The Guardian gave enthusiastic coverage to news that Bristol University scientists were preparing to trial a new depression treatment, deep brain stimulation (When we turn the current on, the patients report the emptiness suddenly disappears, March 31). People with chronic depression would have electrodes pushed deep into the brain, and a small-scale trial suggested that the method might have some merit.

Mind welcomes all new research into treatments, but the track record of applying electricity to people's brains in order to counter depression isn't good. Our research into electroconvulsive therapy showed that 84% of patients experienced side-effects, which can include both the loss of memory and of learned skills. Half said they would not agree to have it again. It may be years before any side-effects of deep brain stimulation come to light.

Regrettably, miracle cures invariably aren't. Only a few years ago, a new type of antidepressant was being touted as a cure to depression. In time, though, we've seen that not only have these pills failed to solve the nation's mental health problems, but that they can also have serious and debilitating side-effects.

And this isn't just a health sector issue, it is a public policy priority. Forty per cent of incapacity benefit claimants have mental health problems; depression alone costs the economy over £10bn a year. The World Health Organisation predicts that depression will be the second biggest health problem globally by 2020.

We will best tackle this country's impending mental health crisis when we get to grips with some of its external causes. Chronic depression is connected with social, economic and personal factors such as unemployment, social exclusion, breakdown of relationships, or stress in the workplace.

The NHS is already struggling to meet demand for cognitive behavioural therapy, recommended as a first-line treatment, and for which there is already a strong evidence base: waiting lists top 18 months in some areas. The government economic adviser, Lord Layard, recently estimated that an extra 10,000 therapists are needed to meet the demand. Too often antidepressants are prescribed by doctors who lack the power or resources to address their patients' underlying issues.

"If the trials are successful," your report claims, "deep brain stimulation could be extended to the estimated 50,000 people in the UK who suffer from depression but cannot be helped by drugs or electroconvulsive therapy." If the NHS cannot currently fund comparatively cheap treatments such as therapy, how are we to expect that 50,000 people will be able to benefit from an expensive, invasive operation?

And who's to say that deep brain stimulation is the solution for these people? A narrow medical model of depression, a complex problem, fails to do justice to human psychology and the human condition. We hope that this research leads to positive results, but we also hope no one will ever suggest that using "hair-thin electrodes" to apply electricity "into the core of the brain" will be a substitute for a cohesive and holistic approach to mental wellbeing.

· Sophie Corlett is the acting chief executive of Mind, the mental health charity policyenquiries@mind.org.uk

· If you wish to respond, at greater length than in a letter, to an article in which you have featured either directly or indirectly, email response@theguardian.com or write to Response, The Guardian, 119 Farringdon Road, London EC1R 3ER. We cannot guarantee to publish all responses, and we reserve the right to edit pieces for both length and content