[EEG findings in 40-60 year old subjects]

Electroencephalographic standard examinations were performed in 170 selected healthy persons aged between 40 and 60 years (average age 49 years). "Ideal Normal Traces" with a regular background Alpha-Activity were registered with only 39 test persons (22.9%). They showed an average frequency of 9.9 c/s and extreme values of 8.6--11.2 c/s. In 35 persons (20.5%) the only outstanding feature was merely a marked discontinuity and a considerable frequency lability of background activity, mostly combined with low voltage and a noticeable beta-waves component. In 17 persons (10%) a diffused increase of the Theta activity was found; the average age of this group was slightly higher (52.9 years) than in the remaining groups. Strongly marked paroxysmal-dysrythmic sequences were noted in 21 Test Persons (12.4%); these were in none of the cases clear sharp waves. In 58 Persons (34.2%) the essentiel changes were observed in the temporal regions being of a slighter nature in 46 persons (27.1%), and in 12 persons (7.1%) of a stronger character, lefthand significantly more frequent than righthand.