Depression Causing Body Dysmorphic Disorder (BDD) Whilst trying to think of non-chemical/hormonal causes of low self-esteem when reading Is low self-esteem, a brain chemical imbalance problem, rather than a personality defect, and can&#39;t be fixed by any amount of counselling/self-help?, I have been considering Body Dysmorphia Disorder (BDD).

Whilst it is a mental disorder in its own right, I have been thinking that BDD can cause depression due to the constant upset caused by the feelings concerning the body, but not the other way round; yet the UK mental health charity, Mind, states.


  No one knows exactly what causes BDD. However, recent research suggests that there are a number of different risk factors that could mean you are more likely to experience BDD, such as:
  
  
  abuse or bullying
  low self-esteem
  fear of being alone or isolated
  perfectionism or competing with others
  genetics
  depression or anxiety
  


I am asking here specifically about depression because for the other reasons in MINDs list such as perfectionism or bullying, anxiety could cause BDD in my thinking.

With risk not necessarily meaning cause, in order for the risk to be quantified, there needs to be indication from studies and past clients that depression led to BDD rather than the other way round, and yet I am not convinced of this.

What studies are available which indicate that depression can cause BDD rather than the other way round?
TLDR version: it appears depression-as-a-risk-factor-for-BDD hasn't actually been studied, so the quoted UK NGO claims might stem from a blurring of risk factors and comorbidity.



Let's start by recalling what risk factor actually means (it does not mean cause): 


  Risk factors are characteristics at the biological, psychological, family, community, or cultural level that precede and are associated with a higher likelihood of negative outcomes.


So support the quoted passage in your question, one would only have to show that depression (from whatever cause) can happen before BDD in some individuals. If someone is predisposed to "go off the deep end" because of their body, they could possibly do that for any other perceived insufficiency in themselves (like thinking they're not being smart enough). The criteria to BDD are extremely specific, only a preoccupation with physical appearance counts; if someone ruminates or obsesses or over their (perceived) lack of intelligence, that doesn't qualify for BDD. With this in mind, depression being a risk factor for BDD doesn't so improbable. 

Alas, I came up empty for an actual longitudinal study where depression got worse before BDD... but I did find one close enough:


  We found several significant longitudinal associations between BDD and the comorbid disorders we examined. The association was strongest for depression. Time-varying associations showed that improvement in BDD and major depression were closely linked in time, with significant associations in both directions: improvement in major depression predicted BDD remission, and improvement in BDD predicted major depression remission. This finding suggests that the same etiologic processes contribute to both BDD and major depression in some subjects. 


The reason they could only talk of improvements (and not deterioration) is that this study had a treatment-based time frame. So there's wasn't much in the way of naturalistic observation sans treatment. That would probably require a much longer time scale... and I'm not convinced someone could get funding for that... especially since it raises ethics questions like observing depression getting worse in some patients but not doing anything about it, just so BDD aggravation could be observed.

On the other hand, the common sense logic (that you had) that depression might usually come after BDD, turns out to be supported by this study (well, again based on remission):


  in our sample depression may be largely secondary to BDD for many subjects, as a substantial proportion remitted from major depression following BDD remission. Conversely, after remission of depression, BDD tended to improve but less markedly. Our findings additionally suggest that BDD is not simply a symptom of depression. If it were, BDD would be expected to remit around the time of depression remission and during subsequent months. 


Frankly, I suspect that the NGO page in question might have simply confused (or amalgamated) risk factors with comorbidity. I'm saying this because a 2015 research paper notes that very little is know about risk factors for BDD. According to that paper, the only things which have been investigated as risk factors for BDD being:


"perceived teasing about general appearance"
"emotional, physical, or sexual abuse or neglect resulting in poor
attachment and body shame"
"a genetic predisposition for a need for symmetry or order"
"being excessively self-conscious about appearance changes during adolescence"


So, my conclusion from all this: it sounds somewhat plausible that depression is a risk factor for BDD (based on the common etiology [in some people] hypothesis), although it doesn't seem to have been formally/directly investigated, and the reverse occurence of events (BDD first, then depression) sounds a bit more common/likely.