The skin as a sentinel organ for neurodegeneration: An underrecognized target for dementia prevention

Summary

Dementia prevention increasingly requires attention to modifiable systemic inflammatory stressors. In older adults, bullous pemphigoid (BP), herpes zoster (HZ), psoriasis, atopic dermatitis (AD), rosacea, prurigo nodularis (PN), and chronic pruritus are not merely disorders limited to the skin; they may signal or amplify neuroimmune vulnerability. Observational studies link BP with dementia and Alzheimer's disease, HZ with incident dementia and vascular cognitive injury, and psoriasis, AD, rosacea, or PN with smaller but biologically plausible cognitive risks. The proposed skin-brain axis integrates cytokine spillover, endothelial activation, blood-brain barrier dysfunction, BP180/ BP230 autoantigen sharing, varicellazoster virus neurotropism and vasculopathy, barrier failure, dysbiosis, itching-induced fragmented sleep, and medication or frailty-related cognitive toxicity. Clinically, cognitive impairment also worsens skin surveillance, hygiene, topical adherence, and recognition of pain, itching, infection, or blistering. Although causality and dementia prevention remain unproven, the evidence justifies proactive dermatological care in older adults and greater cognitive vigilance in older patients with severe inflammatory or pruritic dermatoses. Recombinant zoster vaccination, prompt antiviral therapy, steroid-sparing BP strategies, modern anti-inflammatory treatment for AD, psoriasis, and PN, and systematic attention to sleep, itching, caregiver capacity, and the medication burden are practical, low-regret steps while prospective brain-relevant trials are developed. This translational framework highlights mechanisms clinicians can now interrupt and endpoints investigators can soon measure. We propose that the skin should be recognized as a sentinel organ for neurodegeneration and that dermatological disease represents a potentially modifiable contributor to cognitive decline.

1. Introduction

Population aging has made dementia a defining public-health and geriatric-care challenge. The World Health Organization estimates that the number of adults age 60 years and older will increase from 1.0 billion in 2020 to 1.4 billion in 2030 and 2.1 billion in 2050, while the population age 80 years or older is projected to triple to 426 million over the same period (1,2). Dementia is expanding in parallel: an estimated 57 million people were living with dementia worldwide in 2021, more than 60% of whom were living in low-and middle-income countries, and Global Burden of Disease forecasting suggests that this number may reach 152.8 million by 2050 (3,4). These trends have shifted dementia prevention away from a narrow focus on late-stage neurodegeneration toward cumulative, modifiable stresses across a person's life course. In addition to vascular, metabolic, sensory, and lifestyle risks, prevention frameworks increasingly need to account for peripheral inflammation, infection, sleep disruption, medication toxicity, frailty, and other systemic stressors that may erode cognitive reserve before dementia is clinically established.

The skin is a distinctive entry point into this broader prevention framework because it is visible, accessible, immune-active, and continuously exposed to environmental, microbial, inflammatory, vascular, and neural signals. Aging skin is characterized by impaired barrier repair, xerosis, dysregulated immunity, sensory dysfunction, vascular fragility, and slower wound healing, while cognitive impairment reduces the ability to recognize itching, pain, infection, blistering, adverse effects of medication, or early skin breakdown and it limits adherence to topical regimens (5-7). However, the skin should be considered not only a vulnerable target in dementia care, but also a potential sentinel organ for dementia-related biology. Chronic inflammatory, infectious, autoimmune, and pruritic skin diseases may reveal systemic immune activation, neurovascular stress, fragmented sleep, pain, itching, and frailty-related vulnerability in ways that are directly observable in routine dermatological practice.

This review focuses on inflammatory, autoimmune, infectious, and pruritic dermatoses with emerging dementia-related signals, including bullous pemphigoid (BP), herpes zoster (HZ), psoriasis, atopic dermatitis (AD), rosacea, prurigo nodularis (PN), and chronic pruritus. The strength and directionality of evidence differ substantially across these conditions. BP and HZ currently provide the most distinctive disease-specific signals: BP because of its strong association with dementia and biologically plausible BP180/BP230- related neurocutaneous autoimmunity, and HZ because varicella-zoster virus neurotropism, vasculopathy, antiviral treatment, and zoster vaccination create a temporally discrete and potentially preventable neurocutaneous model. In contrast, psoriasis, AD, rosacea, PN, and chronic pruritus offer more modest, heterogeneous, or hypothesis-generating evidence, although their links with systemic inflammation, itching, sleep loss, a mood disturbance, vascular comorbidity, and the treatment burden remain clinically important.

