I am not a physician nor do I have any formal medical training. However, I'm reasonably intelligent with decent observational skills. According to the Mayo Clinic, these are the signs of dementia:
Cognitive: mental decline, confusion in the evening hours, disorientation, inability to speak or understand language, making things up, mental confusion, or inability to recognize common things
Behavioral: irritability, personality changes, restlessness, lack of restraint, or wandering and getting lost
Mood: anxiety, loneliness, mood swings, or nervousness
Psychological: depression, hallucination, or paranoia
Muscular: inability to combine muscle movements or unsteady walking
Also common: memory loss, falling, jumbled speech, or sleep disorder
It all sounds like Trump, doesn't it? No wonder he won't release any personal information!