What Causes Dizziness And Memory Loss?

My brother is having spells. He has these events where he doesn t remember his family, even his young son. Sometimes he thinks he is back in a time or in another place. He takes off because he can t remember where he is. I ve googled the symptoms. He had an MRI and the report said there were unexplained shadow or spots on his brain. They haven t gone any further because they are saying they don t know what is wrong with him and don t have the expertise. I ve already lost one brother to some mysterious brain disease. Please help