This is a randomized, assessor-blind, placebo controlled study in major depressive disorder (MDD) patients. Subjects receiving antidepressant drug (FLX) would be assigned to receive either 18 sham / active DCEAS for in 6 weeks. Changes in the severity of depressive symptoms over time are measured using depression rating scales. Brain glucose metabolic levels are measured using PET at baseline and endpoint. The most intriguing and expected result might be that acupuncture treated-patients may display comparable or even better outcomes and the clinical improvements by acupuncture are correlated with the restoration of the activities in the related brain regions.

Although the development of various classes of antidepressant drugs, represented by selective serotonin reuptake inhibitors (SSRI), has considerably improved the prognosis and the tolerability in the treatment of depressive disorders, the currently available antidepressant therapy is still incomplete, because there are about 40% of depressed individuals who cannot obtain full response and a large proportion of the patients experience recurrent episodes.

Recently the principal investigator has completed a clinical trial to test whether dense cranial electroacupuncture stimulation (DCEAS) could enhance the antidepressant efficacy in the early phase of SSRI treatment (fluoxetine, FLX) of major depressive disorder (MDD). It was found that DCEAS is clinically safe and effective in augmenting the antidepressant efficacy in early SSRI treatment. As we hypothesize that this normalizing effect is associated with the modulation of various nervous functions associated with the pathophysiology of MDD, we design this neuroimaging (PET) DCEAS study to delineate the related mechanisms.

The objective of this study are:

1) To compare clinical improvements on depressive symptoms between DCEAS and FLX monotherapy in MDD subjects; (2) To determine the effects of DCEAS treatment on glucose metabolic levels in related brain regions in comparison with healthy controls and FLX-treated patients, using PET scanning; and (3) To correlate between clinical improvements and changes in PET-measured activities of related brain regions in a pool of the subjects treated with DCEAS and FLX.

In this 6-week, assessor-blind, randomized, controlled study of DCEAS as additional treatment with the antidepressant drug FLX, a total of 82 patients with major depressive disorder (MDD) will be recruited. The patients will be randomly assigned to FLX (10-30 mg/day) combined with sham (n =41) or FLX with active DCEAS (n =41) (18 sessions, 3 sessions a week). Changes in the severity of depressive symptoms over time are measured using depressive instruments. Clinical response and remission rates are also calculated. Two sessions of PET scan will be conducted at baseline and endpoint. The study will be conducted at HKU School of Chinese Medicine, Queen Mary Hospital, and Kowloon Hospital, Hong Kong.

Inclusion Criteria:

1. with righthandedness;
2. have first-episode MDD diagnosed as the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV); and
3. HAMD-17 score is ≥ 20; and
4. never had any psychoactive medications.

Exclusion Criteria:

1. unstable medical conditions;
2. have suicidal ideas or attempts or aggressive behavior;
3. previously experienced manic, hypomanic, or mixed episode;
4. immediate family members have bipolar or psychotic disorders;
5. treatment with investigational drugs in past 6 months;
6. alcoholism or drug abuse in past 1 year; or
7. have needle phobia.