Evidence-Based Reviews

Subjective cognitive impairment: When to be concerned about ‘senior moments’

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Thorough evaluation can differentiate benign memory problems from dementia


 

References

MS. F, age 66, requests genetic testing because she is concerned about mild memory difficulties, such as forgetting names and where she puts her keys or checkbook, and fears she may be developing Alzheimer’s disease (AD). Her mother and sister were diagnosed with AD in their early 60s. Ms. F has 20 years of education and reports no problems with driving, managing her finances, remembering to take her medications, or maintaining social activities, which her husband confirms.

Detailed questioning about anxiety and depressive symptoms reveals substantial worries about future cognitive decline and some concerns about her finances and her husband’s health. Ms. F says she occasionally feels down and has low energy but denies other depressive symptoms. She reports no sleep disturbances—including snoring and daytime sleepiness, which could indicate obstructive sleep apnea—which her husband confirms. Ms. F takes levothyroxine for hypothyroidism, atenolol for hypertension, aspirin and clopidogrel for coronary artery disease, and atorvastatin for hyperlipidemia. In addition, she provides a long list of over-the-counter (OTC) supplements—ginkgo, huperzine, ginseng, phosphatidylserine, B1, B12, folate, vitamin D, alpha-lipoic acid, and vinpocetine—that she takes to “protect” her brain from AD.

Subjective cognitive impairment (SCI) in older persons is a common condition with a largely unclear prognosis. Many older adults (age ≥65) express concern about mild cognitive problems—“senior moments”—such as word-finding difficulties and forgetfulness.1 Individuals may wonder if walking into a room only to forget why might be the first sign of dementia. Some older adults try to counteract these memory problems by engaging in brain exercises—including costly computer games—and taking OTC “brain-enhancing” vitamins, herbal remedies, and other supplements.

Although some clinicians may view SCI as benign, that is not always true (Table l).2-5 This article discusses the clinical significance of these mild cognitive complaints by examining:

  • age-related cognitive decline (ARCD)
  • SCI
  • how SCI can be differentiated from more serious conditions, such as mild cognitive impairment (MCI) and early stages of AD and other dementias.

We also will discuss assessing and treating cognitive complaints. Although distinctions between SCI and ARCD may be controversial, evidence suggests clinicians need to adopt a more nuanced clinical approach.

Table 1

Why SCI should be taken seriously

SCI may create emotional distress because patients are aware of decline in their ‘mental sharpness’
SCI patients might consume unnecessary and potentially harmful OTC supplements touted to promote memory
Patients might limit their driving and financial management to avoid making mistakes
SCI might impair medication adherence2
SCI may be an early sign of dementia3
Patients’ worry about their self-perceived memory loss might predict dementia4
SCI may predict nursing home placement5
Addressing SCI gives health care providers an opportunity to address anxiety or depression that often accompany SCI
Evaluation of potential causes of SCI may uncover reversible conditions that can be treated
OTC: over-the-counter; SCI: subjective cognitive impairment

‘Normal’ cognitive decline

ARCD is subtle decline in cognitive abilities, such as episodic memory, attention, and time needed to complete complex activities.6,7 Individuals with ARCD might not have subjective memory complaints or objective cognitive deficits, and their ability to live independently may not be compromised.7 The degree of decline in ARCD may be smaller than previously thought.8 Park9 summarizes 4 main mechanisms thought to underlie age-related declines in cognition:

  • reduced speed of processing
  • decreased working memory capabilities
  • declining inhibitory control (eg, impaired complex attentional capabilities)
  • sensory changes (eg, visual and auditory deficits).

ARCD traditionally is thought to result from predictable changes in the brain associated with aging, such as reduced brain volume in the hippocampus and frontal lobes, loss of myelin, loss of synapses, and cytoskeletal changes.7 However, not all older adults experience ARCD. Some remain highly functional in their later years and continue to actively engage in life well into very old age.6,9

Subjective cognitive impairment

One-quarter to one-half of community-dwelling older adults report subjective cognitive complaints, such as forgetfulness and word-finding difficulties.10 Patients with SCI do not show objective evidence of cognitive impairment on neuropsychological tests and their cognitive problems cause no functional decline.10

Preliminary evidence indicates that SCI may be a harbinger of further cognitive decline. Reisberg et al3 found that compared with patients without SCI, patients with SCI were 4.5 times more likely to develop MCI—cognitive difficulties that can be detected by cognitive tests, but do not cause functional decline—or dementia within 7 years.3 Studies also have suggested that SCI may be a pre-MCI stage of subsequent dementia.11-13 AD generally has a long (10 to 12 years) and progressive prodromal phase before dementia onset and is characterized by successive emergence of cognitive deficits, memory complaints, depressive symptoms, and functional impairment.14

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