Psychological aspects of patients with psoriasis: Biological and clinical studies

Psychological distress is well known to be associated with psoriasis, both as a disease consequence, and as a causative factor for onset and exacerbations. Psychoneuroimmunological mechanisms have been suggested to be involved in the pathogenesis of psoriasis and have often been shown to be related to psychological distress and pruritus in psoriasis.
The general aim of this thesis was to investigate psychoneuroimmunological and psychological aspects of patients with plaque psoriasis and to identify potentially psychologically vulnerable individuals by means of clinical characteristics.
In Paper I, a significantly increased immunohistological expression of the neuropeptide substance P (SP) and its receptor neurokinin-1 (NK-1R) was found in involved psoriatic skin compared with non-involved (n = 13). The expression of SP and NK1-R was, however, not associated with levels of pruritus. The degree of chronic stress indicated by salivary cortisol was significantly associated with increased expression of SP and NK1-R in non-involved psoriatic skin.
Papers II-IV are based on individual psychosocial interviews and three psychometric validated questionnaires (Swedish Universities Scales of Personality, Spielberger State-Trait Anxiety Inventory and Beck Depression Inventory-II) from 101 consecutively recruited patients with psoriasis. Three subgroups of patients with an increased psychological vulnerability could be identified:
Early age at onset of psoriasis, but not disease duration, was significantly associated with pessimistic personality traits and higher scores of anxiety and depression, compared with late onset psoriasis (Paper II). Patients with higher levels of pruritus showed primarily higher scores of depression and also higher scores of anxiety and negative pessimistic personality traits compared with patients with mild pruritus (Paper III). Sixty-four patients (63 %) reported a subjective association between disease exacerbation and stress, and were defined as “stress reactors” (SRs). SRs showed a significantly more vulnerable and stress susceptible personality profile and higher scores of both depression and anxiety, compared with non-stress reactors (Paper IV).
In conclusion, our results indicate that neuroimmunological pathways involving SP may play a key role in psoriasis. From a clinical perspective, our results suggest that when meeting patients with psoriasis, health care professionals should be more attentive to potential psychological vulnerability in patients with young age at onset, and/or severe pruritus, and/or patients who experience disease exacerbation during stress.