EEG mapping in middle aged normal volunteers: the impact of cerebrovascular risk factors.

The impact of major risk factors for stroke on EEG mapping and routine EEG findings was evaluated in volunteers with no clinical signs of cerebrovascular or other neuropsychiatric disease. Focal changes were seen in 22 subjects (30%) by means of EEG mapping, but in only 12 cases (16%) when routine-EEG was used (p < .05). 4/35 (11%) volunteers without RF had focal changes while this was seen in 18/39 (46%) subjects in whom risk factors (RF) were found (p < .01). An association was seen between the presence of EEG foci and number of RF. 59% of subjects with 2 or 3 RF had focal abnormalities as opposed to 36% of those with 1 RF and 11% of RF free individuals (p < .05). The findings could be confirmed by averaging the EEG data according to the different number of RF revealing statistically significant differences between each of the 3 groups. Using routine EEG alone no significant correlation to the presence or number of RF was found. Our data demonstrate EEG abnormalities in a considerable portion of normal middle aged individuals which in part may be attributed to the presence of RF.