Introduction: Apathy is a common neuropsychiatric symptom in patients with Alzheimer's disease (AD). The striatal binding potential (BP) of 123 I-FP-CIT ( N -δ-fluoropropyl-2β-carbomethoxy-3β-[4-iodophenyl]tropane) single-photon emission computed tomography (SPECT) is correlated with the degree of apathy in patients with Parkinson's disease (PD) and dementia with Lewy bodies (DLB). This study aimed to determine if dopaminergic activity in the basal ganglia is associated with the development of apathy in AD., Methods: Nineteen subjects with AD were included and underwent 123 I-FP-CIT-SPECT. Patients with other types of dementia as a comorbidity, those taking antidepressants, and those with overt parkinsonism were excluded. Apathy was assessed using the Apathy Evaluation Scale Informant-Japanese version (AES-I-J). SPECT images were overlaid with images in striatal regions of interest (ROIs), and the SPECT values in these regions were counted. The relationship between BP values and AES-I-J scores was investigated using Spearman's rank correlation coefficient., Results: Significant inverse correlations were observed between BP values and AES-I-J scores in the left caudate nucleus and there was a marginally significant inverse correlation in the right caudate nucleus., Conclusion: The pathological basis of apathy might be the impairment of the dopaminergic nervous system. Further studies on more subjects with AD, healthy controls, and patients with PD and DLB are needed., Competing Interests: The authors report no financial or other relationship that is relevant to the subject of this article. N.U. received honoraria from Japan Medi-Physics and Tanabe Mitsubishi Pharma. N.H. received honoraria from Janssen Pharmaceutica, Yoshitomi Yakuhin, Otsuka Pharmaceutical Co., Ltd., Dainippon Sumitomo Pharma, Novartis Pharma, and Meiji Seika Pharma. T.I. received honoraria from Dainippon Sumitomo Pharma and Otsuka Pharmaceutical. H.N. received honoraria from Astellas, Dainippon Sumitomo Pharma, Meiji Seika Pharma, and Otsuka Pharmaceutical. T.S. received research funding from Eisai, Hitachi, Philips Japan, Nihon Medi-Physics, and Fuji RI Pharma. S.N. received honoraria from Otsuka Pharmaceutical, Meiji Seika Pharma, Sumitomo Dainippon Pharma, Kyowa Pharmaceutical Industry, Shionogi, Mitsubishi Tanabe Pharma, Mochida Pharmaceutical, Eisai, Tsumura, Eli Lilly, MSD, and Pfizer, and research/grant support from Otsuka Pharmaceutical, Shionogi, Mitsubishi Tanabe Pharma, Mochida Pharmaceutical, Eisai, Tsumura, Astellas, Eli Lilly, MSD, and Pfizer. I.K. received honoraria from Astellas, Daiichi Sankyo, Dainippon Sumitomo Pharma, Eisai, Eli Lilly, Janssen Pharmaceutica, Kyowa Hakko Kirin, Lundbeck, Meiji Seika Pharma, MSD, Mylan, Novartis Pharma, Ono Pharmaceutical, Otsuka Pharmaceutical, Pfizer, Shionogi, Shire, Taisho Toyama Pharmaceutical, Takeda Pharmaceutical, Tanabe Mitsubishi Pharma, Tsumura, and Yoshitomi Yakuhin, and research/grant support from Astellas, Daiichi Sankyo, Dainippon Sumitomo Pharma, Eisai, Eli Lilly, Kyowa Hakko Kirin, Mochida Pharmaceutical, MSD, Novartis Pharma, Otsuka Pharmaceutical, Pfizer, Shionogi, and Takeda Pharmaceutical, and is a member of the advisory board of Dainippon Sumitomo Pharma., (Copyright © 2020 by S. Karger AG, Basel.)