My father seems to have declining memory, as he often forgets to bring his octopus and identity card when he is going out. I associate his current conditions with the symptoms of dementia. This morning, he went alone to a Chinese restaurant nearby for breakfast. However, even at midday, he has not returned home. I was very anxious and kept calling his mobile phone but he did not answer. I'm worried he has lost his way home. What should we do?