Correlations between neuropsychological test results and P300 latency during silent-count and button-press tasks in post-traumatic brain injury patients

Neuropsychological correlates of the P300 in patients with Alzheimer's disease

OBJECTIVES

The P300 is a useful psychophysiological index that reflects cognitive functions; however, the relationship between P300 indices and neuropsychological tests in Alzheimer's disease (AD) patients is unclear.

METHODS

Thirty-one AD patients and 31 elderly normal control (NC) subjects were recruited. Age and education level were matched between the two groups. The relationship between the P300 and the Korean version of the Consortium to Establish a Registry for Alzheimer's disease (CERAD-K) assessment packet (including 11 neuropsychological tests) was examined in AD patients.

RESULTS

Compared to the NC subjects, the AD patients exhibited significantly decreased P300 amplitudes; however, there was no significant difference between the two groups in terms of P300 latency. After a permutation-based correction for multiple tests, P300 amplitudes at the Cz and Pz electrodes were significantly correlated with performance on the word list recognition, constructional praxis, and word fluency neuropsychological tests in the AD patients. Additionally, P300 latencies at the Pz and C6 electrodes were also significantly correlated with performance on the Mini-Mental State Examination, CERAD-K version (MMSE-K), and Trail Making Test part A (TMT-A) neuropsychological tests in the AD patients.

CONCLUSIONS

The results suggest that the P300 is responsive to the deterioration of language, memory, and executive functions observed in AD patients. Although there was no significant difference between the AD patients and NC subjects in the P300 latency, P300 latency has been shown to reflect impaired global cognition and attention deficits associated with AD. Our results suggest that P300 indices could be used as biological markers that indicate impaired neuropsychological functions in AD patients.

Correlations between event-related potentials with pictures recognition and WMS-RC scores in patients with memory disorder caused by severe traumatic brain injury

This study explored the possibility of using event-related potentials (ERP) for the measurement of picture-recognition memory and examined its correlation with the Chinese Wechsler Memory Scale-revised (WMS-RC) in patients with memory disorder caused by severe traumatic brain injury (sTBI). The subjects included 20 sTBI patients with memory disorder and 22 healthy individuals. Memory function was measured by using WMS-RC. Behavioral and ERP responses were recorded on-line during performance on a battery of picture recognition and the responses were analyzed off-line for recognition memory effects. Mean memory quotient (MQ) of patients with sTBI was significantly lower than that of the control group. Mean reaction time (RT) was significantly longer and the mean correctness rate (CR) of picture recognition was significantly lower in sTBI group than that of the controls. In controls, the main components of average ERP of picture recognition includes two positive-going waves, designated as P(170) and P(500), that appear 170 ms and 500 ms after stimulation when the subject could later successfully recall and recognize the pictures. P(500) amplitude of target stimulus was significantly higher than that of non-target stimulus. Compared to controls, P(500) responses of sTBI group were significantly delayed in latency (P<0.001) and lower in amplitude (P<0.001). P(500) latency showed significant negative correlation with MQ and the scores of "addition", "visual recognition", "picture recall", "visual reproduction" and "tactile memory" in WMS-RC. ERP of picture recognition provides a neurophysiological approach to directly assess memory impairment, and P(500) may serve as a helpful index for memory disorder caused by sTBI in forensic practice.