Am Fam Physician. 2004;69(6):1473-1475
This statement summarizes the U.S. Preventive Services Task Force (USPSTF) recommendations on screening for dementia and the supporting evidence, and it updates the 1996 recommendations contained in the Guide to Clinical Preventive Services, second edition.1 Explanations of the ratings and of the strength of overall evidence are given in Tables 1 and 2, respectively. The full USPSTF recommendation and rationale statement on this topic, which includes a brief review of the supporting evidence, is available through the USPSTF Web site (http://www.ahrq.gov/clinic/uspstfix.htm) and the National Guideline Clearinghouse (http://www.guideline.gov). The complete information on which this statement is based, including evidence tables and references, is available in the summary of the evidence2 and the systematic evidence review3 at the Agency for Healthcare Research and Quality Web site noted above. The summary of the evidence and the recommendation statement are also available in print by subscription through the AHRQ Publications Clearinghouse (telephone, 1–800–358–9295 or e-mail,ahrqpubs@ahrq.gov).
The USPSTF recommendations are independent of the U.S. government. They do not represent the views of the AHRQ, the U.S. Department of Health and Human Services, or the U.S. Public Health Service.
| The USPSTF grades its recommendations according to one of five classifications (A, B, C, D, or I) reflecting the strength of evidence and magnitude of net benefit (benefits minus harms). | |
| A. | The USPSTF strongly recommends that clinicians provide [the service] to eligible patients. The USPSTF found good evidence that [the service] improves important health outcomes and concludes that benefits substantially outweigh harms. |
| B. | The USPSTF recommends that clinicians provide [the service] to eligible patients. The USPSTF found at least fair evidence that [the service] improves important health outcomes and concludes that benefits outweigh harms. |
| C. | The USPSTF makes no recommendation for or against routine provision of [the service]. The USPSTF found at least fair evidence that [the service] can improve health outcomes but concludes that the balance of benefits and harms is too close to justify a general recommendation. |
| D. | The USPSTF recommends against routinely providing [the service] to asymptomatic patients. The USPSTF found at least fair evidence that [the service] is ineffective or that harms outweigh benefits. |
| I. | The USPSTF concludes that the evidence is insufficient to recommend for or against routinely providing [the service]. Evidence that [the service] is effective is lacking, of poor quality, or conflicting, and the balance of benefits and harms cannot be determined. |
| The USPSTF grades the quality of the overall evidence for a service on a three-point scale (good, fair, or poor). | |
| Good: | Evidence includes consistent results from well-designed, well-conducted studies in representative populations that directly assess effects on health outcomes. |
| Fair: | Evidence is sufficient to determine effects on health outcomes, but the strength of the evidence is limited by the number, quality, or consistency of the individual studies; generalizability to routine practice; or indirect nature of the evidence on health outcomes. |
| Poor: | Evidence is insufficient to assess the effects on health outcomes because of limited number or power of studies, important flaws in their design or conduct, gaps in the chain of evidence, or lack of information on important health outcomes. |
Summary of Recommendation
The USPSTF concludes that the evidence is insufficient to recommend for or against routine screening for dementia in older adults. I recommendation.
The USPSTF found good evidence that some screening tests have good sensitivity but only fair specificity in detecting cognitive impairment and dementia. 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’s disease from two to seven 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 (e.g., labeling effects) are also unknown. The USPSTF therefore could not determine whether the benefits of screening for dementia outweigh the harms.
Clinical Considerations
The Mini-Mental State 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-positive results among older people with lower educational levels and more false-negative results among younger people with higher educational levels. Tests that assess functional limitations rather than cognitive impairment, such as the Functional Activities Questionnaire, can detect dementia with sensitivity and specificity comparable to that of the MMSE.
Early recognition of cognitive impairment, in addition to helping make diagnostic and treatment decisions, allows clinicians to anticipate problems patients may have in understanding and adhering to recommended therapy. This information also may 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, based on direct observation, patient report, or concerns raised by family members, friends, or caretakers.
The Scientific Evidence and Recommendations of Others sections that are usually included in USPSTF recommendation statements are available in the complete Recommendation and Rationale statement on the USPSTF Web site (http://www.ahrq.gov/clinic/uspstfix.htm).