Finding our way from the heart to the head.

See related articles on pages 1061 and 1087. W e have all had this experience. The patient sits before us accompanied by a family member during a preoperative office visit, denying any cognitive problems after a significant cardiac event. The gestures from the family member in the background of the office indicate something quite different. “Oh no, I’m doing fine,” the patient says, despite occupational, financial, social, and sexual dysfunction. However, when we ask about the children and grandchildren, the room suddenly becomes humid. So, what is all the concern about any relationship between the head and the heart? According to our patient, there is not any. If we are to explain this cardiocognitive connection, much will depend on further exploration of physiologic parameters and not just new surgical techniques. Neuropsychology can further the contribution to cardiothoracic surgery in this area. Balancing variable selection, design, statistical manipulation, and assessment of the relevant outcome is a tough accomplishment. The current article by Taggart and colleagues does just that, isolating a variable, blood gas levels, to assess the relationship between preoperative and postoperative cognitive dysfunction. Use of parametric statistics over incident reports, frequency, or descriptive statistics alone carries more power in assessing clinical outcome and applicability. Parametric analyses with an established confidence level at a P value of less than .05 or less than .01 will assist interpretation. Most medical research accepts results at a P value of less than .05. The use of standardized scores, z scores, allows researchers to compare measures over time. Investigators usually establish an interpretation of clinically meaningful change a priori. The use of standardized scores, patient self-reports, and collateral data from family members or significant others will help to convey clinically meaningful information. Studies do establish a 1 to 1.5 SD of change as significant. Others accept a 20% difference within 20% of the tests administered and with given control group comparisons. A 20% of 20% formula works well if the battery is comprehensive. With abbreviated batteries, we risk the overacceptance of minimal change. A 2-SD change strengthens conclusions. If we reject the null hypothesis when it should actually be accepted, we are risking a type I error. Conversely, if we accept the null hypothesis and it should be rejected, we are risking a type II error. An acceptable confidence level established before the research study governs the acceptance or rejection of the null hypothesis. It is most important to gear the project design to prevent a type I error. Establishing strict confidence levels, controlling for confounding variables, and obtaining a large heterogeneous sample size strengthens the cardiocognitive connection. The growing interest in neurobehavioral implications associated with cardiac illness and neuroprotective procedures over the past decade has expanded the need for cognitive testing before and after cardiovascular surgery. Recommendations for the inclusion of neuropsychological testing with cardiovascular research have been established. These recommendations include the following: (1) perform preoperative and postoperative cognitive testing; (2) avoid immediate postoperative measures because of the influence of physiologic and pharmacologic effects; and (3) analyze individual differences in performance rather than group differences. Although these recommendations have been accepted, differences still exist from center to center in the selection of cognitive measures, the appropriate timing of From MCP Hahnemann University, Philadelphia, Pa.