Whole body hyperthermia (WBH) shows promise as an effective treatment for depression, a randomised double-blind,sham-controlled trial, published in JAMA Psychiatry, has concluded.

A total of 34 participants aged 18-65 with DSM-IV major depression were randomised to receive either a single session of WBH or a sham session. Depression severity was assessed at baseline and during the six-week follow-up period using the 17-item Hamilton Depression Rating Scale (HDRS).

Participants assigned to the active intervention were heated to a target core body temperature of 38.5° C using infrared lamps. The sham session mimicked all aspects of WBH except intense heat and nearly three quarters of those receiving sham treatment (71%) believed that they had received WBH.

Overall, 29 participants completed at least one post-intervention assessment and were included in a modified intention-to-treat analysis. Compared with the sham group, the active WBH group had significantly lower HDRS scores throughout the follow-up period:

• Week 1: -6.53 (95% CI: -9.90 to -3.16)

• Week 2: -6.35 (95% CI: -9.95 to -2.74)

• Week 4: -4.50 (95% CI: -8.17 to -0.84)

• Week 6: -4.27 (95% CI: -7.94 to -0.61)

Adverse events in both groups were mild. However, elderly patients and those with medical conditions were excluded from the study.

WBH increases heart rate and cardiac output with the potential risk of inducing myocardial ischaemia, heart failure or arrhythmias in susceptible patients.¹

The wide confidence intervals reflect the small sample size. NICE suggested that a treatment-placebo difference of 3 points on the HDRS can be used as a criterion of clinical significance;2 the lower limit of the 95% confidence interval exceeded this threshold only at the week 1 assessment. Further larger trials are needed to justify the claim that a single session of WBH provides sustained therapeutic benefit.

It is suggested that intense heat stimulates a thermosensory pathway which projects via the spinothalamic tracts and a relay in the brain stem reticular formation to the serotonergic raphe nuclei. There is evidence of reduced activity in this pathway in patients with major depressive disorder.³

Atypical depression is characterised by mood reactivity and comforting behaviours, in particular consumption of comfort food (chocolate, cake) and warming up behaviours such as having a hot bath.⁴ WBH might be particularly effective for patients with this subtype of depression.

If we were to offer our patients a choice of antidepressants, CBT, exercise or a sauna, I suspect many would choose the latter. However, I do not think NICE is likely to endorse WBH any time soon. In the meantime, there would appear to be no harm in chocolate and hot baths for those patients who find them beneficial.

Dr Phillip Bland

Janssen CW, Lowry CA, Mehl MR et al. Whole-body hyperthermia for the treatment of major depressive disorder. A randomized clinical trial. JAMA Psychiatry 2016;73:789-95