We have organized the evidence into three clinically testable axes linking skin disease and cognitive vulnerability: neuroinflammation, neurovascular injury, and neurofunctional disruption. The neuroinflammatory axis integrates cytokine spillover, endothelial activation, blood-brain barrier vulnerability, microglial and astrocytic priming, and BP-related autoantigen sharing. The neurovascular axis emphasizes HZ/varicellazoster virus (VZV)-related vasculopathy, endothelial injury, thrombosis, ischemic burden, and vascular cognitive impairment. The neurofunctional axis captures itching, pain, fragmented sleep, sedating or anticholinergic medication exposure, corticosteroid toxicity, infection, frailty, delirium risk, and caregiver-dependent treatment failure. This framework does not assume that treating a skin disease prevents dementia. Rather, it proposes that a dermatological disease can provide visible, modifiable, and research-ready signals through which dermatologists, geriatricians, neurologists, and primary-care clinicians can identify cognitive vulnerability earlier, they can reduce low-regret contributors to brain stress, and they can design prospective studies with brain-related endpoints.

2. Why this issue deserves attention

Dementia is a dominant challenge of population aging, and current prevention frameworks emphasize management of cumulative vascular, inflammatory, sensory, sleep, and lifestyle risks (8,9). At the same time, inflammatory and pruritic dermatoses are common in later life, frequently undertreated in frail patients, and often dismissed as problems of comfort or appearance. This separation is increasingly untenable. A skin-brain axis model proposes bidirectional communication: chronic cutaneous inflammation may contribute to systemic and central neuroimmune activation, whereas cognitive decline impairs barrier care, scratching control, hygiene, treatment adherence, and timely reporting of early blistering, pain, infection, or itching (10).

3. Clinical and interventional signals linking skin disease and cognition

The strongest dermatological signal currently comes from BP, a prototypic inflammatory blistering disorder of late life. A systematic review and meta-analysis found that BP is associated with adverse cognitive outcomes, and observational studies have repeatedly reported increased antecedent dementia in BP cohorts (11,12). Mechanistic plausibility is strengthened by evidence that BP180-related autoimmunity may intersect with neuronal tissue, with higher BP180 autoantibody levels reported in patients with Alzheimer's disease and distinct central nervous system (CNS)-related epitope recognition patterns described in neurodegenerative disease (13,14). Given that BP also causes severe itching, skin breakdown, sleep disruption, infection risk, and corticosteroid exposure, it is a plausible amplifier of cognitive vulnerability in patients who are already frail. Table 1 summarizes the major clinicopathologic associations.

Table 1. Associations between skin diseases and cognitive impairment.

