Depression

Depressive disorders are marked by sadness, emptiness, irritability, somatic (e.g., poor sleep and appetite) and cognitive (e.g., poor concentration) features that interfere with an individual’s ability to function. Specifically, major depressive disorder (MDD) as a psychiatric diagnosis is characterized by at least 2 weeks of changes in affect, cognition, and neurovegetative functions. In the United States, the 12-month prevalence of MDD is approximately 7%, and MDD is an established comorbidity of chronic pain.

To date, studies examining the psychiatric burden of HS have primarily focused on the prevalence of depression, and less on anxiety or other psychiatric disorders. Depression has been identified as an important comorbidity of HS in a number of studies, but results of studies examining the prevalence of depressive symptoms have been mixed. A recent meta-analysis of 28 studies of depression in HS found a prevalence of 21% and that HS patients were twice as likely to have depression compared to controls. In a retrospective analysis of new-onset depression in HS patients based on electronic health records data ( n = 49,280 for adult HS patients and 3,042 for pediatric HS patients), depression incident rates of 4.8 per 100 person-years in the adult population and 3.0 per 100 person-years in the pediatric population were reported.

Research has confirmed that feelings of shame, stigma, embarrassment, social isolation, and pain can contribute to depressive symptoms in HS. Since HS patients experience at least one, and often several, of these factors on a daily basis, it is not difficult to understand how depressive symptoms may evolve and intensify over the course of the disease. For instance, in one study ( n = 94), HS patients demonstrated significantly higher scores than healthy controls with respect to depression (5.45 vs. 4.16) and loneliness (UCLA Loneliness Scale: 42.8 vs. 35.57), as well as significantly lower self-esteem (Rosenberg Self-Esteem Scale: 18.91 vs. 19.77).

Suicide

In general, thoughts of death, suicidal ideation, and suicide attempts are common in individuals suffering from MDD. Given that depressive symptoms disproportionately affect HS patients as previously discussed, the risk of suicide for those suffering from this chronic inflammatory disease merits attention. Furthermore, chronic pain, a clinical hallmark of HS, can compound the suicide risk in HS.

A population-based study in the United States ( n = 49,380 HS patients and approximately 23 million non-HS controls) found the absolute risk of completed suicide to be 0.8% in HS compared with 0.3% in the control population. After adjusting for age, gender, and race, the authors reported that HS patients had a significantly increased risk of suicide compared to those without HS (OR: 2.88). The risk of suicide in HS correlated with advancing age, and was the highest in individuals aged 60 or older (OR: 3.62).

A Danish cohort and cross-sectional study ( n = 7,732 HS patients and 4,354,137 background population) corroborated the above findings from the U.S. study regarding the risk of completed suicide in HS. They found a significantly increased risk of completed suicide (adjusted hazard ratio [HR]: 2.42) and antidepressant use (adjusted HR: 1.30) in the HS cohort compared to the background population. Suicidality might not always be apparent, so we recommend screening as appropriate by all members of the interdisciplinary HS care team.

Anxiety

A small number of studies have examined anxiety as an associated psychiatric comorbidity of HS. Anxiety disorders are defined by excessive fear and anxiety along with related behavioral disturbances. They can be further categorized as panic disorder, social anxiety disorder, agoraphobia, or generalized anxiety disorder. Fear of disease flare-ups, malodourous discharge, soiling of clothing from bleeding/exudation, and financial distress have been postulated to exacerbate symptoms of anxiety in HS. In a recently published meta-analysis of 12 studies, the authors found a prevalence of 12% and a nearly two-fold risk of anxiety among HS patients relative to controls.

Bipolar Disorder, Psychosis, and Personality Disorders

Few studies have examined the prevalence of other psychiatric diagnoses, such as bipolar disorder, schizophrenia, or personality disorders. An Israeli cross-sectional study ( n = 4,191 HS patients and 20,941 matched controls) found a significantly higher prevalence of schizophrenia in the HS cohort than the control group (1.4% vs. 0.4%). Analysis of a Finnish registry found that HS patients have a significantly increased risk of being diagnosed with at least one psychiatric comorbidity compared to psoriasis (PSO) patients (OR: 1.34) or those with melanocytic nevi (MN) (OR: 2.04). Respectively, the authors found a significantly higher prevalence of schizophrenia, bipolar disorder, and personality disorders in the Finnish HS population relative to their matched psoriasis and MN controls.

These findings do not indicate causality and need to be further explored. We encourage dermatologists to assess patients for mental health disorders, including those on the psychosis spectrum, as early diagnosis and referral to treatment can be life-changing. They may even enhance adherence to medical therapy and thus affect treatment outcomes for HS patients.

Alcohol

The proportion of SUD cases among HS patients that are attributed to alcohol abuse was reported to be as high as 47.9% in the aforementioned U.S. cross-sectional study. In another study, 27,725 blood donors from Denmark were queried about their drinking habits. Significantly greater proportions of participants with HS reported wine and spirits consumption relative to non-HS participants. There was no significant difference in beer consumption habits between those with and without HS. The authors did not control for psychiatric comorbidities, such as depression, or socioeconomic factors. Moderate depression was found to be significantly more prominent in the HS group (3.2%) than the non-HS group (0.7%), which could have contributed to increased alcohol consumption by HS patients.

A single-center study reported an increased risk of alcohol dependence among HS patients; however, after adjusting for psychiatric comorbidities and other confounding variables, HS patients actually had smaller odds of alcohol dependence compared with the control group. Two case-control studies relying on patient-level data were not able to demonstrate any association between HS and alcohol dependence. Future research with large and well-controlled studies on alcohol dependence and HS is warranted.

