“…This proportion fluctuates from country to country depending on the the language (written or verbal), the educational system, and the social and cultural conditions (Waltzer and Richmond, i973,MinskofT, ig83,Tarnopol&Tarnopol, i976,Vellutino, 1981). Frequently but not always learning difficulties coexist with hyperkinesis, lack of concentration, behaviour disorder and or soft neurological signs (Cantwell, 1977 hyperactivity, the delay in language development, the behaviour disorder or the environment (Rutter & Yule, 1975;Schachar, Rutter & Smith, 1981;Shaffer et al, 1979;Sturge, 1982;Gillberg et al, 1982;McGee et al, 1984;Jorm et al, 1986). However, the results of the different studies are rather contradictory.…”