Could an overactive immune system cause depression

Dr Neil Harrison’s work has received considerable media attention.  The BBC reported ‘Scientists in the UK are investigating whether some cases of depression could be triggered by an overactive immune system.
It’s a theory which is rapidly gaining ground – and there are now a number of trials testing whether some anti-inflammatory drugs might help some patients with depression.
Anti-depressants don’t work in a third of patients so if this new approach works it may offer them hope of an effective treatment.’