Matthew is 44 years old and attends the GP surgery following his marital breakdown. His wife states he is aggressive and that his personality is no longer the same. On further questioning he admits he is irritable and is upset this has impacted his marriage. His mood is low although he denies any thoughts of suicide or self-harm. His father left his mother when he was a teenager, but he recalls that he sometimes had ‘funny movements’ and problems with walking and was told he passed away in his early forties.
What is the most likely diagnosis?