Screening for Dementia: Recommendation and Rationale

Summary of the Recommendation The U.S. Preventive Services Task Force (USPSTF) concludes that the evidence is insufficient to recommend for or against routine screening for dementia in older adults. This is a grade I recommendation. (See Appendix Table 1 for a description of the USPSTF classification of recommendations.) The USPSTF found good evidence that some screening tests have good sensitivity but only fair specificity in detecting cognitive impairment and dementia. (See Appendix Table 2 for a description of the USPSTF classification of levels of evidence.) There is fair to good evidence that several drug therapies have a beneficial effect on cognitive function (equivalent to delaying the natural progression of Alzheimer disease from 2 to 7 months), but the evidence of their beneficial effects on instrumental activities of daily living is mixed, with the benefit being small at best. There is insufficient evidence to determine whether the benefits observed in drug trials are generalizable to patients whose disease would be detected by screening in primary care settings. The accuracy of diagnosis, the feasibility of screening and treatment in routine clinical practice, and the potential harms of screening (for example, labeling effects) are also unknown. The Task Force therefore could not determine whether the benefits of screening for dementia outweigh the harms. Clinical Considerations The Mini-Mental Status Examination (MMSE) is the best-studied instrument for screening for cognitive impairment. When the MMSE is used to screen unselected patients, the predictive value of a positive result is only fair. The accuracy of the MMSE depends on a person's age and educational level: Using an arbitrary cut-point may potentially lead to more false-positives among older people with lower educational levels, and more false-negatives among younger people with higher educational levels. Tests that assess functional limitations rather than cognitive impairment, such as the Functional Activities Questionnaire (FAQ), can detect dementia with sensitivity and specificity comparable to those of the MMSE. Early recognition of cognitive impairment, in addition to helping make diagnostic and treatment decisions, allows clinicians to anticipate problems the patient may have in understanding and adhering to recommended therapy. This information may also be useful to the patient's caregivers and family members in helping to anticipate and plan for future problems that may develop as a result of progression of cognitive impairment. Although current evidence does not support routine screening of patients in whom cognitive impairment is not otherwise suspected, clinicians should assess cognitive function whenever cognitive impairment or deterioration is suspected on the basis of direct observation; patient report; or concerns raised by family members, friends, or caretakers. The brief review of the evidence and other sections that are normally included in USPSTF recommendation statements are available in the complete recommendation and rationale statement on the USPSTF Web site (www.preventiveservices.ahrq.gov). Recommendations of Others No formal recommendations for routine screening for dementia are available. The American Academy of Neurology (1) and the Canadian Task Force on Preventive Health Care (2) conclude that there is insufficient evidence to recommend cognitive screening in asymptomatic individuals. The American Medical Association (3) and the American Academy of Family Physicians (4) recommend that physicians be alert for cognitive and functional decline in elderly patients for recognition of dementia in its early stages. Appendix Table 1. U.S. Preventive Services Task Force Grades and Recommendations Appendix Table 2. U.S. Preventive Services Task Force Grades for Strength of Overall Evidence