Study Explores Psoriasis-Dementia Link

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Psoriasis is a prevalent disorder affecting approximately 2% of the population.¹ Dementia, a syndrome encompassing a decline in cognitive functions such as memory, reasoning, has a global prevalence projected to increase from 50 million cases in 2018 to 150 million by 2050.² While 45% of dementia cases are attributed to modifiable risk factors, many underlying causes remain elusive.³

Background

Substantial evidence connects higher levels of inflammatory markers with Alzheimer’s disease, a specific form of dementia, as well as vascular dementia.⁴ Both conditions highlight the potential role of systemic inflammation in cognitive decline. Notably, psoriasis and dementia share commonalities such as disrupted sleep and potential circadian dysregulation, which may indicate overlapping pathophysiological pathways.^5,6 Despite this, the relationship between psoriasis and dementia remains inconclusive, with existing studies presenting conflicting findings.^7,8

An important consideration in understanding the psoriasis-dementia relationship is the severity of psoriasis and its treatment. Evidence indicates that dementia risk may increase with greater psoriasis severity, potentially implicating more pronounced systemic inflammation as a causal factor.⁹ However, most studies have inadequately accounted for potential confounders, such as comorbidities, lifestyle factors, or socioeconomic status.

Methods and Materials

A recent cohort study sought to address these gaps by investigating the association between psoriasis and all-cause dementia risk in a large population-based cohort using electronic health records from English primary and secondary care systems. This study included over 346,000 individuals with psoriasis matched with approximately 1.7 million individuals without psoriasis. Participants were followed for an average of 6.9 years. The primary outcome was the occurrence of all-cause dementia, with secondary analyses examining Alzheimer’s disease and vascular dementia specifically.¹⁰

Results

Findings indicated that individuals with psoriasis had a slightly elevated hazard of developing dementia compared to those without psoriasis. The hazard ratio (HR) for all-cause dementia was 1.06 (95% CI 1.04-1.08). However, when dementia subtypes were analyzed, the association was stronger for vascular dementia (HR 1.10, 95% CI 1.06–1.14) than for Alzheimer’s disease (HR 1.03, 95% CI 1.00–1.06). Notably, the risk of dementia increased with time since psoriasis diagnosis, particularly beyond 15 years.

The study found the severity of psoriasis also played a role. Individuals with severe psoriasis exhibited significantly higher risks of vascular dementia (HR 1.49, 95% CI 1.36–1.62) compared to those with mild psoriasis or the general population. Interestingly, severe psoriasis was not strongly associated with Alzheimer’s disease risk (HR 1.09, 95% CI 1.01–1.18). Researchers stated these findings suggest that vascular pathways rather than neurodegenerative processes may primarily link psoriasis with dementia.

The study found sensitivity analyses reinforced these results, showing consistent findings across various adjustments for confounders such as frailty, comorbidities, and healthcare utilization. Additionally, the inclusion of sleep problems as a potential mediator revealed minimal impact on the primary associations, suggesting that systemic inflammation and vascular health may be more critical.

The study’s strengths included its large, population-based cohort and comprehensive use of linked health records, which minimized selection bias. However, researchers noted limitations included potential misclassification of dementia diagnoses, as not all individuals with dementia receive a formal diagnosis. Furthermore, increased healthcare contact among individuals with psoriasis could lead to detection bias, though this was addressed through adjustment for healthcare utilization.

Conclusion and Future Research

Researchers stated the findings suggest a modest but significant association between psoriasis, particularly severe forms, and an increased risk of vascular dementia. These results highlight the importance of managing systemic inflammation and monitoring cognitive health in individuals with psoriasis, particularly those with severe disease. They suggested future research should explore targeted interventions to mitigate dementia risk in this population, as well as investigate the underlying mechanisms linking these 2 conditions.

References

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2. Patterson C. Alzheimer's Disease International. World Alzheimer report 2018: The state of the art of dementia research: New frontiers. 2018. Accessed January 20, 2025. https://www.alzint.org/resource/world-alzheimer-report-2018/
3. Livingston G, Huntley J, Liu KY, et al. Dementia prevention, intervention, and care: 2024 report of the Lancet standing Commission. Lancet. 2024;404(10452):572-628. doi:10.1016/S0140-6736(24)01296-0
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5. Uddin MS, Tewari D, Mamun AA, et al. Circadian and sleep dysfunction in Alzheimer's disease. Ageing Res Rev. 2020;60:101046. doi:10.1016/j.arr.2020.101046
6. Gupta MA, Simpson FC, Gupta AK. Psoriasis and sleep disorders: A systematic review. Sleep Med Rev. 2016;29:63-75. doi:10.1016/j.smrv.2015.09.003
7. Wu CY, Hu HY, Chou YJ, et al. Psoriasis is not a risk factor for dementia: a 12-year nationwide population-based cohort study. Arch Dermatol Res. 2020;312(9):657-664. doi:10.1007/s00403-020-02057-2
8. Huang J, Su B, Karhunen V, et al. Inflammatory diseases, inflammatory biomarkers, and Alzheimer disease: An observational analysis and mendelian randomization. Neurology. 2023;100(6):e568-e581. doi:10.1212/WNL.0000000000201489
9. Zhao J, Li T, Wang J. Association between psoriasis and dementia: A systematic review. Neurologia (Engl Ed). 2024;39(1):55-62. doi:10.1016/j.nrleng.2023.12.005
10. Matthewman J, Mansfield KE, Cadogan SL, et al. Psoriasis and dementia: A population-based matched cohort study of adults in England. Ann Clin Transl Neurol. 2025. doi:10.1002/acn3.52283