Introduction

Obsessive-Compulsive Disorder (OCD) is a mental illness that involves the experience of both obsessions (intrusive, unwanted thoughts or images) and compulsions (physical and/or mental actions done in response to obsessions in attempt to reduce distress) [1]. On average, about 1 in 40 adults, or around 8.2 million adults, in the United States will develop OCD in their lifetime [2]. Additionally, OCD has been found to be the fourth most common mental illness, globally impacting 2–3% of the world’s population [3].

This disabling condition leads many sufferers to experience a lower quality of life (QoL), with difficulty functioning in a variety of life domains including general, physical, psychological and social domains [4–8]. Specific factors that are associated with low QoL in those with OCD include psychiatric comorbidities, low perceived and actual social support, adverse effects of medication, effort expended engaged in severe obsessions and compulsions, social stigma, and strained relationships, especially in the context of accommodation (i.e., when others participate directly in or are involved in a person with OCD’s compulsions, rituals, and/or avoidance) [4,5,8].

First-line treatment for OCD includes Exposure and Response Prevention (ERP) therapy and medications that target serotonin receptors, primarily Selective Serotonin Reuptake Inhibitors (SSRIs) [9–11]. Additional standard treatment often includes adjunctive therapies such as Acceptance and Commitment Therapy (ACT), Dialectical Behavior Therapy (DBT), Cognitive Therapy (CT), Mindfulness-Based Therapy, and augmenting medications [11]. While a combination of these treatments has been shown to be effective in symptom reduction, 40–60% of patients do not respond fully to traditional treatments [12], and about 20% of patients continue to experience severe and persistent symptoms [13].

Deep brain stimulation (DBS) is a minimally invasive neurosurgical treatment option for sufferers with refractory OCD [13]. DBS has regulatory approval in the United States (Food and Drug Administration – FDA) for Parkinson’s disease, essential tremor and epilepsy [14–16]. DBS is approved via a Humanitarian Device Exemption (HDE) for OCD [17–19] and dystonia [20], and OCD is the only psychiatric indication with FDA-approval.

DBS requires brain surgery to implant electrodes in the deeper structures of the brain. This surgery is done using a method called stereotactic neurosurgery, in which the surgeon uses brain imaging and three-dimensional coordinates to guide insertion of the electrodes. The electrodes are connected to a pacemaker-like device in the chest wall that delivers electrical impulses. Stimulation modifies abnormal brain activity that occurs in OCD, with the goal of reducing obsessions and compulsions [21,22].

When DBS is used for OCD, about 60% of treatment-refractory patients experience a good response, defined as at least a 35% reduction in Yale-Brown Obsessive Compulsive scale (Y-BOCS) [13]. Across several meta and systemic analyses, the mean reduction in Y-BOCS scores across all patients who received DBS was 40% [23–30], which is clinically significant [13]. While many of these analyses had high levels of heterogeneity in design, population, and intervention timelines [31], there does appear to be an overall reduction of OCD symptoms in patients with treatment refractory OCD [30,32]. Additionally, DBS often leads to significant improvement in global functioning [21,23,24,27,30,32,33], a reduction in anxiety [28,32,33], and an improvement in cognitive performance [28].

Many of the various quantitative measures used to study QoL in DBS for OCD, include similar QoL domains and consistently demonstrate OCD symptom reduction, mood improvement, and improvements in areas of overall functioning post-DBS [8,25,26,32–36]. Conversely, the social/relationship domain often remains impaired in OCD [33,36]. Symptom reduction alone, as measured by quantitative rating scales, fails to capture the full impact of treatment; focusing on quality of life and functional outcomes is essential to understanding the broader patient experience [29]. A holistic approach, including both objective and subjective data, yields more comprehensive information about functioning beyond symptom reduction, including external influencing factors, actual opportunities in a patient’s life for achievement and functioning, and how the patient feels about their current life situation and functioning vs. societal expectations (e.g., sometimes patients are quite satisfied with a living situation and functioning level that society may deem inadequate or not appropriate). Focusing on QoL also may address common measurement distortions that arise from strictly quantitative data, such as the affective fallacy, which is the tendency for people to use their current and temporary affective state to make judgments about how satisfied they are with their lives in general [29] or hedonic adaptation, a psychological process where people adapt to new circumstances and return to the same baseline level of happiness [37].

