(CNN) A single dose of psilocybin, a compound found in "magic mushrooms," provides long-term relief of anxiety and depression in cancer patients, a new study finds.

In fact, cancer patients who were given psilocybin reported reductions in anxiety, depression, hopelessness, demoralization, and death anxiety more than four years after receiving the dose in combination with psychotherapy.

"Our findings strongly suggest that psilocybin therapy is a promising means of improving the emotional, psychological, and spiritual well-being of patients with life-threatening cancer," said Dr. Stephen Ross, associate professor of psychiatry in the Department of Psychiatry at NYU Langone Health.

The findings build on improvements first reported by the team in 2016, in which 29 patients with cancer-related anxiety and depression were given either a single dose of psilocybin or a vitamin placebo called niacin. Seven weeks later, they were given the opposite. This was in combination with nine psychotherapy sessions.

By 6½ months, after all patients had received psilocybin, about 60% to 80% showed clinically significant reductions in depression, anxiety and existential distress and and improved attitudes toward death.

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