IMPACT OF COCHLEAR IMPLANTATION ON COGNITIVE FUNCTIONS OF OLDER ADULTS: PILOT TEST RESULTS

In Reply: The Huber and Kaiser (1) have asked for clarification on drop-outs of participants over the course of the study and the statistical methods. From the original 23 cochlear implant candidates (CIC) in the control group, 9 participants received implants after 6 months and had to be excluded from the study. Ethically, when these candidates have an opportunity to receive an implant, their surgery cannot be delayed because of participation in a research project. Both CIC (n = 23, mean age (M) = 69.04 ± 12.35) and cochlear implant recipients (CIR) (n = 16, M = 61.75 ± 15.62 yr) completed baseline and 6 month assessments. Of the 16 CIR, 5 participants were unavailable for the 12-month assessment (as noted in Table 1) but still remained in the study. Study sample was approximately normally distributed and Leven's test of equality of variances was met; hence, independent sample t test was used. Nevertheless, as requested by Huber and Kaiser (1), a nonparametric independent sample Mann–Whitney U test was conducted. Baseline to 6 month difference scores obtained by both the CIC and CIR groups revealed a significant difference on spatial working memory (SWM)-between error scores (p = 0.04). The participant groups revealed a baseline-12 months significant difference on attention switching task mean correct latency (p = 0.02), paired associates learning total errors adjusted (p = 0.01), reaction time simple accuracy score (p = 0.003), SWM between errors (p = 0.006), SWM between errors 4–8 boxes (p = 0.03), SWM strategy (p = 0.01), and stress (p = 0.01). The significant findings in our published manuscript are thereby confirmed. We agree with the LEAs that the education contributes to cognitive functions. In this study, premorbid intelligence quotient scores of participants calculated using the National Adult Reading Test-Revised (2) were taken into account during the analysis of the Cambridge neuropsychological test automated battery cognitive assessments (3). As both control and experimental groups completed the assessments three times during the course of the study, we assumed that the practice effect could have equally affected both participant groups. We agree that due to high standard deviations and confidence intervals of the stress scores, the results should to be interpreted with caution, however, as we indicated in the title of our study, this is a pilot study and results need to be treated as such. Finally, we appreciate the points raised by Huber and Kaiser (1), but we stand by our results that improved hearing and speech perception scores observed in implant recipients could have contributed to changes observed in cognitive and mental health functions of CIR compared with the CIC. Similar findings on improved cognitive functions following cochlear impanation have been reported by other research groups (4,5).