Validation of reaction time as a measure of cognitive function and quality of life in healthy subjects and patients.

OBJECTIVE

Malnutrition is a common problem in hospitalized patients and is related to decreased cognitive function and impaired quality of life (QoL). We investigated the validity of reaction time as a simple bedside tool for measuring cognitive function in healthy subjects and patients, and additionally the relationships with QoL and malnutrition in patients.

METHODS

Healthy subjects (N = 130) were assessed for simple and complex reaction time and cognitive function (Addenbrooke cognitive examination, ACE). Patients (N = 70) were assessed for simple and complex reaction time, cognitive function (ACE), and QoL (short-form health survey) (N = 40).

RESULTS

Reaction time was related to cognitive function in both healthy subjects and patients. Reaction time was inversely related to the physical component summary of QoL in patients (r = -0.42, P < 0.001). Five of eight QoL scales and the mental component summary of QoL were significantly lower in malnourished patients. Reaction time and ACE were impaired in patients compared to healthy subjects, but not further impaired in malnourished patients.

CONCLUSION

Simple reaction time test is related to cognitive function in healthy subjects and patients and to QoL in patients. Complex reaction time test is related to more components of cognitive function. Thus, simple and complex reaction time tests could serve as bedside measurements reflecting, respectively, QoL or cognitive function.