Previous studies have found a potential link between autoimmune diseases, such as psoriasis, and the risk of developing dementia later in life. Despite findings of a risk association between such conditions and dementia, there has been no data to suggest that autoimmune diseases like psoriasis cause dementia, and how these autoimmune diseases affect the brain is not fully understood.1-4 Still, the question remains: is there a link between autoimmune diseases like psoriasis and dementia?
The link between dementia and psoriasis
Several early reports have shown a potential link between psoriasis and dementia. Still, these studies have been usually small or did not include follow-up.1-4 The most recent study showing a relationship between psoriasis and dementia—as well as several other autoimmune diseases—did find a significant connection between patients with psoriasis and the development of dementia later on. In this study, psoriasis was associated with a 29% increased risk of dementia. The biggest impact found seemed to be on vascular dementia. Vascular dementia is caused by conditions that block or reduce blood flow to the brain, which could be related to the autoimmune effect on the circulatory system. Chronic inflammation may also play a role.4
Though the association was found to be significant, what was unclear was what role other conditions may have also played in the development of dementia.4
Recent data, however, suggests that in fact, there is no correlation between psoriasis and cognitive impairment—a common symptom of dementia—nor increased dementia risk. This new study compared cognitive function or mild cognitive impairment with patients both with and without psoriasis. The population-based study found that cognitive impairment did not differ between patients with or without psoriasis. Similarly, in the follow-up group, there did not appear to be a relationship between having psoriasis and developing dementia later in life.5,6
A possible protective effect
Interestingly, in this most recent study, psoriasis was actually associated with a significantly lower risk of dementia. The findings also further suggested psoriasis may have a possible protective effect against dementia, which could be related to the medications used to treat the symptoms of psoriasis.5,6
With research this conflicting, scientists agree that further study is needed to examine the potential connection between psoriasis and dementia, along with autoimmune diseases in general. While there could be a connection, there could also be a protective association.1,5 Patients and doctors should be aware of the potential connection and stay tuned for further research findings.
Wotton CJ, Goldacre MJ. Associations between specific autoimmune diseases and subsequent dementia: retrospective record-linkage cohort study, UK. J Epidemiol Community Health. 2017;71:576-583.
Colgecen E, Celikbilek A, Keskin DT. Cognitive impairment in patients with psoriasis: a cross-sectional study using the Montreal Cognitive Assessment. Am J Clin Dermatol. 2016;17:413-419.
Gisondi P, Sala F, Alessandrini F, et al. Mild cognitive impairment in patients with moderate to severe chronic plaque psoriasis. Dermatology. 2014;228:78-85.
Walsh N. Medpage Today. Dementia risk up with autoimmunity. Risk for patients with autoimmune diseases was 20% higher than for controls. https://www.medpagetoday.com/rheumatology/generalrheumatology/63498. Accessed November 5, 2018.
Pezzolo E, Mutlu U, Vernooij MW, et al. Psoriasis is not associated with cognition, brain imaging markers and risk of dementia: the Rotterdam Study. J Am Acad Dermatol. 2018. [Epub ahead of print].
Lehotzky B. Medpage Today. Psoraisis not linked to higher dementia risk. https://www.medpagetoday.com/resource-centers/contemporary-approaches-psoriasis/psoriasis-not-linked-higher-dementia-risk/2202. Accessed November 5, 2018.