How Can Psoriasis, Depression Impact the Brain?

Georgia Lada, MD

New research examined brain structure and connectivity in patients to observe the effects of psoriasis in relation to depression. Depression coexists with psoriasis in up to 25% of patients.

According to Georgia Lada, MD, Dermatology Centre, Salford Royal NHS Foundation Trust, National Institute for Health Research Manchester Biomedical Research Centre, The University of Manchester, and her team, an immune-mediated relationship between the brain and skin has been hypothesized in psoriasis before.

This brain imaging study was the first to look at the position of depression and systemic inflammation in brain measures while including the largest sample of patients with psoriasis to date.

Understanding Inflammation & Depression

Data of 1048 brain magnetic resonance imaging (MRI) cases from the UK Biobank were assessed. Study populations included 131 comorbid patients with psoriasis and depression, who were matched by age and sex to 131 non-depressed patients with psoriasis. Then, 393 patients with depression served as a control group, along with 393 non-depressed controls.

"Interaction effects of psoriasis and depression on volume, thickness and surface of a-priori defined regions of interest (ROIs), white matter tracts and 55x55 partial correlation resting-state connectivity matrices were investigated using general linear models," investigators wrote. "Linear regression was employed to test associations of brain measures with C-reactive protein (CRP) and neutrophil counts."

MRI Results & Brain Connectivity

With the presence of depression, increased thickness in the right precuneus was evident in patients with psoriasis compared with controls. This thickening demonstrated a marginal correlation with recurrent lifetime suicidality in patients with depression and psoriasis.

Findings revealed no differences in regional, global brain volumes, or white matter integrity compared with controls without psoriasis or psoriatic arthritis (PsA). Unrelated to depression comorbidity, patients with coexisting psoriasis and PsA showed fronto-occipital decoupling in resting-state connectivity compared to patients without joint involvement and controls.

Investigators reported that CRP and neurophil counts did not predict precuneus thickness and fronto-occipital connectivity.

"Our findings provide evidence for a combined effect of psoriasis and depression on the precuneus, which is not directly linked to systemic inflammation, and may relate to suicidality or altered somatosensory processing," the team concluded. "The use of the UK Biobank may limit generalizability of results in populations with severe disease."

The study "Brain structure and connectivity in psoriasis and associations with depression and inflammation; findings from the UK biobank" was published in Brain, Behavior, & Immunity Health.