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The Cadomian orogeny reflects S -directed subduction on the northern margin of Greater Gondwana in Ediacaran – Cambrian time (∼600-500 Ma). It is well known from the eastern seaboard of North America, western and southern Europe, Turkey and Iran but is rarely identified in what was its backarc in N. Africa and Arabia. Here I summarize evidence for the Cadomian across ∼6500 km of Arabia and N. Africa from Oman to Morocco. The beginning of the Cadomian in Afro-Arabia cuts across and overlaps in time with earlier Neoproterozoic orogenies leading to the formation of Greater Gondwana, so emphasis is on rocks <570 Ma. Three Cadomian backarc crustal tracts or segments are identified. The eastern segment (Oman, Persian Gulf, eastern Saudi Arabia) mostly consists of buried transtensional basins with little igneous activity. The central segment was characterized by lower crust magma underplating and strong uplift along a N –S axis (Jordan) accompanied by rifting leading to deposition of thick sediments reminiscent of a passive continental margin, and strong evidence for regional metasomatism (Israel). The Zenifim passive margin is 580–610 Ma, older than our arbitrary 570 Ma limit for identifying the Cadomian but clearly post-dates terminal continental collision to form the East African Orogen and so must be related to Cadomian back-arc rifting. Along with related NE-SW trending dike swarms in NE Egypt and Jordan, the orientation of the Zenifim rifted margin, orthogonal to the Cadomian convergent margin, is another indication of strong Cadomian transtension. In contrast, the western segment (Libya, Algeria, Morocco) experienced abundant igneous activity, with evidence for this found especially far south in Libya. Recognition of the Cadomian orogeny in northern Africa provides a useful first step in breaking out distinct tectonic episodes in the ∼300 m.y. long Pan-African orogeny, at least in the north. Finally, the orthogonal relationship between older N –S orogens in the interior of Greater Gondwana and the E -W Cadomian orogen illustrates how the Neoproterozoic plate mosaic grew by subduction initiation exploiting lithospheric weaknesses along its continental margin. Ten recommendations for future research are also suggested. • The ∼550 Ma Cadomian orogeny in N. Africa and Arabia is reviewed for the first time. • N. Africa-Arabia Cadomian crosscuts older Neoproterozoic structures. • N. Afro-Arabia Cadomian is mostly transtensional basins in E, magmatic rocks in W. • Rifted continental margin offshore Israel suggests Cadomian basins lie further W. • 10 suggestions for research are provided. [ABSTRACT FROM AUTHOR]

Former American football players are at risk for chronic traumatic encephalopathy (CTE) which may have parkinsonism as a clinical feature. Former football players were prospectively assessed for parkinsonism. 120 former professional football players, 58 former college football players, and 60 same-age asymptomatic men without repetitive head impacts, 45–74 years, were studied using the MDS-UPDRS to assess for parkinsonism, and the Timed Up and Go (TUG). Traumatic encephalopathy syndrome (TES), the clinical syndrome of CTE, was adjudicated and includes parkinsonism diagnosis. Fisher's Exact Test compared groups on parkinsonism due to small cell sizes; analysis of covariance or linear regressions controlling for age and body mass index were used otherwise. Twenty-two (12.4%) football players (13.3% professional, 10.3% college) met parkinsonism criteria compared with two (3.3%) in the unexposed group. Parkinsonism was higher in professional (p = 0.037) but not college players (p = 0.16). There were no differences on the MDS-UPDRS Part III total scores. Scores on the individual MDS-UPDRS items were low. TUG times were longer in former professional but not college players compared with unexposed men (13.09 versus 11.35 s, p < 0.01). There were no associations between years of football, age of first exposure, position or level of play on motor outcomes. TES status was not associated with motor outcomes. Parkinsonism rates in this sample of football players was low and highest in the professional football players. The association between football and parkinsonism is inconclusive and depends on factors related to sample selection, comparison groups, and exposure characteristics. • Parkinsonism/motor finding prevalence did not differ in former American football players compared to asymptomatic unexposed men. • Former players did have slowness on the Timed Up and Go (TUG) compared to the asymptomatic unexposed men. • TUG times were slower in former football players with TES-CTE probable compared to those with no TES and TES-CTE possible. [ABSTRACT FROM AUTHOR]