Loudness dependence of auditory evoked potentials (LDAEP) correlates with the availability of dopamine transporters and serotonin transporters in healthy volunteers - A two isotopes SPECT study

Rationale and objective: Although loudness dependence of auditory evoked potentials (LDAEPs) had been suggested as a noninvasive measure of central serotonin functions, recent studies suggest that LDAEP may be modulated by multiple neuromodulatory systems, such as dopamine. Here, we explore the relationship between LDAEP and dopamine and serotonin in the level of monoamine transporter availability. Methods: Forty-nine healthy volunteers received LDAEP and single-photon emission computed tomography (SPECT) using [^99mTc] TRODAT and [¹²³I] ADAM to approximate the availability of dopamine transporters (DATs) and serotonin transporters (SERTs). Results: LDAEP was found to be positively associated with DAT, after adjusting for age and gender, and the log-transformed slope of loudness dependence at Cz was negatively associated with SERT. Conclusion: Our findings provide further evidence for the possible involvement of dopamine and serotonins in the genesis of LDAEP.