Skin disease	Associated cognitive outcome(s)	Representative evidence	Practical message
BP	All-cause dementia; Alzheimer's disease; broader neurologic comorbidity	Systematic review/meta-analysis and multiple cohort/case-control studies support an association; BP180-related autoimmunity provides biologic plausibility.	Use cognitive screening and delirium-risk review before systemic corticosteroids; align steroid-sparing strategy, topical feasibility, itching control, infection prevention, and caregiver training.
HZ	Incident dementia; vascular cognitive impairment; higher concern after CNS involvement	Population-based cohorts link HZ with subsequent dementia, while antiviral therapy and zoster vaccination are associated with lower risk.	Treat HZ as a sentinel neurocutaneous event when ophthalmic, CNS-involved, or severe; prioritize vaccination, prompt antivirals, pain/ sleep control, and follow-up for delirium or executive decline.
Psoriasis	All-cause dementia; Alzheimer's disease; possible cognitive impairment	Systematic reviews/meta-analyses suggest a modest excess risk, although some studies are heterogeneous or null.	Treat psoriasis as a systemic inflammatory disease and address cardiovascular, mood, and lifestyle comorbidities.
AD	All-cause dementia; neurocognitive burden related to sleep loss, itching, and inflammation	Recent meta-analysis suggests a modest association, but causal inference remains uncertain; symptom burden is substantial.	Use nocturnal itching and fragmented sleep as cognitive biomarkers; track caregiver-reported sleep, simplify topical regimens, and treat inflammation early.
Rosacea	All-cause dementia; Alzheimer's disease	A nationwide Danish cohort found increased risk of dementia and especially Alzheimer's disease; a 2024 commentary highlighted rosacea as an underappreciated dementia-associated dermatosis.	Ask older patients with persistent inflammatory rosacea about memory symptoms, sleep, and medication burden; treat rosacea as a chronic inflammatory disorder rather than a cosmetic condition.
PN/chronic prurigo	Measured cognitive impairment; severe daytime dysfunction; sleep-related cognitive burden	Inpatient data documented cognitive impairment in PN, and phase 2/3 studies confirm profound itching and sleep disturbance as treatable disease domains.	Quantify nocturnal scratching and sleep disruption with diaries or actigraphy when possible; use targeted itching control as a brain-relevant intervention.
Chronic pruritus/xerosis in older adults	Sleep disruption, inattention, low mood, daytime dysfunction; may worsen apparent cognition	High symptom burden and reduced quality of life are consistently documented, especially in older adults.	Perform medication reconciliation, xerosis repair, itching control, and sleep-risk review before escalating sedating or anticholinergic drugs.

Abbreviations: BP, bullous pemphigoid; HZ, herpes zoster; CNS, central nervous system; AD, atopic dermatitis; PN, prurigo nodularis.

Beyond epidemiologic overlap, the BP–dementia signal is biologically unusual because BP180/collagen XVII and BP230/dystonin have neuronal isoforms. In Alzheimer's disease, higher serum BP180 autoantibody levels correlate with more severe dementia, and the epitopes recognized in Alzheimer's disease or multiple sclerosis differ from those typically seen in cutaneous BP, suggesting epitope-specific neurocutaneous immunity rather than simple bystander seropositivity (15,16). This pattern is consistent with a bidirectional model in which neurodegeneration may expose neural BP antigens and prime autoimmunity, while systemic autoantibody and complement activation sustain a frailty-promoting inflammatory state.

HZ provides a second compelling example. Population-based studies suggest that incident HZ, and particularly when the central nervous system is involved, is associated with a higher risk of subsequent dementia, while antiviral treatment may attenuate this association (17,18). Even more provocative are recent vaccine studies showing that zoster vaccination is associated with a lower incidence or delayed diagnosis of dementia in older adults (19-21). These findings do not indicate that recombinant zoster vaccine is a dementia treatment, but they do reinforce the broader principle that prevention of dermatological disease may have neurological relevance. Current immunization recommendations already support 2-dose recombinant zoster vaccination in adults age ≥ 50 years and in immunocompromised adults age ≥ 19 years (22,23).

The mechanistic bridge is also stronger in HZ than in most inflammatory dermatoses because VZV is neurotropic, infects vascular endothelium, and activates inflammasome and amyloid-related pathways. Clinically, complicated HZ should therefore be considered a sentinel neurocutaneous event rather than an isolated rash, and particularly in older adults with delirium, gait decline, or new executive dysfunction.

The association between psoriasis and dementia appears more modest and heterogeneous, and yet the direction of the evidence is generally consistent with a systemic inflammatory link. Systematic reviews and meta-analyses suggest a small excess dementia risk in psoriasis, supported by a nationwide cohort study showing increased risk of Alzheimer's disease (24-26). Likewise, a recent meta-analysis found that AD was associated with all-cause dementia in longitudinal cohorts, although Mendelian randomization did not confirm a clear causal genetic effect (27). Importantly, both psoriasis and AD are now regarded as multisystem inflammatory diseases with important comorbidity implications, and both can produce chronic pruritus, fatigue, poor sleep, anxiety, depression, and reduced physical activity—factors that may worsen cognition even before formal dementia is diagnosed (28-37).

