USPSTF finds insufficient evidence to recommend routine screening for cognitive decline

The U.S. Preventive Services Task Force (USPSTF) found insufficient evidence to recommend routine screening with formal screening instruments for cognitive decline in adults over the age of 65 in the primary care setting who have no signs of impairment.

To update its recommendations, the USPSTF commissioned a systematic review of the evidence on screening for cognitive impairment, including dementia and mild cognitive impairment. The Task Force findings appear in the March 25 Annals of Internal Medicine.

Although the Task Force found details on routine screening insufficient, they also identified important reasons to identify early cognitive impairment:

• to help patients make diagnostic and treatment decisions, such as treatment of reversible causes and management of comorbid conditions;
• to allow clinicians to anticipate problems patients may have in understanding and adhering to recommended therapy; and
• to allow patients and their caregivers and family members to anticipate and plan for future problems.

Despite the insufficient evidence, clinicians should remain alert to early signs or symptoms of cognitive impairment (for example, problems with memory or language) and evaluate them, the review stated. The National Institute on Aging has information on the detection and management of cognitive impairment for patients and clinicians, including a database of tools to detect cognitive impairment online.

In 2003, the USPSTF concluded that the evidence was insufficient to recommend for or against routine screening for dementia in older adults. The current evidence review found much more information on the test performance of screening instruments than in 2003, and the Task Force concluded that there is now adequate information on the test performance of some screening tools, the report stated.

The Mini-Mental State Examination was the most widely published, with 25 studies. It is a 30-point instrument with 11 items. For the most tool's commonly reported cut points (23/24 or 24/25 [score considered “positive”/”negative”]), the pooled sensitivity from 14 studies involving 10,185 participants was 88.3% (95% CI, 81.3% to 92.9%) and specificity was 86.2% (95% CI, 81.8% to 89.7%). Other instruments, such as the Clock Drawing Test, verbal fluency tests, or Informant Questionnaire on Cognitive Decline in the Elderly, were reviewed by 4 to 7 studies each, had limited reproducibility in primary care-relevant populations, and had unknown optimum cut points. Sensitivity and specificity ranged widely, the report stated.

Similar to the findings of the 2003 evidence review and recommendation, the USPSTF found that pharmacologic treatments result in small benefits of unknown clinical significance. The review identified more than 130 studies on several interventions for managing or treating mild to moderate dementia, including pharmacologic and nonpharmacological interventions.

Pharmacologic interventions included FDA-approved medications for the treatment of Alzheimer's disease with the purpose of preventing or delaying cognitive impairment. Acetylcholinesterase inhibitors and memantine improved global cognitive function by approximately 1- to 3-point differences on the Alzheimer's Disease Assessment Scale–Cognitive Subscale (ADAS-cog). A meta-analysis of 7 rivastigmine trials reported a 3-point difference on the ADAS-cog (−3.06; [95% CI, −4.48 to −1.65]; I²=92.6%).

Only 4 trials were done in patients with mild cognitive impairment and reported global cognitive function. Trials of donepezil and galantamine generally showed a small but unclear clinical effect on global cognitive function, the report stated.