Objective: .

Background: Scans without evidence of dopaminergic deficit (SWEDD) refers to patients clinically diagnosed with Parkinson’s disease (PD), but show normal findings on dopamine transporter single-photon emission computed tomography (DAT-SPECT). This entity remains highly debate but recent findings suggesting that DAT-SPECT does not reflect either nigral cell bodies or striatal fibers of dopaminergic nigrostriatal neurons could improve our understanding of SWEDD phenomenon. Notably, compensatory downregulation of DAT in the early stages of PD seems to be less efficient in older-onset than in young-onset patients.

Method: We report eight patients with old-age PD diagnosis confirmed during a long-term clinical follow-up and with a positive response to levodopa in which baseline DAT-SPECT was normal both visually and semiquantitatively. Two subjects demonstrated an abnormal scan when repeated later.

Results: .

Conclusion: We suggest that old onset PD SWEDD patients may truly have dopaminergic degeneration despite normal imaging results, simply because of the co-occurrence of an age-related failure of striatal compensatory strategies in the early stages of PD.

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