The dermatological spectrum is probably broader than these four entities. In a Danish nationwide cohort, rosacea was associated with increased dementia and especially Alzheimer's disease risk, with higher estimates in patients diagnosed in specialist settings (38,39). Prurigo nodularis also deserves attention: measurable cognitive impairment has been documented in inpatients, and the disorder couples intense IL-31-induced itching to repeated nocturnal arousal, anxiety, and compulsive scratching (40-42). Even when frank dementia is absent, these states can worsen executive function, medication adherence, and day–night behavioral stability in older adults.

4. How a skin-brain inflammatory axis may operate

4.1. Neuroinflammation

The first axis places chronic cutaneous inflammation in direct conversation with the aging brain. Psoriasis, AD, BP, rosacea, and chronic prurigo can export IL- 1β, IL-6, TNF-α, IL-17A/F, IL-23, IL-4, IL-13, IL- 31, TSLP, and IL-33 into systemic circulation, where endothelial activation and blood-brain barrier (BBB) vulnerability can amplify microglial and astrocytic responses (10,28,30,34,43). BP adds a disease-specific autoimmune trigger: neuronal isoforms of BP180/ collagen XVII and BP230/dystonin make epitope spreading a plausible route by which neurodegeneration and cutaneous autoimmunity reinforce each other. This neuroinflammatory axis therefore integrates the former cytokine, BBB, microglial, barrier, dysbiosis, and BP autoantigen mechanisms into one measurable pathway (Table 2, Figure 1). Among the three axes, this is the strongest and most biologically coherent pathway: associations noted at the cohort level provide moderate epidemiologic support, the inflammation-BBB-neuroinflammation sequence is broadly accepted, and data emerging from an atopic dermatitis model implicate IL-17 in BBB disruption, neuroinflammation, and cognitive dysfunction (28,30). Nevertheless, these lines of evidence should not be read as direct proof that skin inflammation causes dementia.

Table 2. Three-axis mechanisms linking skin disease and cognitive impairment.

Mechanism	Dermatological examples	Molecular / clinical detail	Potential brain-level consequence	Interpretation
Axis 1: Neuroinflammation	Psoriasis, AD, BP, rosacea, PN/chronic prurigo	Cutaneous IL-1β, IL-6, TNF-α, IL- 17/23, IL-4/13, IL-31, TSLP, and IL- 33 can prime endothelium and BBB vulnerability; BP180/BP230 epitope spreading adds a disease-specific autoimmune bridge.	BBB dysfunction, microglial and astrocytic priming, cytokine amplification, reduced cognitive reserve	Unifies cytokines, BBB, microglia, barrier failure, dysbiosis, and BP autoantigen sharing into one testable pathway (Evidence level: strongest but still indirect).
Axis 2: Neurovascular injury	HZ/VZV reactivation; psoriasis and rosacea endothelial activation	VZV neurotropism, endothelial infection, vasculitis, thrombosis, ischemia, TLR2/NF-κB signaling, NLRP3 inflammasome activation, and amyloidogenic stress.	Vascular cognitive impairment, white-matter injury, delirium, gait decline , dementia acceleration	Most specific preventable bridge; supports vaccination, urgent antivirals , and neurovascular follow-up after complicated HZ (Evidence level: moderate/inferential; direct evidence limited).
Axis 3: Neurofunctional disruption	AD, PN, BP, chronic pruritus/xerosis	IL-31/TSLP sensory circuits, nocturnal itching, scratching, pain, fragmented sleep, sedating or anticholinergic drugs, systemic corticosteroids, infection, and frailty.	Attention and memory fluctuation, sleep-related cognitive burden, delirium vulnerability, functional decline	Most dermatology-specific clinical axis; nocturnal itching and actigraphy can become cognitive-risk indicators (Evidence level: clinically strong but indirect functional pathway).

Abbreviations: BP, bullous pemphigoid; HZ, herpes zoster; CNS, central nervous system; AD, atopic dermatitis; PN, prurigo nodularis; VZV, varicellazoster virus.

Figure 1.

