18F-fallypride PET-CT of dopamine D2/D3 receptors in patients with sporadic amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a progressive and fatal neurodegenerative disease with unclear pathogenesis. To date, there have been no reports regarding the distribution of dopamine receptors outside the striatum in ALS patients. In this study, 17 ALS patients and 11 healthy controls underwent 18F-fallypride positron emission tomography/computed tomography (PET/CT) and completed cognitive-related tests for assessment of the distribution of dopamine receptors inside and outside the striatum in ALS and evaluation of the relationships between the distribution of dopamine receptors and cognitive function. The results showed that ALS patients showed significantly lower scores only in language and delayed recall of Montreal Cognitive Assessment scale. There were no significant differences between the two groups in the cognitive-related test results. Statistical parametric mapping (SPM) data showed that the binding affinity of 18F-fallypride in ALS patients was decreased in the bilateral nucleus accumbens septi, bilateral frontal lobes, and the superior frontal gyrus, left temporal lobe, and angular gyrus regions. In conclusion, the levels of dopamine receptors were significantly decreased in some areas outside the striatum in patients with ALS, which may contribute to mild cognitive impairment in ALS patients.