Relationship between phase lag index measured by electroencephalography and cognitive dysfunction in patients with cerebral small vessel disease.

OBJECTIVES

Cerebral small vessel disease (CSVD) is a primary cause of cognitive impairment (CI) in the elderly. This study aims to explore the relationship between the phase lag index (PLI), derived from electroencephalography (EEG), and cognitive dysfunction in patients with CSVD.

METHODS

This retrospective study included patients diagnosed with CSVD from May 2020 to December 2023. EEG data were recorded using 64 electrodes and analyzed for PLI across four frequency bands. Cognitive function was assessed using the Mini-Mental State Examination (MMSE) and the Montreal Cognitive Assessment (MoCA). Blood pressure variability was monitored using a 24-hour portable device.

RESULTS

The study included 264 patients, categorized into two groups: CI group (n = 102) and no CI group (n = 162). The CI group exhibited significantly lower global alpha-band PLI (0.28 vs. 0.31, P = 0.006) and reduced alpha-PLI across multiple electrode pairs (0.27 vs. 0.30, P = 0.004). Cognitive scores were also lower in the CI group (MMSE: 26.25 vs. 27.76, P = 0.004; MoCA: 25.38 vs. 26.63, P = 0.007). Additionally, the CI group had higher 24-hour mean systolic blood pressure (SBP, 140.68 vs. 136.36 mmHg, P = 0.038) and lower daytime SBP coefficient of variation (9.46% vs. 10.63%, P = 0.002). Receiver operating characteristic analysis revealed that F8-P8 PLI had an area under the curve of 0.608, indicating moderate discriminatory ability for identifying cognitive dysfunction.

CONCLUSION

Decreased phase synchronization in the EEG alpha-band correlated with cognitive dysfunction in CSVD patients, indicating that impaired neural connectivity may serve as a potential electrophysiological biomarker.