Three-axis skin-brain framework for dermatological control as a dementia-modifying strategy. Aging skin can function as a sentinel organ for neurodegeneration through Axis 1, neuroinflammation (cytokines, BBB vulnerability, microglia, and BP180/BP230-related autoimmunity); Axis 2, neurovascular injury (VZV, endothelial activation, vasculopathy, thrombosis, ischemia, and amyloidogenic stress); and Axis 3, neurofunctional disruption (itching, pain, fragmented sleep, medication toxicity, frailty, and delirium). Dermatology-led interventions--barrier repair, steroid-sparing BP therapy, cognitive screening before corticosteroids, zoster vaccination and antivirals, monitoring of nocturnal itching in AD, actigraphy in PN, sleep optimization, and a medication review--represent practical points at which clinicians can interrupt the pathway. Converging evidence suggests that these axes link cutaneous disease to brain vulnerability, although causality remains to be established. Abbreviations: BP, bullous pemphigoid; HZ, herpes zoster; PN, prurigo nodularis; BBB, blood-brain barrier; VZV, varicellazoster virus.

4.2. Neurovascular injury

The second axis emphasizes vascular injury, with HZ/ VZV reactivation as the clearest dermatological trigger. VZV can infect neural and vascular tissue, activate IL-6 production through TLR2-dependent NF-κB signaling, trigger NLRP3 inflammasome assembly with IL- 1β processing, and create amyloidogenic cellular and plasma environments (44-47). Clinically, ophthalmic or CNS-involved zoster can converge on endothelial inflammation, vasculitis, thrombosis, white-matter ischemic injury, delirium, gait decline, and vascular cognitive impairment. Psoriasis and rosacea may contribute to the same axis through chronic endothelial activation and microvascular dysfunction, but HZ supplies the most specific and preventable neurovascular model (17-21,24-28,38,39). Compared to axis 1, this pathway is supported by strong general evidence that peripheral inflammation can degrade BBB integrity, but direct evidence that cutaneous disease itself causes neurovascular cognitive injury remains limited. The genetic or pathway overlap between psoriasis, AD, Alzheimer's disease, and Parkinson's disease is suggestive rather than definitive, and the vascular-inflammation model is biologically plausible but still largely inferential. For HZ/VZV, the zoster-brain vasculopathy-cognition chain is clinically important but remains based on a handful of clinical observations rather than systematic causal evidence.

4.3. Neurofunctional disruption

The third axis depicts how skin disease degrades brain function even when structural neurodegeneration in not yet evident. Nocturnal itching, pain, burning, dysesthesia, scratching, and anxiety repeatedly fragment sleep, reduce slow-wave sleep, impair daytime attention, and disrupt circadian and autonomic stress responses. In AD and PN, IL-31-, TSLP-, periostin-, and IL-33- linked sensory-neuroimmune loops make itching both a symptom and a quantifiable brain-related mediator. In BP and chronic pruritus, sedating antihistamines, anticholinergics, opioids, systemic corticosteroids, infection, and frailty can compound chronic vulnerability with reversible confusion (15,34,35,48). This axis is especially dermatology-specific because itching intensity, nocturnal scratching, topical feasibility, actigraphy, and sleep response are directly visible and modifiable in skin clinics. The clinical evidence is convincing but mechanistically indirect: skin disease can reliably induce itching, pain, and sleep fragmentation, and sleep disturbance is a well-established contributor to cognitive decline, whereas evidence that this pathway directly causes structural neurodegeneration remains limited. Accordingly, axis 3 is best defined as a functional and behavioral route to cognitive vulnerability rather than a direct neurodegeneration mechanism.

5. Emerging interventional evidence: From dermatology trials to brain-related endpoints

A clearer evidence hierarchy helps preserve scientific caution without weakening the central message (Table 3). The strongest dementia-related signals currently come from zoster vaccine natural experiments and matched cohort analyses, followed by disease-specific epidemiology with biological specificity, mechanistic studies, and dermatology trials that improve brain-related mediators such as itching, sleep, steroid burden, and vascular inflammation. This ladder supports a practical translation: dermatological control should be evaluated not only by with skin clearance but also with delirium, sleep, cognitive fluctuations, gait, caregiver burden, medication toxicity, and biomarker endpoints. With regard to BP, the BLISTER trial showed that doxycycline was safer than prednisolone over 52 weeks as an initial strategy, a clinically meaningful finding for frail older adults at risk of delirium, infection, and steroid myopathy (48). With regard to AD, dupilumab produced rapid and sustained improvement in sleep across five randomized trials (49). With regard toa1 PN, dupilumab and nemolizumab alleviated itching and improved sleep within days to weeks (41,42). Psoriasis provides a useful cautionary note: vascular imaging endpoints in biologic trials have been more difficult to shift than cutaneous scores, indicating that brain-related pathways may need to be observed longer or measured using more specific biomarkers (50) (Table 4).