Opioids

The Diagnostic and Statistical Manual of Mental Disorder (DSM)-5 publication characterizes opioid use disorder (OUD) along a mild-moderate-severe spectrum, on which a patient’s seeking behavior progresses despite multiple deleterious consequences to their personal and professional lives. In determining whether HS patients are at an inherent risk for OUD, several confounding factors must be taken into account. Given that pain is a hallmark feature of HS, opioids and other forms of pain control have been prescribed to patients suffering from the disease.

Few studies have addressed the incidence and management strategies of OUD in HS. The proportion of SUD cases attributable to opioids has been reported as 32.7% in the US-based cross-sectional analysis. In addition, a separate retrospective cohort study involving over 20,000 HS patients found them to be at a significantly increased risk (adjusted OR: 1.53) of developing new long-term opioid use relative to controls. Certain risk factors, such as advancing age, ever smoking, history of depression, and baseline Charlson comorbidity index score, were correlated with higher odds of OUD development in HS.

We recommend thorough screening for SUD in HS patients and paying special attention to pain management. Over-prescribing opioids to appease patients without adequately assessing their pain control needs could lead to opioid tolerance and dependence in HS. Undertreating pain for fear of inducing opioid addiction can create a cycle of uncontrolled pain, which in turns exacerbates opioid-seeking behavior. Early referral of patients with chronic or recalcitrant pain to pain management specialists is recommended. A mental health specialist may need to be involved to address any underlying psychosocial component that may predispose a patient to opioid misuse. A multi-disciplinary strategy to address OUD may help preserve physician-patient rapport and improve patient adherence to medical therapy.

Cannabinoids

Few studies have shown increased cannabis use among patients with HS. Cannabis accounted for up to 29.7% of SUD cases in the above-referenced US cross-sectional study. A retrospective French study reported a significant difference between the prevalence of cannabis use in the HS cohort (34.0%) during the past 12 months compared to the psoriasis cohort (11.6%). The cannabis users in this study consisted mostly of young men with lower body mass indexes. Of note, both HS and psoriasis participants reported pleasure as the first motivation for cannabis use, not pain control, and the majority of the HS group (69.4%) had begun using cannabis prior to disease onset. Within the HS group, the researchers found no significant differences in Hurley stage, DLQI scores, or disease course between cannabis users and nonusers. Interestingly, cannabis users reported a significantly higher VAS pain score during disease remission periods than nonusers (1.7 vs. 1.1), while there was no statistically significant difference in pain scores between the two groups during disease flares. The level of addiction to cannabis was significantly higher in the HS group compared with the psoriasis group (Cannabis Abuse Testing Score: 8.4 vs. 4.1). These studies highlight the need for further research on cannabis use in HS patients.

Sleep Disturbance and Daytime Somnolence

In the literature and our clinical experience, HS patients often report sleep disturbance and daytime somnolence. Recent studies have shown that pain and pruritus are major contributors to poor sleep quality. Components of sleep that are affected in HS patients include sleep latency, duration, and disturbance. The authors of a cross-sectional Polish study with over 100 HS patients and 50 healthy controls found that HS patients had a significantly more impaired sleep quality score relative to healthy controls. Severities of pruritus and pain as measured by VAS scores were positively correlated with insomnia scores. These findings are in line with what we have learned from other skin conditions (e.g., atopic dermatitis), where pruritus can lead to disrupted sleep patterns. Activities of daily life may be impacted by two independent factors: pruritus alone, or daytime somnolence as a result of insomnia.

Disutility and Loss of Work Productivity

HS patients often face challenges involving disutility and loss of work productivity. HS typically appears during the second and third decades of life and thus has the potential to negatively impact patients’ early career trajectories. Studies have shown that HS patients missed more workdays than the general public, with one study reporting up to an average work loss of 33.6 days per year. At 2-year follow-up, 23% of the study participants believed that HS negatively impacted their chance for a promotion, and 10% reported losing their jobs due to HS.

A retrospective study investigated a claims database of employed HS patients in the United States. The researchers found that newly diagnosed HS patients experienced a slower income growth and were significantly more likely to leave the work force than controls. HS patients demonstrated statistically significant differences compared to controls in the following metrics: more work loss days (18.4 vs. 7.7), higher annual indirect costs ($2,925 vs. $1,483), and lower annual income ($54,925 vs. $62,357).

Challenges to Implementing Lifestyle Modifications

HS patients often face physical and social barriers, which may hinder their ability to implement positive lifestyle changes. HS has been linked to obesity and active smoking. Despite their deleterious health effects, tobacco usage and overeating are ways in which some patients cope with the stress associated with HS. In a qualitative Danish focus-group study, patients reported feeling that HS and its symptoms are outside their control. As such, they considered any long-term lifestyle modifications as futile.

Studies have shown that appropriate weight loss and smoking cessation can improve the overall health of HS patients. However, in addition to feeling a lack of control over their health, chronic pain often prevents patients from engaging in activities that can help promote weight loss, such as exercising or participating in sports. Moreover, embarrassment and fear of judgment could prevent HS patients from forming healthy social interactions. The aforementioned qualitative study also found that HS patients reported feeling alone regarding their disease and would like the opportunity to meet or have online contact with other HS patients.

Empowering patients to be partners in managing their HS disease may lead to enhanced care outcomes. In addition, encouraging HS patients to explore patient-led groups for social support and sharing of resources may promote a sense of community among them. HS support groups are discussed in detail in Chapter 33 .