Objective: To reveal dopamine transporter (DAT) abnormalities in pure autonomic failure (PAF) and speculate about the relationship with the Lewy body progression pathway.   

Background: Whether PAF is a prodromal state of PD and DLB is not clear. However, understanding the DAT function in PAF will help elucidate why the majority of patients with PAF experience only autonomic dysfunction and seldom progress to motor dysfunction and dementia.

Methods: We performed DAT SPECT and other clinical examinations in patients with PAF. Semi-quantification of FP-CIT accumulation in each part of the striatum in PAF was compared with normal controls (NCs) and patients with PD or DLB.The data were analyzed and compared with the literature.

Results: The subjects were four patients with PAF (3 males, 1female). Orthostatic hypotension, constipation, and hypohidrosis were observed in the absence of parkinsonism. Olfactory dysfunction was observed but was milder than that seen in PD. Also, RBD was one of the cardinal symptoms. FP-CIT accumulation in the four patients with PAF was visually abnormal including marginal irregularity. Semi-quantification of FP-CIT accumulation in each part of the striatum in the patients with PAF showed lower accumulation than in NCs, but higher accumulation than in PD and DLB.

When comparing our data with data from other studies, DAT SPECT findings in the patients with PAF were slightly abnormal to normal. Tijero et al. reported that normal DAT SPECT findings in an initial study turned out to be abnormal at a later time. PAF is a Lewy body disease. Some patients with PAF develop PD or DLB after long-term observation. However, whether PAF is an distinct disorder or a prodromal state of other Lewy body diseases is not clear. Motor dysfunction is observed in PD when more than 50% of dopaminergic neurons are lost. Slight dopaminergic neuronal dysfunction in PAF may precede the onset of motor dysfunction. Some factors that suppresses progression to motor dysfunction may exist in PAF. Interestingly, olfactory dysfunction was observed in PAF but was milder than that in PD. This may indicate that PAF has a disease progression pathway that is distinct from Braak staging.

Conclusions: Slight striatal DAT abnormalities were observed in most patients with PAF in the absence of motor dysfunction. We speculate that PAF has a disease progression pathway that is distinct from Braak staging. 

References: Tijero B, Gómez-Esteban JC, Berganzo K, Zarranz JJ.

REM sleep behaviour disorder and “pure” autonomic failure. Presentation of two cases  Neurologia.2012 Jan;27(1):55-7

« Back to 2017 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/striatal-dopamine-transporter-abnormalities-in-pure-autonomic-failure-and-speculation-about-the-relationship-with-lewy-bodies/