[Alexithymia and psoriasis: a case-control study of 53 patients]

Alexithymia was originally defined as the inability to recognize and verbalize emotions. It is characterized by an emptiness of feelings, poverty of imagination or of a life fantasy and difficulties in communicating with other people, as well as lack of positive emotions and a high prevalence of negative emotions. Its presence has been incriminated in the genesis and in the maintenance of various psychosomatic pathologies. Psoriasis, a frequent dermatitis, is classified among psychosomatic pathologies. In fact, the psychological dimension seems important, either in the appearance of the illness, in its evolution or in its prognosis.

Estimate the prevalence of alexithymia among patients with psoriasis. Study the relationship between them. PATIENTS' CHARACTERISTICS: Fifty-three patients with psoriasis consulted the Dermatology Department of the Hedi Chaker University Hospital, in Sfax, Tunisia. Patients' mean age was 42 years (min: 18 years; max: 76 years). The majority was married (58%), coming from middle to low social economic status (86%), and having a primary or secondary school level (84%). Psoriasis was vulgar for 47 patients (89%) and pustular for the others (11%).

We built a case-control study of 53 patients with psoriasis. The control group was formed of 53 subjects without psoriasis and paired according sex, age and school level. We evaluated psoriasis severity using the Psoriasis Area and Severity Index (PASI), a standardised instrument permitting assessment of the global severity of psoriasis. A cut off of 12 was used to diagnose severe psoriasis. Alexithymia was assessed with the 20-item version of the Toronto Alexithymia Scale (TAS-20). This instrument has shown to be the best validated instrument for measuring alexithymia. A cut off of 61 was used to diagnose alexithymia. Sociodemographical and clinical data were assessed by a questionnaire that was filled in by the doctor conducting the study. All analyses were performed using the SPSS version 11.0 and with a 95% confidence interval. Differences in groups were tested using student's independent t-test, and Chi-square.

The mean score of alexithymia for the patients was 56 (E: 12.1). The mean score of alexithymia for the control group was 45 (E: 9.6). Thirty-nine decimal six percent (n: 21) of patients and 13.2% (n: 7) of controls exhibited alexithymia. Our results confirm the high prevalence of alexithymia among patients with psoriasis (39.6%) compared to controls (13.2%) (p: 0.0002, RR: 3.4). A stress factor was present before the apparition of psoriasis in half of the cases. Psoriasis was severe in 50% of cases. Women with psoriasis (and not men) presented severe psoriasis when they suffered from alexithymia (p: 0.049). The relationship between alexithymia and age was significant from the age of 40 (p: 0.024). The association between psoriasis and another psychosomatic diseases was significantly more important than for the controls (p: 0.03; RR: 4.6). Psoriasis was not correlated to psychoactive substance (tobacco and alcohol, in our study). However, in the group of patients with alexithymia, alcohol consumption was associated with psoriasis severity (p: 0.05).

In alexithymia, there is a risk that physical and emotional feelings will be used without distinction as signs of psychological distress, which can explain the somatic complaint due to the lack of the expression of psychological suffering. This can lead to the apparition of psoriasis. The relationship between psoriasis and alexithymia is increasingly studied in epidemiological surveys that use different instruments to measure alexithymia. However, the results of these surveys do not concord with ours. Our results demonstrated a close link between the two conditions. Moreover, the risk of further psychosomatic diseases increases in the presence of alexithymia. The consumption of alcohol was also high in cases of severe forms of psoriasis.

Alexithymia does not appear to be a simple condition, related to psoriasis, but a worsening of the condition, exposing the patient to the association of other psychosomatic diseases and alcoholism, and thus worsening the global prognosis of these patients. The psychological approach, which favours the expression of emotions and permits a symbolic dimension, is as important as the biological approach, and necessary for the improvement of these patients.