Patients with mild cognitive impairment (MCI) are by definition still autonomous in daily life and therefore make their own decisions, for example, concerning their own or their partners' health care. Health care information typically contains complex mathematical constructs like proportions, probabilities, and survival rates. The purpose of this study was to investigate whether patients with MCI have difficulties with understanding health numeracy questions and to explore the impact of declining cognitive functions. The performance of 25 patients with MCI in a health numeracy questionnaire was compared with the performance of a control sample including 164 healthy older adults, matched in age and educational level. Participants were asked to convert percentages, assess different probabilities, or understand the dosage of a short patient information leaflet. Additionally, neuropsychological background tests were administered. Patients with MCI answered fewer items correctly than controls in the health numeracy questionnaire. A correlation analysis showed statistically significant associations between performance in the health numeracy task and mental arithmetic, executive functions (psychomotor speed, conceptualization), and global cognitive status, respectively. Patients with MCI show problems in understanding numerical information concerning health care. Since patients with MCI are confronted with several health care decisions, special attention has to be paid to presenting information in an easily understandable way, to make additional sources of information available, and to provide adequate support.
Keywords: Advanced age; cognition; decision making; health numeracy; mental arithmetic; mild cognitive impairment.