The debilitating and fatal neurological Parkinson's disease affects various ethnic groups differently, according to new research at the Rabin Medical Center-Beilinson Campus in Petah Tikva. They have found that Yemenite Jews with Parkinson's suffer more than Jews of Ashkenazi origin who contract it. Chewing the leaves of the khat plant, which is common among Yemenites, may be a factor, they suggest. Parkinson's is a degenerative movement disorder of the brain that often impairs motor skills, speech and other functions. Lead researcher Prof. Ruth Jeladti, who studied the degenerative neurological disease, found that those of Yemenite origin who get Parkinson's show the first symptoms at a younger age on average (55 years) than Ashkenazi Jews (62). The disease also develops faster and the symptoms are more severe among them than in Jews of Ashkenazi origin. There are a higher rate of depression and more cognitive deficits among victims of Yemenite parentage. However, the Clalit Health Services expert said that the first symptoms - tremor, slowness and rigidity of limbs - is the same in those both of Yemenite and Ashkenazi origin. Her team had gotten the impression from their work that the disease was different in the two groups, so they conducted a study on 98 Parkinson's patients of Ashkenazi and 63 of Yemenite origin during the years 2000 to 2008. The progress of their disease until death took an average of eight to nine years. Jeladti said that the finding that Yemenites tend to develop Parkinson's at a younger age was surprising, as 35% of the Ashkenazim had a family history for it compared to only 22% of Yemenites, she said. "When there is a family history, we usually expect that a disease will appear at a younger age." Jeladti said her team had not yet investigated the cause of the ethnic differences, whether it was a gene unique to Parkinson's that has not yet been identified. She suggested that the fact that many Jews of Yemenite origin chew the leaves of the khat plant for its psychedelic properties (even though the chemical inside was recently recognized as an illegal drug) could be a cause of the differences. The psychoactive ingredients in khat have not yet been researched.