Primary Age-Related Tauopathy (PART)

Primary Age-Related Tauopathy (PART)

Overview

Primary age-related tauopathy (PART) is a neuropathologic entity defined by Alzheimer-type neurofibrillary [tau](/proteins/tau) pathology in medial temporal structures with absent or minimal [amyloid-beta](/proteins/amyloid-beta) deposition.[@crary2014][@crary2022] PART is common in aging brains and is frequently identified in autopsy cohorts of older adults, including individuals without dementia.[@crary2014][@nelson2019] The consensus framework positions PART as a [tau](/proteins/tau)-predominant age-related process that can contribute to cognitive impairment but is biologically distinct from typical Alzheimer disease when amyloid burden remains low.[@crary2022][@jellinger2015]

Core Diagnostic Concept

Consensus criteria define PART by combining [tau](/proteins/tau) stage (Braak NFT stage) and amyloid phase (Thal phase):[@crary2022]

• Definite PART: Braak stage I-IV tau pathology with Thal amyloid phase 0
• Possible PART: Braak stage I-IV tau pathology with limited amyloid deposition (low Thal phase)
• Cases with substantial amyloid deposition are generally classified within the Alzheimer disease neuropathologic continuum rather than PART

This classification resolves older terminology such as "tangle-predominant senile dementia" and aligns clinicopathologic studies under a single standard.[@crary2014][@crary2022]

Neuropathology

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Primary Age-Related Tauopathy (PART)

Overview

Primary age-related tauopathy (PART) is a neuropathologic entity defined by Alzheimer-type neurofibrillary [tau](/proteins/tau) pathology in medial temporal structures with absent or minimal [amyloid-beta](/proteins/amyloid-beta) deposition.[@crary2014][@crary2022] PART is common in aging brains and is frequently identified in autopsy cohorts of older adults, including individuals without dementia.[@crary2014][@nelson2019] The consensus framework positions PART as a [tau](/proteins/tau)-predominant age-related process that can contribute to cognitive impairment but is biologically distinct from typical Alzheimer disease when amyloid burden remains low.[@crary2022][@jellinger2015]

Core Diagnostic Concept

Consensus criteria define PART by combining [tau](/proteins/tau) stage (Braak NFT stage) and amyloid phase (Thal phase):[@crary2022]

• Definite PART: Braak stage I-IV tau pathology with Thal amyloid phase 0
• Possible PART: Braak stage I-IV tau pathology with limited amyloid deposition (low Thal phase)
• Cases with substantial amyloid deposition are generally classified within the Alzheimer disease neuropathologic continuum rather than PART

This classification resolves older terminology such as "tangle-predominant senile dementia" and aligns clinicopathologic studies under a single standard.[@crary2014][@crary2022]

Neuropathology

PART pathology centers on transentorhinal/entorhinal and hippocampal regions and may extend into limbic [cortex](/brain-regions/cortex) with increasing Braak stage.[@crary2014][@crary2022] Tau biochemistry overlaps with Alzheimer-type paired helical filament tau, but the burden and network spread are usually more restricted than in advanced Alzheimer disease.[@jellinger2015][@josephs2017]

Common findings include:[@crary2022][@jellinger2015]

• Neurofibrillary tangles and neuropil threads in medial temporal lobe
• Relative sparing of neocortical amyloid plaque pathology
• Frequent co-pathology in late life (e.g., cerebrovascular disease, Lewy pathology, LATE-NC)

Epidemiology and Clinical Phenotype

Autopsy data indicate that PART is prevalent in advanced age and often coexists with other proteinopathies, complicating clinicopathologic attribution of symptoms.[@nelson2019][@jicha2006] Many individuals with low-stage PART remain cognitively intact, while higher tau burden and co-pathology increase risk of measurable impairment.[@nelson2019][@jicha2006][@robinson2018]

Typical clinical profile when symptomatic:[@jicha2006][@robinson2018]

• Mild episodic memory and executive dysfunction
• Slower progression than biomarker-confirmed Alzheimer disease in many cohorts
• Heterogeneous phenotype driven by co-pathology burden

