Reduced dopamine transporter binding predicts early transition to Lewy body disease in Japanese patients with idiopathic rapid eye movement sleep behavior disorder.

PURPOSE

We examined dopamine transporter (DAT) binding in Japanese patients with idiopathic rapid eye movement sleep behavior disorder (IRBD) as a biomarker for the development of Lewy body disease (LBD).

METHODS

[I]FP-CIT SPECT (DAT-SPECT) scans of 74 IRBD patients were compared to those from healthy Japanese subjects, and the predictive value for conversion to LBD during a 5-year follow-up was evaluated.

RESULTS

Baseline DAT deficits (Z-score ≤ -2.5) were observed in 25 (33.8%) of the IRBD patients. During follow-up, 25 patients (33.8%) developed LBD [19 Parkinson's disease and 6 dementia with Lewy bodies], with a mean latency of 2.4 ± 1.6 years from imaging. The receiver operating characteristics curve revealed that the Z-score of baseline DAT binding in the striatum of abnormal DAT-SPECT patients who later developed LBD differed from those who remained disease-free. Kaplan-Meier survival analysis showed an increased risk of LBD in patients with a Z-score ≤ -2.5 for DAT binding in the striatum of abnormal DAT-SPECT patients compared to patients with a Z-score > -2.5.

CONCLUSIONS

DAT-SPECT identifies IRBD patients at short-term risk for developing LBD. Decreased DAT binding in the striatum (Z-score ≤ -2.5) predicts development of LBD within 5 years, and may be useful in future disease-prevention trials in IRBD patients.