Appendectomy supposedly increases risk of psychiatric illnesses

First a little background... How did I come up with checking for this? Well, there is a connection between mental maladies and the guy flora. People with various diagnoses have an altered gut flora. And here is a little chicken or the egg... Does gut flora aberrations cause psychological conditions or the other way around?

The next step was the supposed purpose of the appendix. Long thought to be a superfluous organ, later theories indicated it holds a backup of the gut bacteria. I.e. after illness the bacteria can be restored by the appendix.

So I then considered that if that is the case is there a connection with psychological illnesses? I did a search and a study indicates there is.

It does according to a study increase the risk of depressive disorder, bipolar and anxiety disorder. But according to the study only if people are subjected to procedure before age 14.

[link to pubmed.ncbi.nlm.nih.gov (secure)]

So should appendectomy only be performed if absolutely necessary? Are there even alternative treatments? In emergencies there's maybe no alternative.

What do you think about this?