HAM-A

The Hamilton Anxiety Rating Scale (HAM-A) is a 14-item clinician-administered questionnaire developed by Max Hamilton in 1959 to measure the severity of anxiety symptoms. Each item is rated on a 0–4 scale (0 = not present, 4 = very severe), yielding total scores from 0 to 56. The scale covers both psychic anxiety (anxious mood, tension, fears, cognitive symptoms, behavior at interview) and somatic anxiety (muscular, sensory, cardiovascular, respiratory, gastrointestinal, genitourinary, autonomic symptoms). The HAM-A is one of the earliest anxiety rating scales and remains widely used in pharmacological trials, including psychedelic research where anxiety is a co-occurring condition or treatment target. It has good interrater reliability and is often used alongside the HAM-D in studies examining both depression and anxiety outcomes.