THE DEGREE OF ALPHA ASYMMETRY AND ITS RELATION TO HANDEDNESS IN NEUROPSYCHIATRIC REFERRALS

While alpha rhythm asymmetry among normals is thoroughly documented, the significance of this finding in patients is not well known. The occurrences of alpha amplitude asymmetry in 82 clinical referrals of neuropsychiatric patients was studied in this research. Two separate means of quantifying the alpha asymmetry were used: The first by visual inspection; and the second by measurement in a standard manner. A handedness questionaire was administered and indicated that 77 of the sample were right- and five were left-handed patients. By measurement, the mean overall differences in the alpha amplitude between the hemisphere was small (4 per cent) and non-significant. Seventeen patients showed a difference of 15 per cent or greater, and in two the difference reached 33 per cent. It was concluded that alpha asymmetry must be interpreted with care because it was found that there was an association between left-temporal abnormalities and ipsilateral alpha enhancement, and the greater degrees of asymmetry were found in normal EEGs.