 Acute treatment will be administered daily, 5 days per week initially for three weeks i.e. 15 treatments. Following 3 weeks of treatment response will be assessed and the blind broken. At this point non responders i.e. HAM-D score 10 who have been receiving active treatment will be offered an additional 3 weeks of treatment at the same treatment parameters. Responders who have been receiving active treatment will enter the maintenance phase. At week 6 treatment response will again be assessed and non responders will be offered a final 3 weeks of active treatment while responders will enter the maintenance phase. At week 9 response will again be assessed and non responders will cease their participation in the trial, while responders will continue onto the maintenance phase. With regard to the sham treatment arm, subjects who respond to treatment and received sham treatment will be discontinued from the study at week 3. Those subjects who are classified as non responders and were in the sham treatment arm will be randomised to one of the two active treatment arms and receive an additional 3 weeks of active treatment. 