Impaired brain dopamine transporter in chemobrain patients submitted to brain SPECT imaging using the technetium-99m labeled tracer TRODAT-1.

Purpose: "Chemobrain" is a medical secondary effect of cancer chemotherapy treatment characterized by a general decline in cognition affecting visual and verbal memory, attention, complex problem-solving skills, and motor function. Dopamine (DA) central nervous system neurotransmitters serve an important role in cognition, and changes in DA could potentially explain impaired cognition associated with chemotherapy. Therefore, our objective was to assess in vivo dopaminergic dysfunction in the central nervous system (CNS) of a group of female breast cancer survivors with cognitive impairment following chemotherapy.

Methods: Twenty-eight women reporting chemobrain were recruited for this study and compared to 22 healthy reference women. Striatal dopamine transporter (DAT) binding ratio was determined by Tc-TRODAT-1 (a highly selective radiotracer for DAT in the dorsal striatum) single-photon emission computed tomography and a quantitative evaluation was obtained by DatQUANT™ software (GE Healthcare). The DAT binding ratio (BR) in the patient and control groups was compared using the Student's t test, a multivariate analysis of variance (MANOVA) was used to compare age, years of schooling and BR. The relationship between continuous variables, such as cognitive impairment and BR was assessed using Pearson correlation test.

Results: There was a difference in BR between the chemobrain patients and control group. Patients had statistically significant (p < 0.05) lower concentrations of the radiopharmaceutical in the striatum.

Conclusions: We identified a significant dopaminergic decrease in all regions of the dorsal striatum within the patients reporting cognitive dysfunction after chemotherapy. Therefore, our results indicate a possible role of dopamine transporter in the physiopathology of chemobrain, even out of the acute phase of symptoms.