-cause dementia”; Box 3-2 ).

Box 3-1

DSM-5 Criteria for Major Neurocognitive Disorder

A.

Evidence of significant cognitive decline from a previous level of performance in one or more cognitive domains (complex attention, executive function, learning and memory, language, perceptual-motor, or social cognition) based on:
- 1.
  
  Concern of the individual, a knowledgeable informant, or the clinician that there has been a significant decline in cognitive function; and
- 2.
  
  A substantial impairment in cognitive performance, preferably documented by standardized neuropsychological testing or, in its absence, another quantified clinical assessment.
B.

The cognitive deficits interfere with independence in everyday activities (i.e., at a minimum, requiring assistance with complex instrumental activities of daily living such as paying bills or managing medications).
C.

The cognitive deficits do not occur exclusively in the context of a delirium.
D.

The cognitive deficits are not better explained by another mental disorder (e.g., major depressive disorder, schizophrenia).