PAX-D is a major trial for Treatment Resistant Depression (TRD) by the National Institute for Health Research’s (NIHR). The Trial is being led from Oxford with patients also being recruited from other sites across the country. Cumbria, Northumberland, Tyne and Wear NHS Foundation Trust is the second site after Oxford to open to recruitment.

Depression is a common disorder usually treated in primary care with psychological therapies and antidepressant medication. However, a significant proportion of people (about 2-3 in 10) do not improve with current first-line therapies and are regarded as having TRD.

TRD is a major problem for both patients and society because of the high level of suffering and associated disability. Current medicines for TRD are not particularly effective for many people and often have adverse effects which patients find distressing.

There is some evidence that pramipexole, a medicine already commonly used in Parkinson's Disease, may be an effective treatment for TRD. PAX-D will compare the effects of pramipexole with placebo when added to current antidepressant medication for people with TRD. The trial will look at effectiveness in the short- term (after 12 week’s treatment) and in the longer-term (48 weeks). The trial will also assess the adverse effects of pramipexole and explore patients’ experiences of taking it.

Pramipexole is unlike current antidepressant drugs in that it acts on a brain chemical called dopamine, which is known to influence people’s motivation to pursue goals and affect how rewarding they find them. Lack of motivation is a key symptom of depression so any antidepressant effects of pramipexole may be linked to increased motivation. PAX-D participants will be asked to carry out a computer task designed to measure how pramipexole affects the dopamine system in the brain and how far this can explain its antidepressant effects.

If pramipexole is effective it could become a very useful treatment option for patients with TRD.

The aim of PAX-D is to determine whether pramipexole, added on to antidepressant treatment, is effective for patients with moderate or severe depression, who are currently depressed and have not responded to at least two antidepressants. We will examine this drug compared to placebo (dummy tablets) over 48 weeks.

Who can take part?

Participants need to be currently depressed and currently taking at least one antidepressant. If they are in secondary care, a discussion will take place with the participant’s care team to see if PAX-D is suitable within their treatment pathway. Suitable Primary Care patients can come in to the PAX-D trial via the CaPE (Care Pathway Enhancement) clinic once they have been made aware of the trial via a research register or their primary care team or via self-referral to

For more information please contact Principle Investigator Stuart Watson on 07772047430 or Research nurse/trial co-ordinator Nadia Burman on 07971030758.