A skin condition that takes its toll on your nerves, but it is not a sure-fire route to depression

Anyone who lives with urticaria that comes and goes in waves over weeks or months, in an unpredictable manner and for no apparent reason, knows full well how stressful this can be. And for years, the scientific community has suspected that chronic spontaneous urticaria, a dermatological condition, might be associated with a heavy psychiatric burden: depression, anxiety and even an increased risk of suicidal thoughts. But now a study recently published in Acta Dermato-Venereologica has partly allayed these concerns, providing a more accurate and, in some respects, more reassuring picture.

The research team, led by Ralf J. Ludwig of the Institute of Experimental Dermatology in Lübeck (Germany), set out to investigate what happens following a diagnosis of chronic urticaria, rather than merely capturing a snapshot of a patient’s psycho-emotional state at a given moment. And this makes all the difference. The authors explain that previous studies were often based on cross-sectional analyses, i.e. they took a snapshot of patients already diagnosed with chronic spontaneous urticaria, without, however, being able to establish whether the psychological distress was a cause or a consequence of the dermatological condition. This is a problem described in technical terms as ‘reverse causality’, compounded by what is known as ‘surveillance bias’: those with a chronic illness visit their doctor more often, and therefore have more opportunities to receive a psychiatric diagnosis as well, simply because they are monitored more closely and frequently.

To overcome these limitations, the German researchers drew on the TriNetX database, which contains the medical records of millions of American patients, identifying over 102,000 adults with a recent diagnosis of chronic spontaneous urticaria and no psychiatric history, to compare them with people without this skin condition. Using a statistical method (propensity score matching) that enables the identification and comparison of two groups that are as homogeneous as possible in terms of age, sex and other baseline characteristics, they were able to define two equivalent cohorts, each comprising almost 99,000 people, whom they then followed for the next three years.

The main finding is that chronic urticaria does not, as a general rule, pave the way for psychiatric illness. Indeed, this study did not reveal an increased risk of depression, schizophrenia, suicidal ideation or suicide attempts in the three years following diagnosis. Instead, a modest but statistically significant increase in the risk of severe stress reactions and adjustment disorders was observed, quantifiable as a 15 per cent increase compared with those without urticaria. The authors emphasise that this figure may even be an underestimate, as other analyses have shown higher values (up to +33 per cent).

A second level of analysis was also of interest, which included patients with psychiatric conditions that predated their diagnosis of urticaria. In this case, the associations with depression and stress-related disorders – previously described in the literature – re-emerged. A comparison of the two types of analysis leads the authors to propose an interpretation that differs from the traditional view: much of the link observed to date between urticaria and psychological distress does not stem from the skin condition itself, but from a pre-existing psychological vulnerability, which the dermatological diagnosis merely serves to bring to light.