Enlarged substantia nigra hyperechogenicity is potential PD risk marker
MedWire News: Study results have found that in healthy people, there is a strong association between having an enlarged substantia nigra midbrain hyperechogenicity (SN+) and eventually developing Parkinson's disease (PD).
Close to 90% of patients with PD have SN+, and a greater frequency of SN+ had been noted in conditions associated with an increased risk for future PD. However, it had been unclear as to whether its manifestation in healthy people is a predictive factor for developing the disorder.
Daniela Berg (Hertie Institute for Clinical Brain Research, Tübingen, Germany) and colleagues from the Prospective Validation of Risk Factors for the Development of Parkinsonian Syndromes (PRIPS) study initially enrolled 1847 adults aged 50 years or older. At baseline, all participants were free from PD, and transcranial sonography was used to measure the presence of SN+. A total of 1535 participants were available for follow-up (mean follow-up interval=37 months) and were assessed for the presence of PD.
Nearly 17% of participants had SD+ at baseline, Berg and colleagues report in the Archives of Neurology. Eleven participants were diagnosed with PD over the course of the study, of whom 80.0% had SN+, versus 18.3% of those without PD.
The risk ratio (RR) for participants with SD+ at baseline developing PD during the follow-up period versus those who were SD- was 17.37. Therefore, as the authors note, this high RR demonstrated "an association between SN+ and subsequent development of PD in healthy adults," and "makes this ultrasonographic marker a strong candidate for screening to narrow a target risk population."
While only a small percentage (3.1%) of participants developed PD, the authors conclude that this was probably due to the relatively short follow-up period. Nevertheless, as the authors note, this is the first study to determine a link between SN+ and the subsequent development of PD.
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By Stephanie Leveene