Table 3. Evidence hierarchy for dermatological control as a dementia-modifying strategy.

Evidence tier	Evidence type	Representative examples	Brain-relevant inference	Dermatology-specific action
1	Quasi-experimental prevention signal	Live, recombinant, and AS01- adjuvanted zoster vaccine analyses	A visible skin-preventive intervention may alter dementia timing or diagnosis-free survival.	Make zoster vaccination review routine in dermatology and geriatric skin visits.
2	Disease-specific epidemiology plus biological specificity	BP with dementia and BP180/BP230 neurocutaneous autoimmunity; complicated HZ with cognitive outcomes	Certain dermatoses behave as sentinel organs for brain vulnerability rather than nonspecific comorbidities.	Use BP and complicated HZ as triggers for cognitive screening, delirium-risk review, and caregiver planning.
3	Mechanistic and experimental support	Cytokine-BBB-microglia signaling; VZV inflammasome and amyloidogenic signaling; endothelial activation	The three axes are biologically testable with inflammatory, vascular, imaging, sleep, and neurocognitive endpoints (The relative confidence differs by axis: Axis 1 is the strongest mechanistic pathway, Axis 2 is plausible but more speculative, and Axis 3 is clinically robust but functionally indirect).	Embed mechanistic sampling and cognitive outcomes into dermatology cohorts and trials.
4	Dermatology RCTs targeting brain-relevant mediators	BLISTER in BP; dupilumab in AD and PN; nemolizumab in PN; vascular imaging trials in psoriasis	Treatments already modify steroid burden, itching, sleep, scratching, or vascular inflammation--the mediators most likely to affect cognition.	Choose therapies with attention to sleep, itching, delirium, medication toxicity, and frailty rather than skin scores alone.
5	Clinic-level sentinel monitoring	Nocturnal itching in AD, actigraphy in PN, steroid decisions in BP, ocular/CNS HZ follow-up	Dermatology can identify risk earlier than memory clinics because the relevant signals are visible, symptomatic, and longitudinal.	Track nocturnal itching, scratching, topical feasibility, caregiver capacity, and medication burden as cognitive-risk indicators.

Abbreviations: BP, bullous pemphigoid; HZ, herpes zoster; CNS, central nervous system; AD, atopic dermatitis; PN, prurigo nodularis; BBB, blood-brain barrier; VZV, varicellazoster virus; RCTs, randomized controlled trials.

Table 4. Interventional and experimental evidence relevant to the skin-brain axis.

