Imaging of dopamine transporters with [123I]FP-CIT SPECT does not suggest a significant effect of age on the symptomatic threshold of disease in Parkinson's disease

Authors

  • Jan Booij,

    Corresponding author
    1. Graduate School of Neurosciences, Department of Nuclear Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
    • Department of Nuclear Medicine, F2N, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
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  • Paul Bergmans,

    1. Graduate School of Neurosciences, Department of Neurology, Academisch Ziekenhuis Vrije Universiteit, Amsterdam, The Netherlands
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  • Ania Winogrodzka,

    1. Graduate School of Neurosciences, Department of Neurology, Academisch Ziekenhuis Vrije Universiteit, Amsterdam, The Netherlands
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  • Johannes D. Speelman,

    1. Department of Neurology, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands
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  • Erik Ch. Wolters

    1. Graduate School of Neurosciences, Department of Neurology, Academisch Ziekenhuis Vrije Universiteit, Amsterdam, The Netherlands
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Abstract

Parkinson's disease (PD) is characterized neuropathologically by degeneration of the nigrostriatal dopaminergic pathway. With natural aging there is loss of dopaminergic cells in the substantia nigra and, consequently, loss of dopamine transporters in the striatum. It has been suggested that PD is caused by an accelerated rate of cell death. Conceptually, symptoms in idiopathic PD become apparent after a critical level of cell loss, the “symptom threshold.” It has been suggested that this symptom threshold is independent of age. In this study, [123I]FP-CIT SPECT was used to assess the effect of aging on the density of striatal dopamine transporters in vivo in controls (n = 36) and early, drug-naïve, patients with PD (n = 32). We found a significant age-associated decline of [123I]FP-CIT binding to striatal dopamine transporters in controls, but not in parkinsonian patients. This finding might give further support for the existence of an age-independent threshold in PD. In a subgroup of patients with hemi-PD, we found a significant loss of dopamine transporters bilaterally in the caudate nucleus and putamen. This loss was more pronounced in the putamen than in the caudate nucleus and the contralateral binding was significantly lower than the ipsilateral binding. By using age-corrected data, we estimated that in our particular patient group motor signs started when the loss of [123I]FP-CIT binding ratios in the putamen was 46–64%. Synapse 39:101–108, 2001. © 2001 Wiley-Liss, Inc.

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