Striatal dopamine transporter levels correlate with apathy in neurodegenerative diseases: A SPECT study with partial volume effect correction

Objectives The aim of the present study was to stress the relationship between neuropsychiatric symptoms and most particularly apathy and striatal dopamine uptake in patients with Alzheimerʹs disease (AD) or dementia with Lewy body (DLB). Patients and methods Twenty-two patients (AD n = 14; DLB n = 8) were included. All patients had neuropsychological and behavioral examination including Mini Mental Test Examination (MMSE), Neuropsychiatric Inventory (NPI), and UPDRS for the motor activity assessment. Apathy dimensions, emotional blunting, lack of initiative and lack of interest were assessed using the Apathy Inventory (AI). Dopamine transporter (DAT) striatal uptake was assessed using 123I-FP-CIT (DaTSCAN®) SPECT. Quantitative measurements were obtained in 3D using a method which compensates for physical detection biases including partial volume effect. Results We observed a correlation between DAT uptake and NPIʹs domains only for apathy. More specifically using the AI, lack of initiative significantly correlated with bilateral putamen DAT uptake. Using partial correlation coefficients controlling for the UPDRS score, the correlation remained significant between lack of initiative and right and left putamen DAT uptake. Conclusion These results demonstrate a relationship between apathy and DAT levels independent from motor activity. They suggest that the patients with neurodegenerative diseases presenting with apathy are characterized by some degree of dopaminergic neuronal loss.