Preliminary evidence of impaired thinking in sick patients.

BACKGROUND: Earlier anecdotal observations suggested to us that certain aspects of judgment in sick adults approximate the thinking of children.
OBJECTIVE: To describe changes in judgment associated with serious illness in otherwise competent adults.
DESIGN: Cohort study.
SETTING: Urban acute-care hospital and senior citizen center. PARTICIPANTS: Sicker (Karnofsky score </= 50; n = 24) and less sick (Karnofsky score > 50; n = 39) hospitalized patients were compared with controls (n = 28). Normal performance on the Mini-Mental State Examination (score >/= 24) was required for study entrance. MEASUREMENTS: Seven Piagetian tasks of judgment designed to study childhood cognitive development. Degree of sickness was determined by using the Karnofsky scale of physical function.
RESULTS: Patients with Karnofsky scores of 50 or less responded correctly to fewer Piagetian tasks than controls (mean [+/-SD], 1.8 +/- 2.6 vs. 5.9 +/- 1.6; P < 0.001). Furthermore, a smaller proportion of sicker patients responded correctly to each of the seven tasks. Patients with Karnofsky scores greater than 50 did not perform differently than controls.
CONCLUSION: In sicker hospitalized patients, performance on seven Piagetian tasks of judgment was similar to that among children younger than 10 years of age. This evidence of cognitive impairment warrants further investigation.