Harmaline is thought to act primarily on neurons in the inferior olive. Olivocerebellar neurons exhibit rhythmic excitatory action when harmaline is applied locally.Harmane or harmaline has been implicated not only in essential tremors, but is also found in greater quantities in the brain fluid of people with Parkinsons disease as well as cancer. Higher levels of the neurotoxin are associated with greater severity of the tremors. Harmane is particularly abundant in meats, and certain cooking practices (e.g., long cooking times) increase its concentration, however, at least one study has shown that harmane blood concentrations do not go up after meat consumption in ET patients with already elevated harmane levels, where as the control groups harmane levels increase accordingly, suggesting that another factor, like a metabolic defect, may be responsible for the higher harmane levels in E.T. patients.Caprylic acid is being researched as a possible treatment for essential tremor. It has currently been approved by the FDA and designated as GRAS, and is used as a food additive and has been studied as part of a ketogenic diet for treatment of epilepsy in children. Research on caprylic acid as a possible treatment for ET begun because researchers recognized that ethanol was effective in reducing tremor, and because of this, they looked into longer-chain alcohols reducing tremor. They discovered that 1-octanol reduced tremor and did not have the negative side effects of ethanol.
ET is generally progressive in most cases (sometimes rapidly, sometimes very slowly), and can be disabling in severe cases. Epidemiology
ET is one of the most common neurological diseases, with a prevalence around 4% in persons age 40 and older and considerably higher among persons in their 60s, 70s, and 80s, with an estimated 20% of individuals in their 90s and over. Aside from enhanced physiological tremor, it is the most common type of tremor and one of the most commonly observed movement disorders. Society and culture
Actress Katharine Hepburn (1907–2003) had an essential tremor, possibly inherited from her grandfather, that caused her head—and sometimes her hands—to shake. The tremor was noticeable by the time of her performance in the 1979 film The Corn Is Green, when critics mentioned the "palsy that kept her head trembling". Hepburns tremor worsened in her later life.Charles M. Schulz, American cartoonist and creator of the Peanuts comic strip, was affected during the last two decades of his life. West Virginia Senator Robert Byrd also had essential tremor. In 2010, musician Daryl Dragon of The Captain and Tennille was diagnosed with essential tremor, with the condition becoming so severe that Dragon was no longer able to play the keyboards.Director-writer-producer-comedian Adam McKay was diagnosed with essential tremor.Downton Abbey creator Julian Fellowes has the condition, as does the shows character Charlie Carson.In 2022, Matthew Caws of Nada Surf and his son made a PSA called "Living with a Mild Essential Tremor". Research
Harmaline is a widely used model of essential tremor (ET) in rodents.