Sweet Thresholds in Healthy Volunteers Study

The sweet threshold (concentration of sucrose in water) at which healthy participants can detect a sweet flavour will be recorded.

Inclusion Criteria: . Male and female adults of 18 years old and over; * Participants without a diagnosis of major depressive disorder (MDD) / anxiety disorder; * Participants not taking an antidepressant during the preceding 6 months * Not suffering from significant other mental or physical illness, such as confirmed psychosis, end of life care, or any other condition assessed as significant by the Site Investigator; * Willing and able to comply with all study-related procedures; * Not having COVID 19 or continuing effects of COVID 19 including altered sense of taste; * Understands the study requirements and the treatment procedures and is able to provide written informed consent. Exclusion Criteria: * Taking antidepressant medication currently or during the previous 6 months; * Known or suspected hypersensitivity or intolerance to any taste testing solutions, or any of their excipients; * A history or presence of neurological or confounding psychiatric conditions (such as stroke, traumatic brain injury, epilepsy, space occupying lesions, multiple sclerosis, Parkinson's disease, vascular dementia, transient ischemic attack, or schizophrenia); * Patients with a diagnosis of chronic pain; * Pregnancy or possibility pregnancy, or breastfeeding; * Participants using supplements containing psychoactive herbs (for example St Johns Wort or 5-HTP (5-Hydroxytryptophan, also known as oxitriptan); * Participants regularly using psychoactive stimulants (for example MDMA); * Participants unable or unwilling to comply with study procedures.