Implicit memory in patien schizophrenia.

Transcription

1 Implicit memory in patien schizophrenia. María José Soler* Jua Inmaculada Fuentes* and Pilar To *Faculty of Psychology. University of Valen C.R.I.S. Velluters. Department of Social Welfare Government of Valencia (Spain). Eulen Co VII International Symposium on Schizophrenia, Ber

2 INTRODUCTION. Schizophrenia is associated with significa cognitive functioning. Deficits in attention, ex and memory have been reported during the las The evidence of memory impairment in ch patients is well documented (McKenna, et al., 2 et al., 1999; MATRICS research group, 2004) focused only in a form of memory that traditionally investigated (e.g. recall and reco working memory). This form of memory is calle

3 However, in recent years, neuropsycholo schizophrenia has paid attention to implicit m investigate whether nonconscious forms of m or preserved in these patients. According to defining feature of an implicit memory t instructions: subjects are told to respond to reference to past experience. Implicit memory has been studied using the phenomenon called priming (Graf & Schac Roediger (1990) defined priming as the experience on tasks that do not require consc recent experiences for their performance.

4 Table 1: Some Implicit tests used nonconscious memory Perceptual tests Conceptual tests word fragment category-instance completion (exemplar) generation lexical decision fact (general knowledge) generation

5 Phases in explicit and implicit t A typical explicit memory test: 1) Subjects are instructed to study some material. (e.g. a list of words). 2) Subjects are told to consciously remember the study episode. (e.g. recall the list of words) In explicit tests, subjects are aware that they are performing a memory task. A typical implic Subjects hav stimulus (called (e.g. to judge th of words). Subjects are to without referen of the test. (e.g. to comple In implicit tests, s the purpose of th causal role of thes

6 Research on implicit memory with schizophren perceptual, procedural and conceptual tests almost all the studies have found it to b performance in schizophrenics was poorer th normal controls. However, in other clinical p has also shown that there are dissociation memory tests (e.g. Beato & Fernandez, 1 patients), suggesting that implicit memory is no Because there are few studies of thes schizophrenics, the aim of this study is to char memory profile of these patients, compar performance and normal controls performan

7 tests: Word fragment completion and Wo semantic categories. Word fragment is a prototypical perceptual te processing of mostly perceptual characteris while, Word production from semantic categor conceptual test that is more demanding with and requires more conceptually elaborated pr expected an impaired performance of schizo conceptual-driven tests, but not on perceptual-d

8 MATERIAL AND METHOD Twenty-nine schizophrenic patients (26 males a included in this study. The diagnosis of schizo according to the DSM-IV criteria. The mean ag 37.9 years. The mean number of years of full Thirty-four normal comparison subjects w comparison on the Word fragment completion normal comparison subjects where used in th

9 from semantic categories test. Subjects in the matched for age and education to the schizoph Participants were administered two implicit Word fragment completion test and the Wo semantic categories test. For the Word fragment completion test, 56 w selected from the Dasí et al. norms (2004). The had a moderate difficulty level of completion (m The variable of interest, the priming score substracting the proportion of studied word completed from the proportion of non-studie correctly completed.

10 Phases in the word fragment complet - first: subjects were required to judge the familia scale ranging from extremely unfamiliar (1) to extre rating sheet, to ensure that participants attended to - second (filler task for five minutes): subjects Spanish cities. - third: participants were asked to complete 56 w Word fragments were presented for 12s each, in missing letters replaced by underscores. Subjects had that came to mind that successfully completed the reference was made to the rated list. 28 of the wo completed with words from the rated list (studied wo remaining 28 word fragments could be completed frequency-matched with the words on the rated fragments).

11 Phases in the word production - first: subjects were required to judge the familia scale ranging from extremely unfamiliar (1) to extre rating sheet, to ensure that participants attended to - second (filler task for five minutes): subjects Spanish cities. - third: participants were asked to give as m possible from 40 semantic categories. 28 categories were represented by an exemplar i category), and the other 12 were completely new in category). Subjects were simply instructed to write as each category as possible in 12s. No explicit reference list.

