Date: 27 Nov 2008

Monoamine transporter availability in Parkinson’s disease patients with or without depression

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Abstract

Purpose

Depression is a common symptom in patients suffering from Parkinson’s disease (PD) and markedly reduces their quality of life. As post-mortem studies have shown, its presence may reflect extensive cell loss in the midbrain and brainstem with imbalances in monoaminergic neurotransmitters. However, in vivo evidence of specific monoaminergic deficits in depressed PD patients is still sparse. Therefore, we studied PD patients with depression (PD+D) and without depression (PD−D) using high-resolution single-photon emission computed tomography (SPECT) and the monoamine transporter marker [123I]FP-CIT.

Methods

A magnetic resonance imaging-based region-of-interest analysis was applied to quantify the specific-to-nondisplaceable [123I]FP-CIT binding coefficient V3″ in the striatum, thalamus and midbrain/brainstem regions.

Results

PD+D patients had significantly lower V3″ compared with PD−D patients in the striatum (p<0.001), thalamus (p=0.002), and midbrain/brainstem (p=0.025). Only PD+D patients without selective serotonin reuptake inhibitor (SSRI) treatment showed lower thalamic and midbrain V3″ than controls (p<0.001, p=0.029). In a small sub-group of SSRI-treated PD+D patients neither thalamic V3″ nor midbrain/brainstem V3″ differed from those in PD−D patients (p=0.168, p=0.201) or controls (p=0.384, p=0.318).

Conclusion

Our data indicate that depression in PD is associated with a more pronounced loss of striatal dopamine transporter availability that is most likely secondary to increased dopaminergic degeneration. In addition, depressed PD patients have a lower availability of midbrain/brainstem monoamine transporters than nondepressed PD patients. These findings provide in vivo evidence in support of the known post-mortem data demonstrating more extensive nerve cell loss in PD with depression and indicate that SPECT imaging can help to identify pathophysiological changes underlying nonmotor symptoms in this common movement disorder.

The results of this study were partly presented at the Amersham Healthcare User Meeting during the 40th Annual Meeting of the German Society of Nuclear Medicine 2002 in Freiburg, Germany, and at the 54th Annual Congress of the Society of Nuclear Medicine 2007 in Washington, DC, USA.