Event-related potential and neuropsychological function in depressed older adults with cognitive impairment:...

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).

This study examines the relationship between conventional neuropsychological tests assessing various cognitive domains and an ERP-P300 in depressed older adults.

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.

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).

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.