Qualitative data fills in these gaps and allows us to better understand patients’ own perceptions of mental health and life changes. Qualitative data in the existing literature on DBS for OCD reflects similar improvements in OCD symptoms, mood, and anxiety [38–41] and maintenance of improvement when combined with ongoing therapy and support (e.g., exposure response prevention) [38,42]. Additionally, patients may experience improvement in perception, cognitive flexibility, and confidence [38,39,41]. Many patients also experience ongoing difficulties in certain areas. Specifically, factors that contribute to ongoing lower QoL include burden of normality (i.e., the difficulty individuals have transitioning from a state of illness or disability to a state of improved functioning or normalcy) [42], social difficulties, and adjusting to being symptom free [36,38,41,43].

Methods

Results

Summary evaluation of the percent change in Q-LES-Q-SF and Y-BOCS post onset of DBS therapy demonstrated that the majority of subjects evinced an improvement in quality of life and reduction in OCD severity (Fig 1). We sought to determine whether improvements in these two scales correlated at the individual subject level. Accounting for within-subject clustering and potential autocorrelation as a function of repeated measures, we applied an autoregressive corrected linear mixed model to association between change from baseline in Y-BOCS and Q-LES-Q-SF. The analysis confirmed a significant negative association between Y-BOCS severity and quality of life (β = −0.15, SE = 0.04, p < .001) with individual patient slopes that ranged from 0.106 to −0.87, indicating variability in the strength of the coupling between mood and OCD symptoms and substantial inter-individual heterogeneity in the underlying relationship. This suggests that while improvement in quality of life generally tracks with symptom reduction, the strength of this coupling is patient-specific (Figs 1 and 2). The rate of change in both the Q-LES-Q-SF and Y-BOCS were quite variable, and the patient-specific nature of this change can be further seen in Fig 3. In this OCD-DBS cohort, at final follow-up, the overall improvement in QoL was 43.48 ± 39.85% (measured as percent change from baseline).

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Fig 1. Time course of change in Y-BOCS and Q-LES-Q-SF across subjects: The range of duration for the follow-up period varied across subjects (maximum range: 974-3203 days post initial stimulation).

Individualized trajectories of percent change in Y-BOCS and Q-LES-Q-SF were represented over the available follow-up period. Individual dotted lines denote unique subjects. The two thick lines are the linear least square regression (loess) for each metric across all subjects. LOESS data are modeled up to 72 months follow-up across subjects.

https://doi.org/10.1371/journal.pone.0350293.g001

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Fig 2. Association of Y-BOCS and Q-LES-Q-SF change during DBS follow-up: Using a linear mixed model, we observed a significant association between quality of life and OCD severity, finding that for every 1-point increase in QOL (Q-LES-Q-SF), OCD symptoms (Y-BOCS) dropped by 0.15 points.

The negative relationship supports the conclusion that as Q-LES-Q-SF improves there is a concordant improvement in Y-BOCS.

https://doi.org/10.1371/journal.pone.0350293.g002

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Fig 3. A. Representative Subject (7) showing the change overtime for Y-BOCS and QoL at 1 month resolution.

It shows that the QoL is more variable than the YBOCS. B. All subjects – same resolution (each circle size represents the IQR (interquartile range) for all subjects at that time point. Each dot size conveys the number of subjects which will influence IQR). This is a higher resolution plot in 30-day medians.

https://doi.org/10.1371/journal.pone.0350293.g003

Analysis of the qualitative data from the Q-LES-Q-SF revealed several themes across participant outcomes. Many participants reported their pre-DBS experiences as “terrible,” “bad,” or “horrible,” noting that their OCD symptoms occupied considerable amounts of time and inhibited their motivation to engage in activities of daily living, relationships, work/school, and hobbies (Figs 4 and 5). This was reflected in baseline QoL scores, with nine of ten participants endorsing QoL being affected in at least one area due to OCD symptoms.

