*sigh*
Yes, clinical depression is a mental illness.
There are a number of classifactions of symptoms which are considered mental illness, the models vary between countries, eg. in Europe Personality Disorders have traditionally not been viewed in the same classification or as treatable.
However 'mental illness' is a model, part of the organic medical disease model, a model which is gradually being broken down by a more holistic approach to overall health.
Whether or not symptoms ( such as mood swings or hormonal imbalance ) are classified as illness depends on their pattern and severity.
The best model is one where overall physical emotional and mental wellbeing are taken into account and best practice is the minimum of medication or intervention to acheive or maintain that.
Mental illness is not only a bad thing, like many of the difficulties in life it also imparts empathy, creativity and strength.
I certainly see myself as LIVING with bipolar rather than suffering with it, and I appreciate fully the many gifts having it has brought to my life.
The mental illness and violence connection is not born out in qualitative or quantative studies overall, in fact people with mental illness are many times more likely to be victims of violence than perpetrators in situations where it renders them vulnerable.
The only connection between mental illness and morality is the same as any other factor- people do not deserve or receive it as a punishment as was thought in less enlightened times, nor is it any more an excuse for bad behaviour. People with mental illness can and on the whole do take responsibility for managing it and minimising its impact upon others.
Mitigating factors in any criminal case do not over-ride morality or the legality of behaviours.
Post-partum depression can sometimes result in psychosis but it is yet another 'interesting' diagnosis seized upon by the media and alluded to in a small number of high-profile cases when the reality is that most people who suffer with it get through it without being a threat to society or to their child.
The people who are the biggest threats to others are those with strong entitlement, accepting and desensitised ideas about violence, and lack of empathy. Whilst some of these may also have mental illness, and indeed personality disordered people often have more than one diagnosis especially depression or compulsive traits, the high number of people across societies over time who have mental illnesses and do not act violently suggests that is the norm, not the handful of publicised cases which come to mind when a specific illness or circumstance is mentioned.
Even with NPD as many of us know here- we might have had a bad time but we weren't married to Ted Bundy etc.
If we're going to generalise, let's at least generalise to the norm!
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Enough said, I'm not upset with anyone, just on a bit of a mission with the whole subject, for which I apologise