Our goals in developing the CAMCI were to use current cognitive criteria for MCI29
to develop a test that is self-administered, user-friendly, scores automatically, and can be completed in a quiet space (eg, doctor’s examination room) to provide a score that represents the probability that the individual’s cognitive performance would fall within the range of MCI if tested on a comprehensive neuropsychological test battery and reviewed by expert neuropsychologists. Our results indicated that the CAMCI successfully identified elderly nondemented patients with MCI and was more effective compared with the MMSE.
Decline in everyday memory is an indicator of MCI and impaired performance on standard neuropsychological tests of memory was one of the criteria used to identify MCI. Therefore, it is not surprising that the CRT analysis identified performance on tests of verbal and visual memory (both free recall and recognition) as 2 of the most important variables. Reaction time was also identified as an important variable, suggesting that individuals with MCI may make correct responses but take longer to do so. Also, performance on 2 of the shopping trip tasks entered into the CRT analysis at an early stage, levels 2 and 3, indicated that performance on this ecologically valid assessment can also be used as an indicator of MCI.
A MMSE cut-off of 28 provided the best sensitivity and specificity (45% and 80%, respectively) for identification of MCI but this was considerably poorer than the rates observed using the CAMCI. Our findings suggest that the MMSE is insensitive at the upper end of the range of cognitive abilities and does not identify individuals with the very mildest, earliest signs of cognitive problems.
One important limitation of this study is the absence of a reliable informant to determine the classification of MCI. The use of proxies to provide information about the participant’s cognitive and functional abilities is helpful because self-reporting may not be reliable, particularly among cognitively impaired individuals. Another limitation is the possibility that individuals > 65 years have limited experience using computers and may be reluctant to try the test. However, that was not our experience in this study. Only 3 of the original samples of 581 individuals recruited for the study failed to complete the test. The majority of elderly patients were enthusiastic in their response to using the computer. The current literature on computer use by the elderly suggests that older Americans are increasingly relying on computers for communication, purchases, and searching for information and suggests that print size must be adequate, they must be able to self-pace, have the opportunity to practice, and the presentation of material must be highly organized with visual displays that are simple and relevant to the task.31–33
The CAMCI satisfies these conditions and the patient both sees and hears the instructions to increase comprehension and reduce the possibility of errors from sensory impairment. The touch-screen tablet computer is no more complex than a phone or automatic teller machine (ATM) keypad. As the baby-boom generation ages, more elderly individuals will have had routine experience with computers in the workplace and at home.
The community sample was older and less well educated than the PCP sample. The demographic differences in the 2 samples represent the normal range of variance in the elderly population and ensure that the total sample in this study was more representative of the community at large than either sample would be individually. Furthermore, each individual was clinically adjudicated as either having normal or impaired cognition taking into account demographic characteristics.
Our sample included a higher percentage of individuals with MCI than typically found in the general population. For example, Meguro et al34
reported a 30.2% overall frequency of MCI. There are 2 possible reasons for this finding. First, it was not an epidemiological study. Primary care physicians were more likely to refer individuals who they had concerns about than those they thought had normal cognition, and the senior citizens centers from which the community sample was recruited probably included a disproportionately large number of frail elderly patients. Second, currently accepted criteria for differentiating MCI from dementia and normal cognition from MCI are evolving. They are imperfect and the neuropsychological cut-off for cognitive impairment used in this study, 1 SD below age norms, is more liberal than suggested by some researchers.29,35–38
This may have resulted in more individuals with normal cognition being included in the cognitively impaired group than would be the case using other criteria. However, application of the neuropsychological criteria was only the first stage of the review process and many individuals with neuropsychological test scores within this range would not have been given a final classification of MCI once the expert panel reviewed the demographic, medical, psychiatric, and functional data. Using this higher cut-off point allowed us to include individuals who are often missed from studies employing lower cut-off points (ie, those highly educated, high-functioning individuals who have subjective complaints and may have declined from a previously higher level but not met a lower cut-off). As with the results of a comprehensive neuropsychological evaluation, performance on the CAMCI alone does not determine the etiology of a cognitive impairment and performance on the CAMCI is only 1 indicator. The physician should determine the validity of the score, the need for further investigation, and the final etiology of the deficit.
We recognize that many clinicians are reluctant to subject patients to tests of cognitive functioning fearing that some will become despondent, leading to increased rates of depression. With no currently available effective screening test for determining MCI leading to AD, widespread screening in PCP offices has not been proven to be cost-effective. However, proponents of screening believe that a quick and easy test would capture a baseline assessment against which future cognitive changes could be compared, assuming an effective treatment will become available. Some propose only screening patients who are reporting noticeable memory problems in everyday life. However, not all impaired elderly patients report cognitive decline.39
Our goal in developing the CAMCI was not to develop a test to diagnose early AD or other cognitive disorders, but rather to develop a test that reliably reproduces the results of an expert interpretation of a comprehensive neuropsychological test battery without the attendant time burden or the need for expertise of administration, scoring, and interpretation. We envisage that the CAMCI will be an addition to the currently available tests and that PCPs will be able to use it for determining the presence or absence of cognitive difficulties as readily as they test for the presence of vascular risk factors, heart disease, or metabolic disease.