Unilateral and bilateral repetitive transcranial magnetic stimulation for treatment-resistant late-life depression

The management of late-life depression is challenged by high rates of treatment-resistance and adverse effects, along with medical comorbidities and polypharmacy. Together with the limited data on managing treatment-resistant depression in older adults, there is a need for investigating the efficacy of nonpharmacological treatment strategies. Repetitive transcranial magnetic stimulation (rTMS) is one modality that may better serve this patient population.

The present study examines data from two previous clinical trials (NCT00305045 and NCT01515215) to explore the efficacy of bilateral and unilateral high-frequency left-sided (HFL) rTMS in older adults suffering from treatment-resistant depression. A total of 43 adults aged 60 or older with a current major depressive episode were randomized to bilateral sequential, unilateral HFL, or sham. Bilateral sequential stimulation involved low-frequency (1 Hz) right dorsolateral prefrontal cortex (DLPFC) stimulation followed immediately by high-frequency (10 Hz) left DLPFC. The unilateral condition was HFL stimulation alone, and the placebo condition was either HFL or sequential bilateral form of sham. The primary outcome was remission of depression.

Participants receiving bilateral rTMS experienced greater remission rates (40%) compared with unilateral (0%) or sham (0%) groups. Response to rTMS in the Hamilton Depression Rating Scale scores similarly favored the efficacy of bilateral rTMS.

This study suggests that sequential bilateral treatment may be an optimal form of rTMS when used for treatment-resistant depression in older adults. Further large-scale comparative effectiveness trials of bilateral rTMS in this population are warranted.