Elevation of blood beta-carboline alkaloids in essential tremor.

BACKGROUND

beta-Carboline alkaloids are normal body constituents but are also potent tremor-producing chemicals that are naturally present in the food chain.

OBJECTIVE

To explore the hypothesis that high concentrations of beta-carboline alkaloids are associated with essential tremor (ET).

METHODS

One hundred cases and 100 controls were frequency matched on age, sex, and ethnicity. Blood concentrations of harmane and harmine were quantified by high-performance liquid chromatography, blinded to clinical information.

RESULTS

The mean log blood concentration of harmane was higher in cases than controls (0.72 +/- 0.53 vs 0.51 +/- 0.64 g(-10)/mL; p = 0.01). A nonparametric test on nontransformed data (median harmane = 5.21 g(-10)/mL in cases and 2.28 g(-10)/mL in controls) confirmed this difference (p = 0.005). The mean log blood concentration of harmine was 0.20 +/- 0.48 g(-10)/mL in cases and 0.10 +/- 0.65 g (-10)/mL in controls (p = 0.20). Log harmane concentrations were stratified based on the median value; 62% of cases vs 39% of controls had a high log harmane concentration (p = 0.001). Mean log harmane concentration was similar in the cases with (0.74 +/- 0.58 g(-10)/mL) and without (0.71 +/- 0.50 g(-10)/mL) an affected relative (p = 0.83).

CONCLUSIONS

Blood concentrations of harmane were measured in ET cases compared with controls. Concentrations were elevated in cases with and without a family history of ET.