Country singer, Glenn Campbell has Alzheimer’s Disease. Alzheimer’s Disease is the most common form of dementia. It is a brain disease that causes problems with behavior, memory and thinking. Campbell, who’s 75 years old had and been suffering from short-term memory loss over the last couple of years, had been diagnosed with Alzheimer’s six months ago. The country singer who also dabbled into acting and hosting is scheduled to hold a series of farewell concerts this fall. His family decided to come clean about his Alzheimer’s so fans would have a better understanding of his condition.