Age Differences of Quantitative Electroencephalography and Current Source Density

Sung, Kyong Ae; Lee, Seung Hwan; Kim, Sang Rae

Abstract

OBJECTIVES
Age-related differences of the brain have been obtained by various methods. This study was aimed to explore the changes of quantitative electroencephalography (qEEG) and their source localization in normal aging.
METHODS
Thirty-seven healthy young adults (mean age 35.22+/-13.62 years) and thirty-nine cognitively-healthy elderly subjects (mean age 72.95+/-5.73 years) participated in the study. Resting-state EEGs were recorded while subjects were in a relaxed state. Relative qEEG powers of five frequency bands were analyzed for eye closed conditions: delta (1-3 Hz), theta (4-7 Hz), alpha (8-12 Hz), beta (13-25 Hz), and gamma (30-50 Hz). The standardized low resolution electromagnetic tomography (sLORETA) was used to identify the current source densities of each frequency band.
RESULTS
The elderly group showed an increase of beta and gamma power while the reduction of delta, theta, and alpha power compared with the young group. Controlling education as a covariate, the beta power was positively correlated with age, while theta power was negatively correlated with age in all subjects. sLORETA revealed that elderly subjects had reduced current source density at the cingulate gyrus in the theta band, while increased current source densities at the frontal, parietal, insula, and limbic areas in the beta band compared with young adults.
CONCLUSION
Our results suggested that qEEG could reflect normal aging. Cognitively healthy elderly subjects showed an increase of high-frequency power, while showing a reduction of low-frequency power. These functional implications were discussed.