Electroencephalographic photosensitivity among Zimbabwean youths

To clarify the factors associated with electroencephalographic (EEG) photosensitivity, the records of patients who had EEG examinations in the city of Harare, Zimbabwe between 1968 and 1996 were studied. EEG photosensitivity was confirmed in 107 of a total of 9082 youths (aged 0-25 years), giving an overall photosensitivity prevalence of 1.17% in the study population. Photosensitivity occurred more frequently in females than in males, and the peak age period for its occurrence was during adolescence. A significantly higher prevalence of photosensitivity was recorded among Whites and Asians than among Blacks, while the Coloured population had an intermediate prevalence. The monthly and seasonal incidence of photosensitivity in the present study showed no correlation with the prevailing mean monthly or seasonal temperatures, sunshine duration and sunlight intensity in Harare during the period covered by the study. These findings indicate that sunshine-related factors do not play a dominant role in the occurrence of photosensitivity, thereby negating previous opinions which attributed the relative rarity of photosensitivity in black Africans to high levels of exposure to sunshine in tropical Africa. Our findings therefore corroborate the view that photosensitivity depends primarily on genetic rather than environmental factors.