RETROGRADE MEMORY DEFICITS IN SEVERE CLOSED- HEAD INJURY PATIENTS Giovanni A. Carlesimo 1 , Maurizio Sabbadini 1 , Patrizia Bombardi 2 , Ester Di Porto 2 , Antonella Loasses 1 and Carlo Caltagirone 1, 3 ( 1 I.R.C.C.S. S. Lucia, Roma; 2 Anni Verdi, Roma; 3 Clinica Neurologica, Università di Roma “Tor Vergata”) ABSTRACT A battery of tests evaluating different aspects of retrograde memory (autobiographical, public events, semantic knowledge) was administered to a group of 20 patients who had suffered from a severe closed-head injury (CHI) and who had recovered from the post- traumatic amnesia period and to a group of sex-, age- and education-matched normal controls. Results document a high prevalence of retrograde memory deficits among CHI individuals. The deficit involves both autobiographical and public events memories and extends to early acquired basic and cultural knowledge. The severity of the deficit does not vary according to some kind of temporal gradient or according to a presumed hierarchical or modality organization of the semantic system. However, in the domain of basic knowledge it more severely affects information pertaining to living than nonliving categories of objects. With the exception of a more severe deficit in retrieving autobiographical events occurred in the last year before trauma in a subgroup of patients with focal lesions restricted to the right hemisphere as compared to left lesioned patients, no clear relationship emerges between severity of the retrograde memory deficit and locus of focal cerebral lesions as demonstrated by neuroradiological exams. Key words: memory, head trauma, semantic system INTRODUCTION A memory disorder is likely the most frequent cognitive deficit in persons who have recovered from the acute phase of a severe closed-head injury (CHI) (e.g., Brooks, McKinlay, Simington et al., 1987). The difficulty in storing new information (anterograde amnesia) has been extensively investigated in both clinical (e.g., Russell, 1971) and neuropsychological studies (e.g., Carlesimo, Sabbadini, Loasses et al., 1997; Levin and Goldstein, 1986; for a review, see Levin, 1989). The impairment in recalling autobiographical and public events which occurred before the head trauma and general semantic information acquired early in life (retrograde amnesia) has been far less investigated. Indeed, in the only group study devoted to this topic, Levin, High, Meyers et al. (1985) compared groups of severe CHI patients who were still experiencing the post-traumatic amnesia period, severe CHI patients following resolution of post-traumatic amnesia and age-matched normal controls on a recognition memory task for titles of television programs broadcasted for a single season in a period ranging from 1 to 13 years prior to the head trauma (Squire and Slater, 1978). In this task, post-traumatic amnesia patients obtained the lowest scores and Cortex, (1998) 34, 1-23