One of the most common features on this site are posts about the health benefits of a vegetarian diet. In general, vegetarians are healthier than meat-eaters, though people who eat a Mediterranean or Paleo diet and minimize meat are about as healthy as vegetarians.
Truth be told, vegetarianism isn’t always associated with positive health outcomes. In fact, when it comes to mental health, vegetarianism may be more strongly correlated with mental disorders than meat-eating. According to Vegetarian diet and mental disorders: results from a representative community survey:
Results
Vegetarians displayed elevated prevalence rates for depressive disorders, anxiety disorders and somatoform disorders. Due to the matching procedure, the findings cannot be explained by socio-demographic characteristics of vegetarians (e.g. higher rates of females, predominant residency in urban areas, high proportion of singles). The analysis of the respective ages at adoption of a vegetarian diet and onset of a mental disorder showed that the adoption of the vegetarian diet tends to follow the onset of mental disorders.
Conclusions
In Western cultures vegetarian diet is associated with an elevated risk of mental disorders. However, there was no evidence for a causal role of vegetarian diet in the etiology of mental disorders.
None of this means that you are at a greater risk of developing a mental disorder if you are a vegetarian(the study showed that people became vegetarian after showing symptoms of a mental disorder). It shows just a correlation between mental disorders and vegetarianism. Further studies may find no such correlation.
But assuming this is true, why is it so? Vegetarians may just be more sensitive in general, and to animal suffering in particular. In this way, we are like artists. In some studies, creativity is also linked with mental disorders. If you remember my post, The Vegan Brain is Different After all!, it wasn’t that big of a surprise that the brains of vegetarians seem to be wired a little differently from the brains of meat-eaters. Although vegetarians may generally be more prone to mental disorders, vegetarians tend to have higher IQs, on average.
People who enjoy torturing or killing animals or other people are also very likely to have serious mental disorders, but of a completely different kind. It is depressing to even think about such people, and is obviously even more depressing for animal-loving vegetarians.
AcroTrekker 
A very interesting post! I can see that people prone to anxiety may be drawn to vegetarianism for health reasons. Anxious people tend to have more health worries than non anxious people, so it would make sense for them to seek out healthy diets. And if I’m remembering the research correctly, some anxiety disorders are also associated with higher levels of empathy, which would explain why anxious individuals are more concerned about the wellbeing of animals. Now I’m going to check out your post the vegan brain. 🙂
Exactly. That’s another good reason vegetarianism likely correlates with mental disorder and especially anxiety.
I’m not sure if its related but I was a pescetarian for about a year and a half and suddenly started having panic attacks which was followed by depression about two months later. I had doubts about my diet, I wondered if I was deficient in certain vitamins that might have been causing my problems. But it wasn’t the only cause I was considering. During the worst of my depression I ended up relapsing back to eating chicken, beef and pork, not as an experiment to see if I felt better but as a way to feel better emotionally – I used food, was binging on McDonalds haha. Anyways, about this same time I was beginning to get on antidepressants. Maybe two months later, once the medication had fully kicked in and I had been eating meat for a while, I began to feel better. I can’t tell if its the meat or the medication but I feel great now. Trying not to let myself think I can’t live without meats, I have been struggling with the idea for the past four months. A week ago I decided i’m going to go vegetarian, removing fish from my diet also, unlike last time. I am happy to return to this lifestyle however I do still have doubts and anxiety that I might relapse back into depression or panic attacks might return.
So like that report that came out about vegetarianism and depression, I have no idea if they are related, but I consider it due to my experience (which I am still confused and maybe even in denial about haha).