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Fig 4. Self-reported changes regarding quality-of-life domains post-DBS: In interviews, patients were asked about each domain in the Q-LES-Q-SF scale to understand whether quality of life stayed the same, improved, or worsened because of DBS surgery.

The figure depicts patients’ responses to the interview questions, including two new categories of “fluctuated” and “complicated,” to include patients who felt that their experience did not fall under “improved,” “stayed the same,” or “worsened.”.

https://doi.org/10.1371/journal.pone.0350293.g004

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Fig 5. Visualization of qualitative coding process for pre-DBS themes: Select patient quotes from interview transcripts were used to illustrate the qualitative coding process.

The figure does not include all pre-DBS themes or every patient quote associated with each theme.

https://doi.org/10.1371/journal.pone.0350293.g005

At the time of the interview, eight of ten participants reported that life improved following the DBS procedure (Figs 4 and 6). The most notable changes were mood improvements, improved overall functionality, increased functionality around household tasks, slightly increased productivity at school or work, more engagement in hobbies (due to increased interest and increased energy), and decreased time spent on obsessions and compulsions (Fig 4 and Table 1). Eight of ten participants noted a reduction in frequency and intensity of compulsions. One participant described, “Yeah, my OCD is really good right now. You know, the obsessions aren’t...I don’t think about them that much. They don’t come around as often.” Another noted that they were “not as constricted by OCD [anymore].” While participants frequently noted improvements in family and social relationships, they also expressed a desire for more social connection and ability to feel more comfortable in social settings. One participant noted, “That’s the part that still gets me a little bit…. I just wish I had a little bit better of a social support.” Other participants echoed this sentiment. Although participants felt better equipped to establish and maintain boundaries with others and prioritize their own needs following DBS, they also perceived these changes as contributing to smaller social circles and a diminished sense of overall social support. There were two individuals that reported improvements in their living situations (due to seeing more functionality following DBS). These participants namely noted improved functionality with ADLs in their living environments (Table 2).

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Table 1. Participant quotes indicating improvements in functioning.

https://doi.org/10.1371/journal.pone.0350293.t001

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Table 2. Participant quotes regarding housing and living environments.

https://doi.org/10.1371/journal.pone.0350293.t002

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Fig 6. Self-reported ratings of improvement and disappointment in quality-of-life post-DBS: The figure displays patient responses to the interview questions: “Where would you rank the level of improvement in the quality of your life since receiving DBS surgery on a scale of 0-10, where 0 is not improvement in quality of life and 10 is the tremendous improvement in quality of life?” and “Out of all the domains on the Q-LES-Q-SF, were there any that stayed the same? If yes, are you disappointed that things haven’t changed? Where would you rank that level of disappointment on a scale of 0-10, where 0 is not disappointed at all and 10 is the most disappointed you’ve ever felt?”.

https://doi.org/10.1371/journal.pone.0350293.g006

Other factors that improved QoL that participants shared are highlighted in the following quotes:

• “I think a big part was just having like so much contact with the team, honestly, and just like having that outside support because like, it can be so hard and isolating. It was also nice to get an outside perspective.”
• “Volunteering helped. It led to me getting a job. That and going to church helped with socializing.”
• “Being able to set boundaries and not engage with friends who don’t respect me.”
• “Advocacy work has been really satisfying; helping others and connecting them with resources.”

In addition to specific areas of change post-DBS, participants were asked about the timeframe of changes, as well as if changes felt long-lasting. 9 out 10 participants noted immediate improvement in their mood, stating that the improvement occurred the same day as the first programming session or within the first several weeks of programming. Eight out of 10 participants noted that their OCD symptoms improved with the first 3–6 months. Finally, 5 out of 10 participants reported long-lasting improvements from DBS, while 3 out of 10 participants noted partial long-lasting improvements, with partial symptom return and 2 out of 10 participants reported feeling no effect from DBS anymore. A summary of each subject’s responses for timeframe and longevity of DBS impact can be found in Table 3.

