"Pay and Conditions" may be a contributing factor not necessarily because of financial and emotional stress but because the available rewards affect the size and quality of the recruiting pool from which pilot trainees are selected.
There is also ample evidence, in terms of anecdotal divorce data, that the peripatetic lifestyle of travelling pilots for example, staying in a different hotel room each night, shift work, etc. does not necessarily make it easy to form strong family and social relationships of the sort that provide much support in times of stress.
To put that another way, if we treat piloting as "just another job", and make irrelevant comparisons with the employment stress levels of many posters here, we are missing the point.
Piloting isn't "an ordinary job" because there is a requirement for concise and accurate actions at all times in the air that cannot be delayed. In this piloting resembles the work of surgeons and trial lawyers and not much else. Pretty much everyone else can take time out to consider their course of action, pilots can't. Even ships Captains can anchor and train drivers can stop the train. Pilots can't.
I can well imagine a young pilot, perhaps with domestic personal issues, a crushing training loan to repay, a demanding job performance requirement, a demanding work schedule and an unsympathetic employer or captain, suddenly deciding their "dream job" isn't….and finding it is all too much to cope with.
Please spare me the outraged comments regarding professionalism and irrelevant asides, depression is a very real problem that attacks all levels of society and to think that pilots are some how immune is idiotic.
Mean while the knee jerk response of regulators will probably be to pull the medical certificates of anyone who has ever mentioned "the D word", consulted a psychiatrist or been prescribed SSRIs.
This will not be a popular subject with airline management.