Mental or physical?

'If problems in living are due to some brain disorder, then this a physical illness, not a mental illness.'

This is a quote from a letter in today's 'Guardian'.  It's hard to disagree with.

Of course, there are some conditions where it's not clear whether there's a physical cause but most dementia has an obvious physical cause, indeed the discovery of physical signs on a brain scan are now often used to establish a diagnosis.  We know that some people with dementia object strongly to having to attend mental health clinics.  Of course, mental health should not be stigmatised but also people's deeply-held views  -  prejudices even  -  need to be acknowledged.

The statement above should give food for thought to those who unthinkingly categorise all dementia as mental illness.