Different phenoconversion pathways in pure autonomic failure with versus without Lewy bodies

Area of Science:

• Neurology
• Autonomic Neuroscience
• Neurodegeneration

Background:

• Pure autonomic failure (PAF) is characterized by chronic neurogenic orthostatic hypotension (nOH).
• Previous studies suggest PAF can progress to synucleinopathies like Parkinson disease (PD), dementia with Lewy bodies (DLB), or multiple system atrophy (MSA).
• Current clinical classification of PAF may group distinct underlying pathologies.

Purpose of the Study:

• To differentiate subtypes of PAF based on underlying pathology.
• To clarify the phenoconversion potential of distinct PAF subtypes.
• To improve diagnostic accuracy and prognostic prediction for nOH syndromes.

Main Methods:

• Clinical classification of PAF based on nOH without secondary causes or central neurodegeneration.
• Pathological and neurochemical analysis differentiating alpha-synuclein aggregates (Lewy bodies) from their absence.
• Longitudinal clinical and postmortem data analysis.

Main Results:

• PAF with intraneuronal alpha-synuclein aggregates and sympathetic noradrenergic deficiency can phenoconvert to PD or DLB.
• PAF lacking these specific pathological features does not phenoconvert to PD or DLB.
• PAF without alpha-synucleinopathy may represent a premotor form of MSA.

Conclusions:

• Distinguishing PAF subtypes based on alpha-synuclein pathology is critical.
• Phenoconversion pathways differ significantly between PAF subtypes.
• Accurate classification of nOH syndromes improves understanding of neurodegenerative disease progression.