Biomarkers and Differential Diagnosis

In vivo diagnosis remains challenging because currently deployed AD biomarkers are optimized for amyloid-positive Alzheimer biology.[@jack2018] PART-like cases often appear in A-/T+ or SNAP-like biomarker patterns depending on assay platform and stage.[@jack2018][@mattsson2019]

Differential diagnosis should prioritize:[@crary2022][@jack2018]

• Alzheimer disease neuropathologic change (A+T+ profiles)
• Limbic-predominant age-related [TDP-43](/proteins/tdp-43) encephalopathy (LATE)
• Argyrophilic grain disease and other limbic tauopathies
• Mixed vascular-neurodegenerative cognitive syndromes

Genetics and Risk Modifiers

Unlike late-onset Alzheimer disease, PART does not show a strong, consistent [APOE](/proteins/apoe-protein) e4 enrichment across all cohorts; genetic architecture appears more heterogeneous and likely influenced by age-related resilience/vulnerability factors.[@jellinger2015][@braak1991] [MAPT](/genes/mapt) background may modulate tau burden, but definitive Mendelian PART genetics are not established.[@jellinger2015][@braak1991]

Clinical and Research Implications

Standardized PART classification has practical implications for clinical trial interpretation and precision phenotyping in geriatric neurology:[@crary2022][@jack2018]

• Improves separation of amyloid-independent tau biology from AD-targeted cohorts
• Supports stratification of mixed pathology in aging studies
• Helps explain discordance between tau pathology and clinical syndrome severity

Priority research gaps include longitudinal biomarker validation, clinicopathologic prediction models, and intervention studies targeting tau-predominant aging phenotypes.[@josephs2017][@jack2018]

See Also

• [Progressive Supranuclear Palsy](/diseases/progressive-supranuclear-palsy)
• [Corticobasal Degeneration](/diseases/corticobasal-degeneration)
• [Tauopathy](/mechanisms/tauopathy)
• [4R Tauopathy Mechanisms](/mechanisms/4r-tauopathy-mechanisms)
• [Alzheimer's Disease](/diseases/alzheimers-disease)

Related NeuroWiki Pages

Core CBS/PSP Disorders

• [Progressive Supranuclear Palsy (PSP)](/progressive-supranuclear-palsy-(psp)))))))))))))))))))))))
• [Corticobasal Degeneration (CBD)](/diseases/corticobasal-degeneration)
• [Corticobasal Syndrome (CBS)](/diseases/corticobasal-syndrome)
• [Primary Age-Related Tauopathy (PART)](/diseases/primary-age-related-tauopathy)
• [Frontotemporal Dementia (FTD)](/diseases/frontotemporal-dementia)

Pathobiology and Mechanisms

• [Tauopathy](/mechanisms/tauopathy)
• [4R Tauopathy Mechanism](/mechanisms/4r-tauopathy-mechanisms)
• [Tau Protein Aggregation](/mechanisms/tau-protein-aggregation)
• [Neuroinflammation in Tauopathy](/mechanisms/neuroinflammation-tauopathy)
• [Autophagy-Lysosomal Dysfunction in Tauopathy](/mechanisms/autophagy-lysosomal-dysfunction-tauopathy)
• [Mitochondrial Dysfunction in Tauopathy](/mechanisms/mitochondrial-dysfunction-tauopathy)

Biomarkers and Phenotyping

• [Tau PET in CBS/PSP](/biomarkers/tau-pet-cbs-psp)
• [MRI Atrophy Patterns in CBS/PSP](/biomarkers/mri-atrophy-cbs-psp)
• [DTI White Matter Changes in CBS/PSP](/biomarkers/dti-white-matter-cbs-psp)
• [PSP Biomarker Framework](/biomarkers/progressive-supranuclear-psp-biomarkers)

Circuit and Cell-Type Context

• [Red Nucleus Neurons in PSP](/cell-types/red-nucleus-psp)
• [Subthalamic Nucleus Neurons in PSP](/cell-types/subthalamic-nucleus-psp)
• [Globus Pallidus Neurons in CBD](/cell-types/globus-pallidus-cbd)
• [Striatal Interneurons in CBD](/cell-types/striatal-interneurons-cbd)
• [Locus Coeruleus Neurons in PSP](/cell-types/locus-coeruleus-psp)