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Table 3. Summarized participant responses on timeframe and longevity of DBS impact.

https://doi.org/10.1371/journal.pone.0350293.t003

During the interviews, a trend emerged where the participants with higher reported symptoms and lower quality of life, were hesitant to share their experience about DBS. One participant stated, “I’m not sure you want me for this research. I’m not a very good example of DBS helping right now.” During the interview, the same participant also noted, “I know my current state is not a reflection of DBS. There are a lot of external factors that are impacting me and my life.” The rigidity and lack of insight into the bigger picture led 6 out of 10 of the participants to initially state that either their quality of life was poor or had not changed. However, by the end of each interview, participants each noted the improvements in their overall symptoms and lives. This can be seen in the following quotes from the same participant:

• “Ok, yes. DBS improved some areas [of my life]. My family relationships were definitely improved. I involved them more in my life which improved our relationships.”
• “I mean, after [DBS], I feel like I probably...did have a better outlook on life... Well not probably. I did have a better outlook on life.”

Other patients with similar initial reactions had comparable sentiments (Table 4).

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Table 4. Participant quotes regarding big picture improvement.

https://doi.org/10.1371/journal.pone.0350293.t004

Discussion

Our qualitative data provides a more robust picture of quality-of-life improvements than captured in quantitative measures alone. Specifically, patients note that DBS has given them a new baseline and expanded their belief in self-capability, as well as allowing them to consider life opportunities they hadn’t previously thought possible (e.g., school, relationships, or hobbies). Therefore, quantitative measures may seem to not improve as much because the range of life opportunities has expanded for our patients post-DBS, i.e., the scale has been reset.

Since DBS therapy for OCD does not address external stressors, these lived experiences highlight the importance of comprehensive post-treatment care. A narrow focus on DBS therapy alone will overlook key factors that influence long-term outcomes and QoL. These findings inform future recommendations for clinical care and support following DBS, and potentially even prior to DBS surgery, during the preparatory phase. While DBS can be an effective intervention to treat severe and refractory OCD, it should not be a stand-alone treatment.

In our research. following up with therapy (typically Exposure Response Prevention therapy) and appropriate medication management were crucial tools in managing symptoms during long-term follow up. Several participants reported that, while DBS helped to initially mitigate OCD symptoms, these effects diminished somewhat over time. In the quartile follow-up assessments, 4 participants noted the need for ongoing, additional individual therapy and medication management following DBS. One participant remarked, “[Since DBS, I’ve had] several changes to medications, primarily to combat refractory depression.” Another participant noted, “I believe the DBS was the tool, but ERP is how I changed old habits.” These reflections highlight the need for step-down care following DBS and the importance of reinforcing positive results from DBS through continued medication management and skills practice. However, while the importance of post-DBS ERP may be intuitive and shown in qualitative data, previous more controlled data did not unambiguously show this additional effect [48].

The participants who displayed lower levels of satisfaction post-DBS and had more difficulty sustaining improvement were often inconsistent with following recommendations for medication and therapy. They were more likely to hope that DBS alone would manage their symptoms. Participants who had more realistic and balanced expectations of the role of DBS post-surgery were more likely to be active and engaged in their life and treatment. These participants were better able to recognize the limitations of DBS and how DBS was not a be-all-end-all. These participants were more likely to be active in either therapy, medication management, holding an occupation or attending school, engaging in vocational training, engaging in social skills training, or actively improving their relationships.

External factors, such as psychiatric and physical co-morbidities, housing, social support, grief and loss, and family dynamics also impact mood, OCD symptoms, and functioning. While DBS cannot control external factors, it is necessary to recognize that external factors can still have a large impact on perceived QoL. It is important to assess a variety of areas pre and post DBS treatment, including symptoms, functioning domains, and insight [49]. When considering how responsive a patient is to DBS. Without considering these factors, a patient may be incorrectly deemed non-responsive to the treatment.

