What Can Skin Reveal About Dementia?

Detecting phosphorylated alpha-synuclein could add biological context when symptoms and pathologies overlap

By
Jessica Allerton
October 16, 2026
5 min

The Pathologist

At a Glance

Category	Detail
Condition	Dementia and neurodegenerative conditions, including Alzheimer’s disease and dementia with Lewy bodies
Key Mechanisms	Skin biopsy can detect cutaneous phosphorylated alpha-synuclein (P-SYN), a biomarker associated with synucleinopathies; studies also report co-occurring P-SYN and abnormal phosphorylated tau 217 (p-tau 217) findings.
Target Population	People evaluated for suspected dementia or neurodegenerative disease, including participants with mild cognitive impairment associated with suspected dementia with Lewy bodies
Care Setting	Clinical diagnostic evaluation and research studies; quantitative skin-biopsy analysis remains under investigation for research use.

Key Highlights

Clinical symptoms can overlap across dementias, and mixed pathologies may contribute to a patient’s presentation.
Skin biopsy testing can identify whether cutaneous P-SYN is detected.
In the Syn-D study, cutaneous P-SYN was detected in participants with mild cognitive impairment associated with suspected dementia with Lewy bodies before they met clinical criteria for dementia.
A six-month DLB study estimated an approximately 52% annualized increase in cutaneous P-SYN from baseline.
Some Syn-D participants had both cutaneous P-SYN and abnormal p-tau 217 findings.

Guideline-Based Recommendations

Diagnosis

Use skin-biopsy P-SYN findings as additional information alongside established clinical assessments and biomarkers; the source does not present this test as a standalone diagnosis.
Consider that P-SYN and p-tau 217 findings may indicate coexisting Lewy body and Alzheimer’s disease-associated pathologies.

Management

The source describes skin biopsy as potentially complementary to blood biomarkers, cerebrospinal fluid testing, and brain imaging.
Quantitative skin-biopsy analysis is investigational and is being studied for research use.

Monitoring & Follow-up

Longitudinal studies reported increasing cutaneous P-SYN levels; further research is needed to clarify the role of quantitative measurements in tracking disease-related changes.
The source identifies evaluation of treatment effects as a potential future research application, not an established clinical use.

Risks

Overlapping symptoms and mixed pathologies can make it difficult to distinguish Alzheimer’s disease from dementia with Lewy bodies and other neurodegenerative conditions.
The source does not provide information about skin-biopsy complications or other procedural risks.

Patient & Prescribing Data

The article discusses people undergoing evaluation for suspected Alzheimer’s disease or other dementias, including study participants with suspected DLB-associated mild cognitive impairment and patients with DLB.

No treatment regimen or prescribing data are provided. The article describes P-SYN skin biopsy as a potential biomarker approach and quantitative analysis as investigational.

Clinical Best Practices

Interpret biomarker findings in the context of clinical assessment because dementia presentations may overlap and mixed pathologies may occur.
Treat skin-biopsy P-SYN and Alzheimer’s disease biomarkers such as p-tau 217 as potentially complementary measures, as described in the article.
Distinguish established detection of P-SYN from investigational quantitative analysis of P-SYN deposition.
Do not infer treatment response or disease progression from quantitative skin-biopsy results outside the research context described.