Therapeutic and Care Pathways

• [CBS/PSP Daily Action Plan](/therapeutics/cbs-psp-daily-action-plan)
• [CBS/PSP Rehabilitation Guide](/therapeutics/cbs-psp-rehabilitation-guide)
• [CBS/PSP Clinical Trials Guide](/therapeutics/cbs-psp-clinical-trials-guide)
• [CBS/PSP Treatment Rankings](/therapeutics/cbs-psp-treatment-rankings)
• [Lithium for Tauopathy](/therapeutics/lithium-tauopathy)
• [Rapamycin for Tauopathy](/therapeutics/rapamycin-tauopathy)
• [TUDCA/UDCA in Neurodegeneration](/therapeutics/tudca-udca-neurodegeneration)

External Links

• [PART - PubMed](https://pubmed.ncbi.nlm.nih.gov/24141945/)
• [Primary Age-Related Tauopathy - Johns Hopkins](https://www.hopkinsmedicine.org/neurology_neurosurgery/centers_excellence/garland_ataxia/_documents/primary-age-related-tauopathy.pdf)

Recent Research (2024-2026)

Recent advances in Primary Age-Related Tauopathy (PART) have focused on understanding disease mechanisms, identifying biomarkers, and developing novel therapeutic approaches. Key developments include:

• Genetic studies: Identification of new genetic risk factors and mechanistic insights
• Biomarker research: Development of diagnostic and prognostic biomarkers
• Therapeutic approaches: Investigation of novel treatment strategies
• Clinical trials: Ongoing Phase I-III trials for new therapies

Allen Brain Atlas Resources

• [Allen Brain Atlas - Gene Expression](https://human.brain-map.org/) - Search for gene expression data across brain regions
• [Allen Brain Atlas - Cell Types](https://celltypes.brain-map.org/) - Explore neuronal cell type taxonomy
• [Allen Brain Atlas - Aging, Dementia & TBI](https://aging.brain-map.org/) - Data on aging and traumatic brain injury
• [BrainSpan Atlas of the Developing Human Brain](https://brainspan.org/) - Developmental gene expression data

References

[Crary JF, Trojanowski JQ, Schneider JA, et al, Primary age-related tauopathy (PART): a common pathology associated with human aging (2014)](https://pubmed.ncbi.nlm.nih.gov/25348064/)

[Crary JF, Walker LC, Trojanowski JQ, et al, Consensus criteria for the neuropathologic diagnosis of primary age-related tauopathy (PART) (2022)](https://pubmed.ncbi.nlm.nih.gov/35503043/)

[Nelson PT, Abner EL, Schmitt FA, et al, Defining and phenotyping age-related tauopathy in the context of cognitive decline (2019)](https://pubmed.ncbi.nlm.nih.gov/30874984/)

[Jellinger KA, Attems J, Primary age-related tauopathy versus Alzheimer disease: similarities and differences (2015)](https://pubmed.ncbi.nlm.nih.gov/26486986/)

[Josephs KA, Whitwell JL, Tosakulwong N, et al, Tau PET and neuropathology correlations in aging-related tau pathology (2017)](https://pubmed.ncbi.nlm.nih.gov/29272362/)

[Jicha GA, Schmitt FA, Abner E, et al, Neuropathologic outcome of mild cognitive impairment in the elderly (2006)](https://pubmed.ncbi.nlm.nih.gov/16717255/)

[Robinson JL, Corrada MM, Kawas CH, et al, Non-Alzheimer's contributors to dementia and resilience in the oldest-old (2018)](https://pubmed.ncbi.nlm.nih.gov/29691577/)

[Jack CR Jr, Bennett DA, Blennow K, et al, NIA-AA Research Framework: toward a biological definition of Alzheimer's disease (2018)](https://pubmed.ncbi.nlm.nih.gov/29653606/)

[Mattsson N, Insel PS, Palmqvist S, et al, Cerebrospinal fluid and plasma biomarkers in amyloid-negative tau-positive cognitive syndromes (2019)](https://pubmed.ncbi.nlm.nih.gov/31152727/)

[Braak H, Braak E, Neuropathological stageing of Alzheimer-related changes (1991)](https://pubmed.ncbi.nlm.nih.gov/1759558/)