Not saying this is for everyone, but I started taking antidepressants to help with my mood instability. I never really had shutdowns, but I had rage outbursts due to mood instability. I'd suddenly become all overaware of myself and feel a monster growl inside me and might erupt at any given moment, if someone said the wrong thing to me or something. This only occurred around close loved ones. I'd suddenly become fed up easily of smiling and being chilled, and instead go all sulky and snappy and it would sometimes escalate into an outburst involving me shouting, swearing, crying and slamming doors. For the sake of my loved ones and their sanity I went on antidepressants and I haven't had an outburst since, and it's been like 9 years now. I still have emotions, you understand, and often quite intense, but it doesn't cause me to fly up at loved ones, so I feel more in control and appreciative of my surroundings. That's the difference.