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Table 1.  Characteristics of the Psoriasis Cohort and the General Population Comparison Cohort
Characteristics of the Psoriasis Cohort and the General Population Comparison Cohort
Table 2.  Incidence Rates and HRs of Mental Disorders Among Individuals With Psoriasis Compared With the General Population Cohort
Incidence Rates and HRs of Mental Disorders Among Individuals With Psoriasis Compared With the General Population Cohort
1.
Kurd  SK, Troxel  AB, Crits-Christoph  P, Gelfand  JM.  The risk of depression, anxiety, and suicidality in patients with psoriasis: a population-based cohort study.  Arch Dermatol. 2010;146(8):891-895.PubMedGoogle Scholar
2.
Brandrup  F, Green  A.  The prevalence of psoriasis in Denmark.  Acta Derm Venereol. 1981;61(4):344-346.PubMedGoogle Scholar
3.
Benros  ME, Waltoft  BL, Nordentoft  M,  et al.  Autoimmune diseases and severe infections as risk factors for mood disorders: a nationwide study.  JAMA Psychiatry. 2013;70(8):812-820. doi:10.1001/jamapsychiatry.2013.1111PubMedGoogle ScholarCrossref
4.
Leboyer  M, Oliveira  J, Tamouza  R, Groc  L.  Is it time for immunopsychiatry in psychotic disorders?  Psychopharmacology (Berl). 2016;233(9):1651-1660. doi:10.1007/s00213-016-4266-1PubMedGoogle ScholarCrossref
5.
Gisondi  P, Sala  F, Alessandrini  F,  et al.  Mild cognitive impairment in patients with moderate to severe chronic plaque psoriasis.  Dermatology. 2014;228(1):78-85. doi:10.1159/000357220PubMedGoogle ScholarCrossref
6.
Abuabara  K, Azfar  RS, Shin  DB, Neimann  AL, Troxel  AB, Gelfand  JM.  Cause-specific mortality in patients with severe psoriasis: a population-based cohort study in the UK.  Br J Dermatol. 2010;163(3):586-592. doi:10.1111/j.1365-2133.2010.09941.xPubMedGoogle ScholarCrossref
Research Letter
May 8, 2019

Psoriasis and Risk of Mental Disorders in Denmark

Author Affiliations
  • 1Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark
  • 2Department of Dermatology, Aarhus University Hospital, Aarhus, Denmark
  • 3Department of Clinical Medicine, Aarhus University Hospital, Aarhus, Denmark
  • 4Department of Affective Disorders, Department of Psychiatry, Aarhus University Hospital, Aarhus, Denmark
  • 5Aarhus Institute of Advanced Studies, Aarhus University, Denmark
  • 6Department of Radiology, Aarhus University Hospital, Aarhus, Denmark
JAMA Dermatol. 2019;155(6):745-747. doi:10.1001/jamadermatol.2019.0039

Psoriasis has been reported to be associated with an elevated risk of various mental disorders, including depression, anxiety, and suicidality.1 However, to our knowledge, no studies have determined the long-term risk of a broader spectrum of adult-onset mental disorders in a large cohort of individuals with psoriasis. Given the high prevalence of psoriasis—between 2% and 4% in adults2—investigation of the association of this condition with mental health has important public health implications. Therefore, we aimed to elucidate the association between psoriasis and the entire spectrum of adult-onset psychiatric morbidity. The study was approved by the Danish Data Protection Agency, whose role is to protect the privacy of individuals whose data are recorded in Danish registries. No informed consent was required for this study.

Methods

We used data from population-based registries covering all Danish hospitals to identify individuals born from 1900 to 1995 who had at least 2 hospital- or outpatient-based diagnoses of psoriasis from January 1, 1977, to January 1, 2012. Using the Danish Civil Registration System, we identified 10 population-comparison cohort members matched on sex and birth year. Follow-up was continued until diagnosis of a mental disorder, death, emigration, or end of the study (January 1, 2013). Only diagnoses of mental disorders made at either inpatient or outpatient facilities were considered (as registered in the Danish Central Psychiatric Research Register). Data analysis was performed from January 1 to March 1, 2017.

To test the association between psoriasis and subsequent development of mental disorder, we computed cumulative incidences accounting for death as a competing risk, incidence rates, and calculated hazard ratios (HRs) of time to diagnosis of any mental disorder, as well as specific mental disorders, adjusting for birth year and sex. We also performed subgroup analyses according to educational level (short-term, medium-term, long-term) of patients with psoriasis. Furthermore, comorbidities were identified to evaluate the association of these conditions with the development of mental disorders among individuals with psoriasis. Statistical analysis was performed with Stata, version 14 (StataCorp).

