Complex sentence: By this stage of his life he had become increasingly reclusive, suffering from diabetes and heart trouble; a year before his death in Tasmania on 27 April 1995 (aged 78), he was diagnosed as having Alzheimer's disease.
Split into simpler sentences: By this stage of his life he had become increasingly reclusive, suffering from diabetes and heart trouble. A year before his death in Tasmania on 27 April 1995 (aged 78), he was diagnosed as having Alzheimer's disease.