Recommendations on screening for cognitive impairment in older adults.

As people age, changes to the structure and the function of the brain may result in cognitive decline. These changes, however, do not equally affect all cognitive domains or all people. Older adults may perform as well as younger adults in some or all cognitive domains, and some may even perform better.1 The most common cognitive functions affected by age are memory and perception, which in some cases may have an impact on more complex cognitive functions such as decision-making and language.1 Cognitive impairment occurs in a continuum, starting with aging-related cognitive decline, transitioning to mild cognitive impairment and ending with dementia. Mild cognitive impairment is noticeable but does not substantially affect daily function, whereas dementia involves cognitive changes that are severe enough to affect daily function.2,3 Although some people with mild cognitive impairment may be at higher risk of dementia than others with the diagnosis, over time some will remain stable and a few will show improvements in their cognitive abilities.1 The incidence of dementia among Canadian adults aged 65–79 years is 43 per 1000 population and rises with age (to 212 per 1000 among those aged 85 or older).4 The reported prevalence of mild cognitive impairment varies because of several factors, such as the diagnostic test score (i.e., cut-off) used to define mild cognitive impairment, age at the initial assessment and length of follow-up.5 Published Canadian cohort prevalence rates for mild cognitive impairment are not available. Studies from the United States have reported prevalence ranging from 9.9% to 35.2% among adults aged 70 or older.6–8 Cognitive impairment is commonly assessed using screening tools such as the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA) and the cognitive subscale of the Alzheimer’s Disease Assessment Scale (ADAS-cog).9–11 The MMSE has a raw score range of 0 to 30 and typically uses a cut-off of scores below 23 to suggest likely cognitive impairment,12 although the specific cut-off that is recommended varies based on age and education level.11 Clinical significance is considered to be a change in score of 1.4 to 3 points. A systematic review11 reported that a large body of studies suggested a general cut-off between 23 and 24 or between 24 and 25 to screen for dementia, which could be appropriate for most primary care populations. The review also reported a cut-off of 27 or 28 points for MMSE to detect mild cognitive impairment (with a low and wide range of sensitivity rates).11 However, these reported cut-offs were based on a limited subset of studies that used different definitions and had different prevalence rates of underlying mild cognitive impairment. The MoCA is also scored out of 30 and provides interpretive guidance as follows: mild cognitive impairment (scores of 18–26), moderate Recommendations on screening for cognitive impairment in older adults