Memory performance associates with serotonin transporter in midbrain and pons in healthy subjects

We aimed to evaluate the association between the availability of serotonin transporter (SERT) measured by ioflupane-DaTSCAN (¹²³I-FP-CIT) and imaged by single photon emission tomography (SPET) and memory function in healthy subjects.

Specific binding of ¹²³I-FP-CIT indicating SERT was achieved using a region of interest analysis. Spherical volumes of interest for midbrain and pons were defined. The cerebellum was chosen as a reference region. Specific binding ratios (SBR) in midbrain and pons representing SERT availability were measured as follows: SBR=(target-cerebellum)/cerebellum. A hundred and eighty-one healthy subjects (117 male, 64 female) were included in this study.

Specific binding ratios of both midbrain (P=0.025) and pons (P=0.006) of males was higher than that of females. None of the SBR showed a correlation with age both in males: (midbrain; P=0.736, pons; P=0.875) and in females (midbrain; P=0.294, pons; P=0.170). In all our cases, SERT availability of midbrain correlated positively with total recall score (rho=0.159, P=0.033), and delayed recall score (rho=0.149, P=0.046). In females, the correlation between SERT availability in midbrain and delayed recall score was significant (rho=0.320, P=0.010), however, not in males (rho=0.112, P=0.229).

In conclusion, we demonstrated that SERT availability was associated with memory function in healthy females from the PPMI database. Further studies are needed to clarify underlying mechanisms of this phenomenon.