The speaker, Dr. Rohit Singh, says that there is no one behavior that can definitively identify someone who is suffering from depression, but there are some patterns that can be indicative. These patterns include changes in a person’s usual behavior, such as not being interactive, not going out to meet friends, or not attending school or college. Dr. Singh advises that if you notice these changes in a friend, you should reach out to them and see how they are doing. If they are not responsive, you can also check in with their parents. The important thing is to take action if you are concerned that a friend may be depressed.