This is a controlled study of patients with and without primary premature ejaculation. It is based on near-infrared spectroscopy (NIRS) functional brain imaging to detect and compare changes in brain activity in resting and task states (Simulated Sex) between the two groups of patients.

Inclusion Criteria (primary premature ejaculation subjects):

• patients' age varied from 18 to 45 years；
• patients met the 2014 International Society for Sexual Medicine (ISSM) definition criteria for PPE；
• patients had a stable, heterosexual relationship with a single sexually active female partner for at least 6 months and with at least two sexual intercourses a week and kept stable during the study period;
• Patients with premature ejaculation lasting longer than 6 months；
• patients were identified if their scores were higher than 9 on the Chinese version of Premature Ejaculation Diagnostic Tool (PEDT);
• patients had no history of any previous therapies for PE or had recently stopped the therapies for at least 3 months
• patients had fully informed consent, signed informed consent form

Inclusion Criteria (Non-premature ejaculation subjects):

• Men between the ages of 18-45 years were included according to an age difference of <3 years between each patient and the primary premature ejaculation group, and if more than one volunteer was eligible at the same time, the one with the closest age was selected；
• Patient does not meet the 2014 International Society for Sexual Medicine (ISSM) criteria for defining premature ejaculation；
• patients had a stable, heterosexual relationship with a single sexually active female partner for at least 6 months and with at least two sexual intercourses a week and kept stable during the study period;
• patients had fully informed consent, signed informed consent form；

Exclusion Criteria:

• patients were diagnosed with secondary PE, variable PE, and subjective PE;
• patients were using medications for endocrinological, metabolic, chronic systemic, or psychiatric diseases;
• patients were abusing alcohol or illegal drugs；
• patients were diagnosed with erectile dysfunction (ED) if their scores were <21 on the abridged five-item International Index of Erectile Function (IIEF-5)
• patients were diagnosed with sexual hormone abnormalities, hyperthyroidism, hypothyroidism, Peyronie's disease, prostatitis, urethritis, or urinary tract infection;
• patients with head injuries that prevent them from completing near-infrared light brain function imaging
• Patients with severe schizophrenia, anxiety, depression or other neurological symptoms or poor compliance