Patients with psoriasis have a higher risk of dementia: A systematic review and meta-analysis

Patients with psoriasis may have a higher risk of dementia because of the higher inflammatory burden, although results from previous epidemiological studies have been inconsistent.

To determine the association between psoriasis and risk of dementia by pooling the evidence from previous studies.

Potentially eligible studies were identified from Medline and EMBASE databases from inception to July 2019 using a search that comprised terms for "psoriasis" and "dementia." Studies were eligible for the meta-analysis if they were cohort studies that included psoriatic patients and individuals without psoriasis and followed them for incident dementia. Studies were also required to report standardized incidence ratio, hazard risk ratio or relative risk with related 95% confidence intervals (CI) comparing the incidence of dementia between the two cohorts. The retrieved point estimates with standard errors from each study were pooled into the final result by the random-effect model, generic inverse variance method.

A total of 8,861 articles were identified. After two rounds of independent review by three investigators, we included six cohort studies that met the eligibility criteria in the meta-analysis. The risk of dementia was significantly higher among psoriatic patients than in those without psoriasis with a pooled risk ratio of 1.16 (95% CI, 1.04-1.30; I2 95%). A funnel plot was relatively symmetric and was not suggestive of the presence of publication bias.

Limited accuracy of diagnosis of psoriasis and dementia as four included studies were coding-based studies, and high statistical heterogeneity among studies.

This systematic review and meta-analysis indicates that psoriatic patients have a significantly elevated risk of developing dementia.