Complex sentence: Campana spent a serene youth in Marradi, but in 1900, at approximately fifteen years of age, he came to be diagnosed with the first nervous disturbances that did not, however, prevent him from completing the several cycles of Italian school.
Split into simpler sentences: Campana spent a serene youth in Marradi, but in 1900, at approximately fifteen years of age, he came to be diagnosed with the the symptoms of nervous disturbances. These did not, however, prevent him from completing the several stages of Italian school.