The distress, disability and also expense, personally and societally, caused by such disorders, cannot be overemphasised. It is no overstatement to describe serious, recurrent depression as a living nightmare.
Stigma and misunderstanding also make it hard for sufferers of mental health problems to be open or to seek treatment for fear of repercussions.
Implicit in these is often the suggestion that sufferers are at fault or being weak, or even being devious and "manipulative".
High-profile cases of sportspeople, entertainers and politicians bring home the point that depression is no respecter of status or fame.
However it is tragically clear that many employers or public agencies still do not appreciate how serious such disorders are.
Yet the suggestion mental disorders such as depression are random afflictions like influenza is to misrepresent them and their causes in important ways. In fact depression represents a wide range of culturally-relative syndromes.
Although it is clear from research that we all vary in our genetic vulnerability to mental disorder it is equally well documented the principal causative factors in the still increasing rates of depression documented by the World Health Organisation are psychosocial and developmental.
Considerable research on this topic demonstrates clearly the damaging psychological effects of early life social adversity, emotional deprivation, family losses and stress in general,with subsequent long-lasting neurobiological effects on the developing nervous system.
These contribute to later vulnerability to depression in the face of later stressful life events. We all have a breaking point.
Children psychologically "internalise" and are formed by the values, beliefs and practices of the culture they live in.
This may result in adults with negative thoughts and self-critical "voices" and self-sabotaging or abusive coping patterns. These problems represent much of the work of any psychological treatment.
The general effect of social and community context on prevalence and outcome of mental disorder is also well documented. The effects of inequality appear to be mediated not simply by absolute material living standards, but rather something relating to a sense of meaningful collectivity, pride and common purpose for which inequality is only a proxy marker.
These problems are seen in demoralised communities of indigenous peoples. Parallels have been drawn between these and areas of post-industrial central Scotland. There is an important sense in which depression must also be conceived of as whole societal disorder. This highlights the dangers of unwittingly colluding with societal dysfunction if we focus purely on treating individuals and also the dangers of inappropriate "medicalisation" of human distress and suffering.
The answer to an epidemic of lifestyle related heart disease was not to train more cardiac surgeons. We must certainly ensure decent provision for individual sufferers, even limited in effectiveness as they are.
This provision still remains inadequate given mental health remains a Cinderella speciality.
An urgent challenge is to address preventive interventions towards the root causes of these problems. Some commendable initial progress has already been made in Scotland with recognition for example of these problems by the outgoing Chief Medical Officer Sir Harry Burns. To address this problem fully will depend on the willingness of our society to understand and act on these issues.
This is a matter of some urgency given the UK overall ranks currently as one of the most unequal and, on many measures socially dysfunctional countries in the developed world.
In the context of the independence referendum, it could be argued that only with a significantly greater degree of autonomy with regard to shaping the socio-economic structures and processes would we in Scotland be able to strive effectively towards significant improvements in our overall mental health and wellbeing.
We have a major task on our hands collectively in addressing the increasing incidence rates of a range of mental disorders.
But these are not amenable to any individually-oriented "quick fixes" however clinically convenient or politically expedient it may be to suggest this.
Dr Ian B Kerr is a consultant psychiatrist and psychotherapist based in Stirling