Cognitive Performance Test Update

By Theressa Burns, OTR

The Cognitive Performance Test (CPT) was initially developed as a research instrument to provide a baseline measure of global function in individuals with Alzheimer’s disease (AD) and to track change over time. Currently, the test is used in clinics, long term care, and in the home; and with other dementia and geropsychiatric diagnoses, CVA, and TBI patients. Based on Allen’s ordinal scale of function, CPT total scores represent the cognitive levels delineated by the model. The original test uses six common daily living tasks, for which the information-processing requirements can be systematically varied. A gross level score is obtained for each task; these scores are then added and averaged to determine the cognitive level and mode.

Recently, a new subtask titled “medbox” was added. Increasingly, the issue of patient capacity to safely manage medications is of concern, and is identified nationally as an area for quality improvement. Adverse drug events, medication underadherance and noncompliance are common problems, and in Geriatrics are associated with poor cognition, dementia, living alone, and having three or more medications. As with the other CPT subtasks, although the patient’s cognitive level is used to predict and explain actual performance, an objective measure of competency with a medication task offers face validity for the referring physician, family, and patient.

The “medbox” task requires the patient to follow directions on four bottles of dummy medications (beads) and set-up two pillboxes accordingly, for one week. The bottle directions vary in complexity and two pillboxes are used to add complexity to the task. In addition to assessing the ability to follow medication directions, administration of the task involves giving cues to assess ability to identify inaccurate set-up and correct errors; and reducing the number of bottles and complexity of the task at lower cognitive levels. Studies of the medbox task show a significant difference in performance between normal control subjects and subjects with a dementia diagnosis, and correlation with the other subtasks and CPT total score.

CPT total scores have been found through empirical study to be predictive of functional capacities and needs of patients. For example, with respect to managing medications, persons who function in level 5 can often manage their medications if a routine has been well established, or the management is simple, or there is room for error (can miss pills), or a compensatory strategy is in place. Caregivers may be needed to monitor compliance or to provide reminders. Persons who function in level 4 require close monitoring of medications, and depending on the complexity of the regime, usually require set-up or restriction or reminders to day-to-day supply. Compensatory strategies are often ineffective in mid to low level 4, as the capacity to learn and follow plans is significantly impaired. Persons who function in levels 3, 2, or 1 are not competent to manage any medications. Medications need to be given and access restricted.

Studies of the CPT demonstrate that administering less than 4 subtasks skews the total score, as there are not enough performances to average. This author typically administers all 7 subtasks in about 45 minutes, since her population has very mild to moderate cognitive disability. Patients who live in restricted settings where safety is much less of a concern, may only need to perform portions of the test. Administration in the home does not allow for using the full test, since the DRESS and TRAVEL subtasks are not portable. However, it is feasible to use the remaining 5 tasks in the home, with standard props that the therapist brings in and sets-up according to the protocols. In response to the need for more portable props, an alternative to using belts in the SHOP subtask has been developed; the administration protocol is the same but gloves are used instead. The updated CPT manual includes these new revisions.

Original studies of the CPT were initiated in 1991 at the Minneapolis Geriatric Research, Education, and Clinical Center (GRECC), as part of a National Institute of Aging longitudinal study of AD. The test was found to be valid and reliable and findings are reported in the Journals listed in the reference section of the manual.

Recently, the CPT has been compared to Neuropsychological Assessment. Bares (1998) retrospective study of AD patients who were evaluated in the GRECC found significant relationships between performance on the CPT and on neuropsychological measures. The sample included 100 mostly male, Caucasian patients aged 59 or older with mild to moderate stage disease. The average age was 74.9 years. In a hierarchical regression analysis of neuropsychological variables predicting function as measured by the CPT, significant predictors were neuropsychological measures that involved psychomotor skill with a planning, sequencing, and attentional component, while measures of memory, language, background variables and comorbidity were not predictive of function. Neuropsychological predictors of performance on the CPT were characterized under the rubric of executive function.

Other analyses showed the CPT subtasks were highly related to each other. The CPT was found to have high internal consistency reliability (a = .76), which is comparable to although somewhat lower than the previous finding of .84. Factor analysis of the six CPT subtests supported the Burns et al. conclusion that the tasks are nonspecific, and reflect a single construct characterized as global functional status rather than discrete functional living skills. Findings support the conclusion that the CPT total score, not the individual tasks should be used.

Jennings-Pikey (2001) conducted similar studies of the relationship between neuropsychometrics and the CPT. One hundred eleven inpatient records from an inpatient psychiatric hospital in the Upper Midwest were accessed for study through archival records. The sample was mostly female and Caucasian, average age was 79.6 years, and 61% of subjects received a primary diagnosis of dementia or memory loss. There was a significant difference on the CPT between the means of the group that was given a memory loss diagnosis and those who did not receive this diagnosis, demonstrating that people with a memory loss diagnosis functioned at a lower level on the CPT. The validity of the CPT was supported to the extent that the test showed significant correlations with measures known to be sensitive to cognitive functioning in older adults. Convergent validity was demonstrated with significant correlation to the Global Assessment of Functioning (GAF) and the internal structure of the CPT to measure competency to carry out independent living skills was upheld.