Intervention/condition	Design/population	Brain-relevant endpoint	Main results	Interpretation
Live zoster vaccine	Natural experiment in Wales; older adults eligible by birth-date cutoff	Incident dementia over 7 years	Vaccination associated with 20% relative reduction in new dementia diagnoses.	Best current quasi-experimental evidence that a dermatological preventive intervention may alter dementia risk (20).
Recombinant zoster vaccine (Shingrix)	Matched EHR-based natural exper iment compar ing recombinant vs. live vaccine	Time lived without dementia diagnosis	Recombinant vaccine associated with 17% longer diagnosis-free time, equivalent to 164 additional days without dementia diagnosis.	Supports a clinically meaningful vaccine signal and motivates trials focused on mechanism and causality (19).
Doxycycline-first strategy in BP	Pragmatic non-inferiority RCT; 253 analyzable BP patients, mean age 77.7 years	Severe/life-threatening/fatal treatment-related events at 52 weeks	Short-term blister control was lower than prednisolone, but long-term severe adverse events were much lower with doxycycline (18.2% vs 36.3%).	Not a dementia trial, but highly relevant because steroid toxicity and frailty can worsen cognition in older BP patients (48).
Dupilumab in AD	Five randomized, double-blind, placebo-controlled trials, pooled N=2,632	Sleep loss and sleep disturbance	Sleep improved rapidly and durably, with significant separation from placebo beginning in week 1-2.	Provides interventional support for the itching-sleep-cognition pathway (49).
Dupilumab in PN	Two randomized phase 3 trials (PRIME/PRIME2)	Worst itching NRS and skin lesion response	Both trials met primary and key secondary endpoints, with a marked reduction in itching and alleviation of lesions.	Demonstrates that one of the most cognitively burdensome itching disorders is now targetable with modern therapy (41).
Nemolizumab in PN	Phase 2 randomized trial/ post hoc sleep analysis	Sleep disturbance and scratching during sleep	Improvement in sleep disturbance emerged within days; actigraphy showed reduced scratching during sleep.	Particularly relevant to cognitive vulnerability induced by chronic nocturnal arousal (42).
Secukinumab in psoriasis (VIP-S)	Randomized placebo-controlled trial, n = 91	Aortic vascular inflammation by FDG-PET/CT	Cutaneous improvement was achieved, but short-term vascular imaging improvement was neutral.	Important negative/neutral comparator showing that brain-relevant systemic endpoints may not normalize as quickly as skin scores (50).

Abbreviations: BP, bullous pemphigoid; AD, atopic dermatitis; PN, prurigo nodularis.

6. What should clinicians do now?

The key message is practical rather than speculative. Older adults and cognitively impaired patients should receive better care to prevent skin disease and be treated earlier, not only because skin disorders are distressing, but because uncontrolled cutaneous inflammation may contribute to broader neurologic vulnerability. For BP, guideline-concordant anti-inflammatory treatment, itching control, infection prevention, wound care, and steroid stewardship are essential (15). For HZ, vaccination, prompt antiviral treatment, and a closer neurological follow-up after a complicated infection are reasonable low-regret measures (17-23). For psoriasis and AD, clinicians should actively suppress inflammation, restore the barrier, address sleep and mood, simplify regimens, and avoid chronic systemic corticosteroids where modern guideline-supported options exist (27,31-34,49). These actions are summarized in Table 5.

Table 5. Guideline-informed clinical actions at the skin-brain interface.

Condition/setting	Skin-focused action	Cognition-focused action	Guideline/consensus anchor	Key caveat
BP	Use guideline-concordant anti-inflammatory treatment, wound care, infection prevention, itching control, and steroid-sparing strategies; make cognitive status part of the treatment choice before systemic corticosteroids.	Document baseline cognition, delirium risk, falls, sleep disruption, caregiver ability to apply topical therapy, and steroid toxicity risk before starting systemic treatment.	EADV BP guideline	The key dermatology decision is not only which drug controls blisters, but which regimen is least likely to destabilize cognition in a frail patient.
HZ prevention in older adults	Administer 2-dose recombinant zoster vaccine to eligible adults; review vaccination status routinely.	Integrate vaccine review into memory-clinic, geriatric, and dermatology visits.	ACIP/CDC recommendations	Vaccinat ion is not yet a proven dementia-prevention therapy despite encouraging observational data.
Acute HZ	Promptly start antivirals and monitor for ocular or CNS complications.	Watch for delirium, pain-related insomnia, and functional decline after infection.	Population-based cohort evidence plus standard HZ care principles	Neurologic risk appears highest with complicated or CNS-involved disease.
Psoriasis	Suppress systemic inflammation and optimize long-term disease control; assess metabolic and vascular comorbidities.	Screen for depression, sleep problems, vascular risk, and subjective cognitive complaints.	AAD-NPF psoriasis comorbidity guideline	The dementia signal is modest and heterogeneous; avoid overstating causality.
AD	Prioritize moisturization, barrier repair, topical anti-inflammatory therapy, and modern systemic options when indicated; avoid chronic systemic corticosteroids.	Treat nocturnal itching as a cognitive biomarker: track sleep diaries, caregiver reports, nighttime scratching, daytime attention, and regimen complexity.	AAD adult AD guidelines	Cognitive benefit is not yet proven, but itching and sleep are measurable, treatment-responsive mediators that dermatologists can monitor.
Rosacea	Treat by phenotype, suppress papulopustular inflammation, and control flushing/ocular disease using guideline-based therapy.	Ask about subjective cognitive change, migraine-like symptoms, sleep quality, and medication burden in older adults with persistent inflammatory disease.	S2K rosacea guideline	Direct intervention data on cognition are absent; action is currently based on epidemiologic and mechanistic plausibility.
PN/chronic prurigo	Use stepwise chronic-prurigo management and consider modern targeted therapy when disease is severe or sleep-disruptive; quantify scratching burden when possible.	Track nocturnal itching, concentration, mood, caregiver-reported day-night function, and actigraphy-derived scratching/sleep metrics when feasible.	PN guideline/expert guidance	Actigraphy can turn a skin symptom into a cognitive-risk signal and a trial endpoint, but implementation standards are still emerging.
Cross-cutting older adult/dementia care	Perform a routine skin inspection, xerosis care, itching screening, wound surveillance, and medication reconciliation.	Classify patients by the three axes- -neuroinflammation, neurovascular injury, and neurofunctional disruption-- and flag first-generation antihistamines, benzodiazepines, anticholinergics, opioids, and repeated steroid bursts.	WHO dementia risk-reduction guidance and geriatric best practice	Only dermatology routinely observes the visible triggers-- barrier failure, blistering, zoster, itching behavior, scratch injury, and topical feasibility--that make this prevention pathway actionable.

