Recovery of cognitive function after coronary artery bypass graft operations

The effect of coronary artery bypass grafting (CABG) operations on cognition was examined after controlling for the operation, emotional state, preexisting cognitive impairment, and repeated experience with cognitive tests.

On-pump CABG patients (n=16), thoracic surgical patients (n=15), and a nonsurgical control group (n=15) were tested preoperatively, and at 1 and 8 weeks postoperatively, using a battery of cognitive tests and an emotional state assessment. Patient groups were similar in age, sex, level of education, and premorbid intelligence quotient score. Surgical group data were normalized against data from the nonsurgical control group before statistical analysis.

CABG patients performed worse on every subtest before the operation, and this disadvantage persisted after the operation. Anxiety, depression, and stress were associated with impaired cognitive performance in the surgical groups 1 week after the operation: 44% of CABG patients and 33% of surgical control patients were significantly impaired; yet, by 8 weeks, nearly all patients had recovered to preoperative levels, with 25% of CABG and 13% of surgical control patients improving beyond their preoperative performance.

Stress, anxiety, and depression impair cognitive performance in association with CABG and thoracic operations. Most patients recover to, or exceed, preoperative levels of cognition within 8 weeks. Thus, after controlling for nonsurgical factors, the prospects of a tangible improvement in cognition after CABG are high.