Several participants experienced fluctuations in mood during DBS therapy and attributed these changes to external factors, including symptom status of co-morbidities, physical health issues, financial status, and relationships, rather than related to DBS. The two participants that reported the least improvement in the qualitative interviews currently have active eating disorders. These results are consistent with previous research demonstrating the significant negative and long-lasting impact eating disorders have on quality of life and functioning [50–52]. Despite lower improvement scores and higher levels of disappointment with DBS, both patients did acknowledge that they would not want to change their decision to receive DBS and that DBS has improved at least one area of their lives. If our team was not doing thorough assessments and gathering qualitative data, these patients may have been deemed non-responsive to DBS.

Patients may retrospectively recognize that their mental state pre-surgery may have interfered with their ability to fully understand pre-surgery psychoeducation about expectations post-DBS [41,53–57]. Additionally, programming with patients who have low insight may lead to motivation, ability to recognize symptom changes, and may change long-term goals and expectations across individuals. In our research, this was evident during the qualitative interviews as discussed in the results section and Table 3.

In order to accurately acquire the most comprehensive picture of DBS responsiveness and current QoL, thorough assessment should be completed around level of insight prior to surgery and post-surgery. Expectations for DBS treatment, co-morbidities, and external factors (e.g., support system, financial status, occupational status, etc.) pre- and post-surgery should also be evaluated.

Additionally, the psychiatrist adjusting the DBS stimulation parameters should use objective clinical observations about patient improvements, as well as permit family and friends to participate in programming sessions to help with assessment and to allow patients to feel more comfortable [57]. Whether the patient has insight into their symptoms or not, having additional observations and data can give programmers and treating clinicians information to better address patient care. For instance, gathering information from family and friends may provide insight into accommodation levels and compliance with ERP homework and medication routines. It is also important to note that a patient’s assessment of their own progress may be impacted by how they feel transitioning to a life without symptoms and what their role in their life and relationships may be. This “burden of normalcy”, transition to a life post-OCD, and new identity (e.g., not being sick), as well as higher desire for socializing, but having a lack of social network or being out of practice, may also lead to the difficulties our subjects discussed in their qualitative interviews [36,38,43,56]. Potential treatment recommendations to address some of the ongoing issues may include occupational therapy, social skills training, and group therapy to address deficits experienced in executive functioning, relationships, and school/job functioning. Peer support groups for patients who have had DBS for OCD may also be a means for improving quality of life in the social domain [41,56].

Limitations of this study include the small sample size, absence of pre-DBS quantitative data for two who had DBS surgery at an outside hospital, and possible affective biases that may be displayed by patients. The interviews were conducted following surgery and programming, and participants were at different time points in their programming, ranging from 2 years to 8 years post-surgery. This may have led to skewed data due to memory biases and current life circumstances impacting how participants viewed the success of their treatment. Future research could include interviews and assessments completed both pre- and post-surgery. Family members and caregivers could also be interviewed to obtain more robust information about patients’ QoL and differences in experienced versus perceived QoL.

Conclusion

It should not be assumed, based on quantitative measures alone, that QoL has not improved or has only minimally improved in participants with OCD post-DBS. Due to increased awareness of life opportunities, participants’ subjective reports of improvement provide more accurate and useful perspectives. This is important because accurate perspective allows for more individualized and holistic interventions based on participants’ life satisfaction and personal goals. DBS alone is not sufficient for improving QoL, and post-DBS treatment should include support around interpersonal relationship and social skills, executive functioning, employment, and the transition to more independent living. Managing expectations prior to DBS surgery often leads to improved insight post-DBS about the fact that DBS alone will not be sufficient for improved QoL, and participants with more insight are more likely to be active participants in their recovery.

Supporting information

Acknowledgments

The authors would like to acknowledge all the patients from the Neuromodulation and OCD Program who participated in this study. The authors are grateful for the stories and data that these patients provided. The authors would like to also thank Dr. Joseph Sakai for his help with conceptualizing the quantitative data analysis. The authors would also like to thank Hunter Orr for his work editing transcripts for translational related errors.