Event‐related potential and neuropsychological function in depressed older adults with cognitive impairment: A correlational study

BACKGROUND: Increased depression severity has been linked to cognitive functioning impairment, such as deficits in episodic memory and executive function, causing difficulties in planning strategies, which ultimately lead to impaired decision‐making functions. There are number of ways to assess cognitive functions, two most important and routinely done tests are neuropsychological test battery (NBT) and event‐related potentials (ERPs). OBJECTIVE: This study examines the relationship between conventional neuropsychological tests assessing various cognitive domains and an ERP‐P300 in depressed older adults. METHODS: Forty‐six depressed elderly subjects participated in the study. NBT (Pennsylvania's Penn Computerized Neurocognitive Battery [Penn CNP]) assessing attention, episodic memory, working memory, social cognition, complex cognition, and sensorimotor speed and ERP‐P300 (amplitude μV and latency ms) was recorded using an auditory oddball paradigm. RESULTS: Correlation test was run and Pearson’s analysis and revealed that there was a negative statistically significant linear correlation between working memory on NBT and P300 wave amplitude on ERP‐P300 (r = −0.34, P = 0.021) and between complex cognition on NBT and P300 wave latency on ERP‐P300 (r = −0.47, P < 0.001). No correlation was found between other tests on NBT and ERP‐P300 wave characteristics. Further, the regression analysis (R (2)) revealed that P300 amplitude was found to significantly predict the working memory (R (2) = 0.116) and P300 latency was found to significantly predict the complex cognition (R (2) = 0.224). CONCLUSION: Therefore, we conclude that neurophysiological measurements cannot be substituted by neuropsychological tests or vice versa; rather, higher brain functions should be estimated by both of the methods.