Despite Appearing Obvious, Link Between Stress and Psoriasis Is Still Not Well Understood

The relationship between stress and psoriasis is recognized by patients and clinicians alike. People with psoriasis experience a significant impairment of their quality of life associated with the stigma of unsightly skin eruptions, and frequently attribute psoriasis outbreaks to high stress events or periods in their lives. The clinical question remains:Is stress a trigger—or at least an exacerbating factor—and if so, how should this influence treatment approaches?

Although a causal link has not been established in randomized clinical trials (RCTs), Heller, et al noted that the majority of patients with psoriasis attributed their symptoms directly to stress, giving it more weight than other possible triggers such as weather, diet, infections, trauma, or medication use.  “Stress may worsen psoriasis severity and may even lengthen the time to disease clearance. Although a pathogenic association appears likely, additional well-controlled studies are necessary to confirm such a causal relationship,” the researchers wrote.1

In a 2018 review of 32,537 patients across 39 studies, Igor Snast, MD, of the department of dermatology, Beilinson Hospital, Rabin Medical Center, Petach Tikva, Israel, and colleagues, determined that 46% of patients associated their psoriasis with stress reactions and 54% made direct associations with triggering stressful events prior to their most recent episode, despite a lack of previous evidence of any impact of stress on exacerbations of psoriasis.2

Both the investigators and a commentary by Frank Dodoo-Schittko, MD  of the Institute of Epidemiology and Preventive Medicine, University of Regensburg in Germany,3 noted important limitations to the conclusions of this review due to the wide heterogeneity of the studies evaluated and a moderate-to-high quality assessment of risk of bias of many of the observational studies used, while many other studies were cross-sectional and did not show a predictive response of psoriasis to stress. The only prospective cohort study included in the review reported a small correlation between stress levels and exacerbation of psoriasis (r=0.28; P <.05), which Snast and colleagues concluded was not convincing of a link.² “Taken together, no clear evidence can be derived from the existing scientific reports,” Dr Dodoo-Schittko wrote.³

Thomas Stewart, MD, of the School of Medicine, University of New South Wales, Sydney, Australia, and colleagues conducted a similar review in 2018 designed to examine a causal relationship between psychological stress and manifestations of psoriasis. Due to the same limitations as in the Snast review, they could not complete a meta-analysis but still identified a consistent pattern of stress-responsiveness to onset of psoriasis across a variety of epidemiologic and case controlled studies.⁴ They pointed to several studies indicating greater disease severity in people with psoriasis reporting high levels of daily stress compared with people reporting lower stress.⁴ They also identified substantial trends in pediatric onset in which stressful life events were reported prior to the diagnosis of psoriasis. Although mental health disorders are associated with higher degrees of stress, none of the included studies evaluated mental health at baseline.⁴

Different Stress Response Levels

Approximately 37% to 78% of people diagnosed with psoriasis in these studies seem to be “stress-responders” and demonstrated lower levels of salivary and serum cortisol when experiencing high stress compared with non-responders.¹

Dr Stewart and others proposed a different underlying response in individuals who experience psoriasis reactions to stressful events or continued life stress that may be