12 For the Word production from semantic c exemplars with a low probability of generatio were extracted from 40 semantic categories se & Musitu (1980). In this test the priming sco substracting the proportion of expected exemp old categories from the proportion of ex produced from new categories.

13 RESULTS Results were analysed with SPSS (v.11) using (ANOVA). Word fragment completion Test (see table 2) Significantly more studied word fragments compared to non-studied word fragments in [F(1,61) = , p=0.001], and in the contr , p=0.001].

14 Priming obtained in schizophrenic patients (m priming obtained in normal controls (mea statistically identical [F(1,61) = 0.51, p=0.48]. Word production from semantic categories test Significantly more exemplars from old catego compared to exemplars from new categories in [F(1,66) = 2.96, p=0.001], and in the contro , p=0.001]. Priming obtained in schizophrenic patients (m significantly lower than the priming obtained (mean = 0.157).

15 Table 2. Mean proportion and standard deviation (SD) of fragm studied and non studied fragments and priming scores by gr completion test. Studied word fragments Schizophrenics (0.20) (0.13) Controls (0.09) (0.11) Non-studied word fragments Word fragment completion Correct completions 0,7 0,6 0,5 0,4 0,3 0,2 0,1 0 Studied word fragments Condition Non-studied word fragm

16 Table 3. Mean proportion and standard deviation (SD) of expected e and new categories and priming scores by group in the Word categories test. Exemplars from old categories Schizophrenics (0.08) (0.03) Controls (0.10) (0.08) 0,25 0,20 0,15 0,10 0,05 Exemplars from new categories Word production test 0,00 Exemplars from old categories Condition Exemplars from new categories

17 DISCUSSION Results of this study confirm that patients with a global performance significantly worse than implicit memory tests. The mean proportion of correct responses in was lower in schizophrenics than in normal par However, the level of priming obtained in p controls is different, depending on implicit mem On the Word fragment completion test, no stat priming are found between patients and norm size: d=0.18).

18 On the Word production test, priming is sig normal subjects than in schizophrenics (Effect s This dissociation between implicit memory test for by postulating a continuum of tests, from th perceptual information (data-driven tests) knowledge of meaning (conceptually-driven tes In summary, the findings of our study are of pa in the characterization of memory dysfunction i they could help to advance our unde neuropsychology of schizophrenic patients.

19 REFERENCES Aleman A, Hijman R, de Haan EHF, Kahn RS. Memory impaiment in sc American Journal of Psychiatry 1999; 156: Beato MS, Fernandez A. Memoria explícita e implícita en pacientes depre perceptivas y conceptuales. Cognitiva 1995; 7; Dasi C, Soler MJ, Ruiz JC. Normative data on the familiarity and difficulty Behavior Research Methods, Instruments & Computers 2004; 36: Graf P, Schacter D. Implicit and explicit memory for new associations in Journal of Experimental Psychology: Learning, Memory, and Cognition 19 MATRICS. Green MF, Nuechterlein KH. The MATRICS initiative: developin for clinical trials. Schizophrenia Research 2004; 72: 1-3. McKenna PJ, McKay AP, Laws K. Memory in functional psychosis. In: B Memory Disorders in Clinical Practice. Cambridge: Cambridge University P McKenna, PJ, Ornstein T, Baddeley AD. Schizophrenia. In: Baddeley AD, Ko The Handbook of Memory Disorders West Sussex: John Wiley & Sons, Lt Pascual JP, Musitu G. Normas categoriales. Psicológica 1980; 1: Roediger HL. Implicit Memory. Retention without remembering. American Ps Toth JP. Nonconscious forms of human memory. In: Tulving E, Craik FIM, e Memory. Oxford, UK: Oxford University Press, 2000.