Cognitive Screening and Future Directions

Recognizing and preventing mild cognitive impairment as persons age is important. Persons with mild cognitive impairment are more likely to forget to take their medicines, have a greater propensity to falling, have worse outcomes after a major adverse event such as surgery, and die earlier.^[71?73] In addition, approximately a third of persons with mild cognitive impairment will develop Alzheimer disease 3 years after diagnosis.^[74]

In a population-based study of 6,584 participants between ages 55 and 106 years, AF incidence in cognitively impaired persons without dementia was 6%; in those with dementia, it was 13%, both significantly higher than those without cognitive impairment (2.1%).^[75] Atrial fibrillation was the strongest risk factor (odds ratio [OR] 8.1) for cognitive impairment in a small population of patients with congestive heart failure,^[76] it was the only risk factor independently associated with prestroke cognitive impairment,^[77] and its development in patients without previous AF or stroke predicted a faster decline in MMSE scores at mean follow-up of 7 years.^[78] In patients with overt stroke, approximately 30% of all cerebral vascular accidents are "cryptogenic" (mechanism of action is unknown). Recently, the CRYSTAL-AF trial showed that within 6 months of loop recorder implantation, 8.9% of people with prior cryptogenic stroke demonstrated at least 1 episode of AF. With standard monitoring, AF was only detected in 1.4% of people. At 3 years, this gap widened to 30% versus 3%.^[79] Therefore, persons with even mild cognitive impairment should be investigated for the presence of AF given its higher prevalence and prognostic importance. Those with evidence of vascular lesions in the brain may benefit from investigation for the presence of paroxysmal AF with an implantable loop recorder. Previous studies are likely to have underestimated the true prevalence of AF, especially paroxysmal, and newer monitoring technology expands our ability to diagnose and categorize AF. This will require greater awareness and attention to the possibility of occult AF on the part of clinicians, especially in the younger population.

Because of the importance of cognitive impairment, we recommend that all persons with AF be screened for mild cognitive impairment on a yearly basis. Of persons >65 years old, 11.1% have dementia compared to 5.9% of general population, and AF confers a 40% to 50% higher risk of Alzheimer disease and all-cause dementia, independent of stroke.^[80] Although the MMSE has been classically used to screen for dementia, it is a poor tool for diagnosing mild cognitive impairment.^[81] Both the St Louis University Mental Status (SLUMS) examination and the Montreal Cognitive Assessment (MoCA) have excellent sensitivity and specificity for mild cognitive impairment and prediction of outcomes.^[82,83,84] The MoCA takes approximately 10 minutes to perform, and the SLUMS, 7 ½ minutes. Both of these times are too long for a busy clinician to perform. For this reason, we have developed the Rapid Cognitive Screen, which takes 2 ½ minutes to perform and, unlike the MiniCog,^[85] can identify mild cognitive impairment ().^[33]

Date: 2016-06-13; view: 7