Abstract
Deep brain stimulation (DBS) reduces depressive symptom scores in many patients with treatment-resistant depression (TRD). However, it is unclear whether the observed improvement is similar across various symptom dimensions (e.g., anhedonia, anxiety, insomnia) or if some require additional clinical attention. Using a retrospective chart review, we assessed the trajectory of HAM-D-17 and MADRS scores during vALIC or slMFB DBS treatment within different symptom dimensions (HAM-D-17: 1) affective/anhedonia, 2) somatic/anxiety, 3) insomnia; MADRS: 1) affective/anhedonia, 2) anxiety/vegetative, 3) hopelessness) after at least a 25 % symptom reduction (partial response) at any time during their treatment course (n = 34 for HAM-D-17, n = 25 for MADRS). Results showed that each of the assessed symptom dimensions was significantly reduced compared to baseline at each of the assessed time periods (last follow-up: 2-15 years) after (partial) DBS response onset, which occurred at a median of approximately 2.5 months. Additionally, there was a significant interaction effect between symptom dimension and time period (HAM-D-17: F (12,1655.46) = 5.46, p < 0.001; MADRS: F (12,938.73) = 2.40, p < 0.01). Model coefficients indicated that insomnia symptoms (HAM-D-17) and anxiety/vegetative symptoms (MADRS) improved at a slower rate than the other symptom dimensions. Additionally, higher baseline scores in the HAM-D-17 somatic/anxiety dimension were significantly associated with a larger percentage reduction in overall symptoms after DBS (n = 39, F (1,32) = 12.371, p < 0.01). Our findings demonstrate that DBS for TRD effectively treats depressive symptoms in all dimensions, although insomnia symptoms may improve at a slower rate, and that patients with more anxiety symptoms, who typically tend to have worse pharmacological treatment outcomes, may particularly benefit from DBS.