What is mental instability?

Mentally unstable refers to when a person's mental abilities are not steady and consistent resulting in an inability to cope with life effectively. They have difficulty dealing with everyday life and make poor choices that end up causing them more difficulty. It can be marked by anxiety, excessive worrying, aggression, becoming upset easily, temper tantrums (especially in public when most people try to control their emotions), moodiness, extreme highs and lows, depression, delusions, substance abuse, etc.

It should be evaluated by a professional and can be treated.