Improved brief assessment of cognition in aging and dementia.

To enhance the score interpretation and practicality of the Cambridge Cognitive Examination (CAMCOG) neuropsychological test, the authors used item response theory (IRT) to calibrate the difficulty of the items using the scores of 797 subjects. Forty-seven items fitted the IRT model. Score agreement with equally difficult short forms was excellent. The practicality and interpretability of the CAMCOG was improved, while the diagnostic accuracy of the short forms was similar to that of the original 60-item instrument.