Abbreviations: BP, bullous pemphigoid; HZ, herpes zoster; CNS, central nervous system; AD, atopic dermatitis; PN, prurigo nodularis.

For rosacea and chronic prurigo, clinicians should also think beyond appearance scores. Refractory burning, flushing, facial dysesthesia, or nocturnal pruritus may signal broader neurovascular or neuroimmune dysregulation, warranting explicit assessment of sleep quality, mood, subjective cognitive change, and caregiver burden. Across all older patients, medication reconciliation should specifically flag first-generation antihistamines, benzodiazepines, anticholinergic co-prescriptions, and repeated corticosteroid bursts.

Being mindful of the converse view is important. Patients with mild cognitive impairment or dementia are less able to report itching, adhere to topical regimens, recognize secondary infection, or tolerate burdensome full-body treatment plans. Dermatologists should therefore ask about memory impairment, missed medications, falls, nighttime agitation, and caregiver capacity when evaluating older patients with severe inflammatory dermatoses. Geriatricians and neurologists should add a routine skin inspection, xerosis care, itching screening, and a vaccination review to dementia care. A skin-limited model of care is no longer adequate for this population.

A practical research-ready workflow would include: baseline cognitive screening in older patients with BP, HZ, severe AD, severe psoriasis, rosacea with a substantial inflammatory burden, or chronic prurigo; structured recording of nocturnal itching and sleep loss; and longitudinal tracking of steroid exposure, vaccination status, falls, delirium, and caregiver-reported functional changes. These measures are simple enough for clinical use and could rapidly generate pragmatic data.

7. Conclusion

Healthy skin and healthy cognition should not be siloed. Current evidence does not prove that treating skin disease will prevent dementia, but it does support a biologically coherent and clinically actionable hypothesis: chronic skin inflammation, barrier dysfunction, viral reactivation, and itching-related physiological stress may all feed a skin-brain inflammatory axis. Accordingly, older adults and people with cognitive impairment should receive more proactive dermatological care, while older patients with severe skin disease need to be closely monitored for cognitive decline. An integrated approach is already justified on clinical grounds, and future prospective studies should determine how well it can protect the brain. The next generation of studies should pair dermatological interventions with brain-related endpoints—cognitive trajectory, delirium, actigraphy, endothelial biomarkers, neurofilament light, MRI white-matter burden, and pragmatic vaccination or steroid-sparing trials in older adults. Writings on this topic are most persuasive when they are honest about causality and yet forward-thinking enough to envision where the field should go next.

Funding:

This work was supported by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science, and Technology of Japan (24K14216).

Conflict of Interest

The authors have no conflicts of interest to disclose.