THE IMPORTANCE OF EARLY DETECTION AND DIAGNOSIS OF
MILD COGNITIVE IMPAIRMENT DUE TO ALZHEIMER’s DISEASE

Pathophysiological changes due to Alzheimer’s disease (AD) may occur many years before symptoms appear. Mild cognitive impairment (MCI) due to AD provides a potential window to detect and diagnose Alzheimer’s disease before significant neurodegeneration has begun. Yet, Alzheimer’s disease remains underdiagnosed and underreported.1-3

MCI due to AD is the earliest stage when symptoms may be evident4

Patients who are clinically diagnosed during this early stage can be accurately diagnosed 92% of the time. Alzheimer’s disease biomarkers may provide proof of the underlying cause.4

Alzheimer’s Disease Continuum With Stages for Early Detection Highlighted5,6

Horizontal Animated Icons that illustrate progressions of Alzheimer's Disease Vertically Animated Icons that illustrate progressions of Alzheimer's Disease

Recognition of MCI due to AD is low, despite a high prevalence of Alzheimer’s disease

Studies show that cognitive impairment may remain unrecognized in up to 80% of affected patients in primary care.7 However, among patients with cognitive impairment, 60% to 80% have Alzheimer’s disease.5

Understanding and overcoming barriers to early diagnosis

Low recognition of Alzheimer’s disease may be caused by several barriers, including:

Improving cognitive functions

The time burden associated with testing and counseling7

Treating depression

Reluctance of patients and care partners to report signs or symptoms due to stigma around Alzheimer’s disease7

Delaying institutionalization

Lack of diagnostic resources8

Early diagnosis includes assessing impairments beyond memory

In-depth investigation of multiple domains is necessary, since 16% of MCI patients have no memory impairment and many MCI patients present with multiple cognitive domains affected.9

Because other cognitive domains can be impaired among individuals with MCI, it is important to examine domains in addition to memory3:

Executive functions

(eg, set-shifting, reasoning, problem-solving, planning)3,7

Visuospatial skills

(eg, visual perception, perceptual-motor coordination)3,7,10

Attentional control

(eg, simple and divided attention)3,7

Language

(eg, naming, fluency, expressive speech, and comprehension)3,7

Brief cognitive assessments may help identify patients with MCI

Evidence of progressive cognitive decline is essential for accurate diagnosis and treatment. While no test represents a “gold standard,” use of brief cognitive assessment tools with appropriate patients can aid in the early identification of MCI and mild dementia.3,7 Screening assessments will vary based on clinical practice settings and patient response.

Brief dementia screening tools include (but are not limited to)7,12:

  • MMSE (Mini-Mental State Examination)
  • AMTS (Abbreviated Mental Test Score)
  • Clock Drawing Test
  • 6-CIT (6-Item Cognitive Impairment Test)
  • GPCOG (General Practitioner Assessment of Cognition)
  • TYM (Test Your Memory)
  • MoCA (Montreal Cognitive Assessment)
  • ACE-R (Addenbrooke’s Cognitive Examination – Revised)
  • MIS (Memory Impairment Screen)

These tests can generally be administered in 3 to 20 minutes.12

References

  1. Alzheimer’s Association. Alzheimer’s Association Report: 2018 Alzheimer’s disease facts and figures. Alzheimers Dement. 2018;14:367-429.
  2. Petersen RC. Mild cognitive impairment. Continuum (Minneap Minn). 2016;22(2):404-418.
  3. Albert MS, DeKosky ST, Dickson D, et al. The diagnosis of mild cognitive impairment due to Alzheimer’s disease: recommendations from the National Institute on Aging–Alzheimer’s Association workgroups on diagnostic guidelines for Alzheimer’s disease. Alzheimers Dement. 2011;7(3):270-279.
  4. Morris JC, Blennow K, Froelich L, et al. Harmonized diagnostic criteria for Alzheimer’s disease: recommendations. J Intern Med. 2014;275(3):204-213.
  5. Alzheimer’s Association. Alzheimer’s Association Report: 2020 Alzheimer’s disease facts and figures. Alzheimers Dement. 2020;16(3):391-460.
  6. Food and Drug Administration; US Department of Health and Human Services. Early Alzheimer’s disease: developing drugs for treatment, guidelines for industry. Draft guidance: February 2018. www.fda.gov/media/110903/download. Accessed February 20, 2020.
  7. Cordell CB, Borson S, Boustani M, et al; and Medicare Detection of Cognitive Impairment Workgroup. Alzheimer’s Association recommendations for operationalizing the detection of cognitive impairment during the Medicare Annual Wellness Visit in a primary care setting. Alzheimers Dement. 2013;9(2):141-150.
  8. Galvin JE, Sadowsky CH; NINCDS-ADRDA. Practical guidelines for the recognition and diagnosis of dementia. J Am Board Fam Med. 2012;25(3):367-382.
  9. Lopez OL, Becker JT, Jagust WJ, et al. Neuropsychological characteristics of mild cognitive impairment subgroups. J Neurol Neurosurg Psychiatry. 2006;77(2):159-165.
  10. Sachdev PS, Blacker D, Blazer DG, et al. Classifying neurocognitive disorders: the DSM-5 approach. Nat Rev Neurol. 2014;10(11):634-642.
  11. Petersen RC, Lopez O, Armstrong MJ, et al. Practice guideline update summary: mild cognitive impairment: report of the Guideline Development, Dissemination, and Implementation Subcommittee of the American Academy of Neurology. Neurology. 2018;90(3):126-135.
  12. Sheehan B. Assessment scales in dementia. Ther Adv Neurol Disord. 2012;5(6):349-358.

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