Hemingway’s bizarre behavior in his latter years (he rehearsed his death by gunshot in front of dinner guests, for example) has been blamed on iron deficiency, bipolar disorder, attention-seeking and any number of other problems. After researching the writer’s letters, books and hospital visits, Farah is convinced that Hemingway had dementia — made worse by alcoholism and other maladies, but dominated by CTE, the improper treatment of which likely hastened his death.