In a study published in the Journal of Affective Disorders, researchers at the Alpert Medical School of Brown University in Providence, Rhode Island, found no difference in outcomes between older and younger adults undergoing transcranial magnetic stimulation (TMS) for treatment-resistant depression (TRD).1
In older adults, approximately one-third of depressed individuals have TRD, and the burden of cognitive, physical, and functional impairment tends to be greater compared with younger individuals with depression.2,3 While randomized trials and other studies have demonstrated the efficacy and safety of repetitive TMS for TRD in the general adult population, outcomes in adults age ≥60 are unclear.4,5 Although some evidence suggests that TMS may be less effective in these patients, other findings indicate this may be because earlier trials did not include older adults or used a lower stimulation intensity (90% to 110% of motor threshold [MT]) than the current standard clinical “dose” (120% MT).
Proposed mechanisms for an age-related effect in TMS treatment include “atrophy of cortical gray matter (with associated greater coil-to-cortex distance), reduced synaptic connectivity, declining axon conduction velocities, and aging-related changes in lateralization, myelination, cerebrovascular function, and immune-inflammatory control,” according to the new paper. “Each of these factors could presumably alter the electromagnetic and anatomic properties of cortical tissue underneath the TMS coil, thereby altering the effect of TMS induced currents,” although few studies have investigated these possibilities, wrote the study investigators.
They performed a retrospective analysis of data from medical records to compare the TMS treatment response of patients with TRD age ≥60 (n=75) and age <60 (n=156). They expected to find a similar response in both groups, each of which received TMS at 120% for approximately 30 to 50 sessions on an outpatient basis. Change in the Inventory of Depressive Symptomatology–Self Report (IDS-SR) score from baseline to end point was the primary study outcome. Secondary outcomes included response and remission rates and change in Patient Health Questionnaire (PHQ-9) scores.
The results included the following observations:
- There was a significant decrease in both age groups on IDS-SR scores (older: baseline M=45.0, standard deviation (SD), 10.8; post-treatment M=26.7; SD,14.7; t=11.5, P <.001; younger: baseline M=48.1; SD, 10.5; post-treatment M=28.3; SD, 15.9; t=16.4; P <.001).
- There was a significant decrease in both groups on PHQ-9 scores (older: baseline M=17.4; SD, 5.1; posttreatment M=8.7; SD, 6.7; t=11.5; P <.001; younger: baseline M=19.3; SD, 6.0; post-treatment M =9.9; SD,7.1; t=15.3; P <.001).
- Neither group was more or less likely than the other to meet the criteria for remission (IDS-SR: 26.7% among older vs 25.0% among younger patients, χ2 (1) =.07; P =.78; PHQ-9: 33.3% in older patients vs 25.6% in younger patients, χ2 (1)=1.2; P =.25).
- Neither group was more or less likely than the other to meet the criteria for response (IDS-SR: 45.3% vs 44.9%, χ2 (1)=.004; P =.94; PHQ-9: 58.7% vs 55.4%; χ2 (1)=.47; P =.49)
Taken together these findings “demonstrate that age alone should not be considered a contraindication or poor prognostic indicator to TMS therapy,” the investigators stated.
- Conelea CA, Philip NS, Yip AG, et al. Transcranial magnetic stimulation for treatment-resistant depression: Naturalistic treatment outcomes for younger versus older patients. J Affect Disord. 2017; doi:10.1016/j.jad.2017.03.063
- Knöchel C Alves G Friedrichs B, et al. Treatment-resistant late-life depression: challenges and perspectives. Curr Neuropharmacol. 2015;13(5):577-591. doi:10.2174/1570159X1305151013200032
- Mulsant BH, Pollock BG. Treatment-resistant depression in late life. J Geriatr Psychiatry Neurol. 1998;11(4):186-193. doi:10.1177/089198879901100404
- George MS, Lisanby SH, Avery D, et al. Daily left prefrontal transcranial magnetic stimulation therapy for major depressive disorder: a sham-controlled randomized trial. Arch Gen Psychiatry. 2010;67(5):507-516. doi:10.1001/archgenpsychiatry.2010.46.
- Levkovitz Y Isserles M, Padberg, F et al. Efficacy and safety of deep transcranial magnetic stimulation for major depression: a prospective multicenter randomized controlled trial. World Psychiatry. 2015;14(1):64-73. doi:10.1002/wps.20199