Complex sentence: Mesrop II, the Armenian Patriarch of Constantinople was diagnosed with Alzheimer's disease in July, 2008, and was incapable of running the Patriarchate since then what led the Armenian community to a painful condition of uncertainty.
Split into simpler sentences: Mesrop II, the Armenian Patriarch of Constantinople was diagnosed with Alzheimer's disease in July, 2008, and was incapable of running the Patriarchate since then. This led the Armenian community to a painful condition of uncertainty.