Results

We identified 13 675 individuals with psoriasis (50% male) (Table 1). The 5- and 10-year cumulative incidences of any mental disorder were 2.6% and 4.9%, respectively. The HR of any mental disorder was 1.75 (95% CI, 1.62-1.89) when comparing those with psoriasis with the general population cohort (Table 2). The HRs for selected mental disorders were as follows: 1.73 (95% CI, 1.21-2.47) for vascular dementia, 1.64 (95% CI, 1.01-2.65) for schizophrenia, 2.33 (95% CI, 1.59-3.41) for bipolar disorder, 1.72 (95% CI, 1.49-1.98) for unipolar depression, 1.88 (95% CI, 1.08-3.30) for generalized anxiety disorder, and 2.06 (95% CI, 1.55-2.73) for personality disorders. The risk of mental disorders among individuals with psoriasis who had completed short-term education presented with an HR of 2.18 (95% CI, 1.95-2.44), while those who had attained medium- and long-term educational levels demonstrated HRs of 1.45 (95% CI, 1.26-1.67) and 1.40 (95% CI, 1.11-1.78), respectively.

Discussion

Our findings are in agreement with those of previous research, indicating a higher risk of depression among individuals with psoriasis.1 Furthermore, our findings suggest a higher risk of bipolar disorder among those with psoriasis than among matched controls. To our knowledge, no studies have evaluated bipolar disorder in the context of psoriatic pathogenesis; however, a heightened risk of bipolar disorder among individuals with psoriasis is in line with hypotheses suggesting an inflammation-mediated induction and/or progression of bipolar disorder.3 Similarly, immune dysregulation has been suggested to play a pivotal role in schizophrenia.4 We also found an increased risk of vascular dementia among individuals with psoriasis. It has been reported that the prevalence of mild cognitive impairment is higher among individuals with psoriasis5 and that the risk of death due to dementia may be elevated among individuals with psoriasis.6 However, to our knowledge, no previous, larger studies have determined the risk of dementia within this patient population. The findings reported herein support the need for an approach when treating individuals with psoriasis that focuses not only on their dermatologic condition, but also on their mental health.

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Article Information

Accepted for Publication: January 3, 2019.

Corresponding Author: Michelle Z. Leisner, MPH, Department of Clinical Epidemiology, Aarhus University Hospital, Olof Palmes Allé 43-45, 8200 Aarhus N, Denmark (michelle.leisner@clin.au.dk).

Published Online: May 8, 2019. doi:10.1001/jamadermatol.2019.0039

Author Contributions: Ms Leisner and Dr Olsen had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Lindorff Riis, Schwartz, Dinesen Østergaard, Olsen.

Acquisition, analysis, or interpretation of data: Leisner, Iversen, Dinesen Østergaard, Olsen.

Drafting of the manuscript: Leisner.

Critical revision of the manuscript for important intellectual content: All authors.

Statistical analysis: Olsen.

Obtained funding: Lindorff Riis.

Administrative, technical, or material support: Leisner.

Supervision: Leisner, Lindorff Riis, Iversen, Dinesen Østergaard, Olsen.

Conflict of Interest Disclosures: Dr Lindorff Riis reported grants from Psoriasisforskningsfonden during the conduct of the study. Dr Iversen reported grants from the Danish Research Council and grants from Novo Nordic Foundation during the conduct of the study; grants and personal fees from Novartis, grants and personal fees from Leo Pharma; and personal fees from Eli Lilly, Janssen, Almirall, UCB, Pfizer, AbbVie, and BMS outside the submitted work. Dr Dinesen Østergaard reports a patent for “Use of sortilin as biomarker for affective/mood disorders” (WO2015121166A1) pending and with royalties paid. No other disclosures were reported.

Funding/Support: The study was supported by a grant from Psoriasis Forskningsfonden.

Role of the Funder/Sponsor: Psoriasis Forskningsfonden had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

References
1.
Kurd  SK, Troxel  AB, Crits-Christoph  P, Gelfand  JM.  The risk of depression, anxiety, and suicidality in patients with psoriasis: a population-based cohort study.  Arch Dermatol. 2010;146(8):891-895.PubMedGoogle Scholar
2.
Brandrup  F, Green  A.  The prevalence of psoriasis in Denmark.  Acta Derm Venereol. 1981;61(4):344-346.PubMedGoogle Scholar
3.
Benros  ME, Waltoft  BL, Nordentoft  M,  et al.  Autoimmune diseases and severe infections as risk factors for mood disorders: a nationwide study.  JAMA Psychiatry. 2013;70(8):812-820. doi:10.1001/jamapsychiatry.2013.1111PubMedGoogle ScholarCrossref
4.
Leboyer  M, Oliveira  J, Tamouza  R, Groc  L.  Is it time for immunopsychiatry in psychotic disorders?  Psychopharmacology (Berl). 2016;233(9):1651-1660. doi:10.1007/s00213-016-4266-1PubMedGoogle ScholarCrossref
5.
Gisondi  P, Sala  F, Alessandrini  F,  et al.  Mild cognitive impairment in patients with moderate to severe chronic plaque psoriasis.  Dermatology. 2014;228(1):78-85. doi:10.1159/000357220PubMedGoogle ScholarCrossref
6.
Abuabara  K, Azfar  RS, Shin  DB, Neimann  AL, Troxel  AB, Gelfand  JM.  Cause-specific mortality in patients with severe psoriasis: a population-based cohort study in the UK.  Br J Dermatol. 2010;163(3):586-592. doi:10.1111/j.1365-2133.2010.09941.xPubMedGoogle ScholarCrossref
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