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Association Learning in the Acute Confusional State J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.65.3.390 on 1 September 1998. Downloaded from 390 J Neurol Neurosurg Psychiatry 1998;65:390–392 SHORT REPORT Association learning in the acute confusional state Radek Ptak, Klemens Gutbrod, Armin Schnider Abstract and global disturbance of attention in these The usefulness of cognitive rehabilitative conditions.1 Patients in acute confusional state treatment in the acute stages after brain fail to focus on relevant stimuli, react slowly, injury seems questionable because pa- and fail to sustain their attention in tients in severe acute confusional state conversation.2 Alertness and the sleep-wake early after coma clinically seem unable to cycle are usually disturbed, resulting in leth- learn and store new information. There- argy or agitation.3 Some features of the acute fore, the capability of patients in acute confusional state—for example, disorientation, confusional state to learn and retain asso- hallucinations, language, and thought ciative information was assessed. On two disorders—may sometimes be secondary to occasions pairs of simple nouns were pre- attentional diYculties.4 sented to six patients in severe acute con- Clinical evidence suggests that patients in fusional state. Stimuli were presented acute confusional state fail to store ongoing repeatedly either in written form only or events and that after resolution of the acute with additional pictorial representations. confusional state only “islands of memory” Immediate and 20 minutes delayed recall remain.5 However, a systematic investigation of was measured. Patients in acute confu- explicit memory capabilities of patients with sional state were able to learn progres- head injury in severe acute confusional state sively more word pairs across several has never been done. presentations. They retained some infor- Despite this lack of knowledge and the very mation over an interval of 20 minutes. In severe memory disturbance of acutely con- addition, they learned and remembered fused patients, there has been growing demand pictorially supported associations better to start rehabilitative treatment early in the than pure verbal associations. Patients in course of illness.6 However, the ability to severe acute confusional state may retain acquire declarative knowledge is important for some explicit information and may profit rehabilitative eVorts and may even enhance or from an imagery mnemonic aid. These facilitate procedural learning. results were not expected on the basis of The present study investigated declarative clinical findings alone and they have memory in severe acute confusional state. The http://jnnp.bmj.com/ potential implications for the care of goals of this study were to test whether patients patients in acute confusional state. in acute confusional state are able to retain (J Neurol Neurosurg Psychiatry 1998;65:390–392) simple associations after several presentations of the material and whether they benefit from a Keywords: confusional state; traumatic brain injury; visual mnemonic. post-traumatic amnesia Division of Subjects and methods Neuropsychological on October 2, 2021 by guest. Protected copyright. Rehabilitation, The acute confusional state is a common con- Patients in severe acute confusional state, Department of sequence of head trauma, stroke, infections, or several of them just gaining consciousness after Neurology, University other diseases of the brain, and reflects severe coma, were selected. Waxing and waning of Hospital, Bern, Switzerland Table 1 Demographic and clinical characteristics of the patients with acute confusional state R Ptak K Gutbrod Time after A Schnider Education injury Orientation Age Sex (y) (days) Aetiology Initial CT findings score* Correspondence to: 27 f 12 40 TBI Bilateral frontotemporal, right 11 Dr Radek Ptak, Division of medial temporal, and thalamic Neuropsychological contusion Rehabilitation, Department 27 m 13 14 TBI Right medial temporal contusion 10 of Neurology, University 19 m 13 5 TBI Right anterior medial temporal 13 Hospital, CH-3010 Bern, lobe, basal ganglia, and basal Switzerland. Telephone 0041 forebrain contusion 31 6324729; fax 0041 31 35 f 17 44 TBI Left frontotemporal contusion 8 6329770. 32 f 11 21 TBI Left parietotemporal contusion 14 55 m 16 25 Aneurysm rupture (right A Subarachnoidal haemorrhage in 13 Received 3 November 1997 cerebri media) right sylvian fissure and in revised form 16 February 1998 TBI=traumatic brain injury. Accepted 24 February 1998 *A score <15 indicates disorientation.14 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.65.3.390 on 1 September 1998. Downloaded from Association learning in the acute confusional state 391 attention was mandatory for the diagnosis. Day 1 Day 2 Patients showed marked disturbances in con- sciousness and attention, diurnal fluctuations, 4 and disorientation. Reduced vigilance, drowsi- ness, and lethargy were common features of all patients even during the short phases of relative 3 wakefulness. Consensus of three independent clinicians on the diagnosis of acute confusional 2 state was required to include patients. In- formed consent was obtained from the caregivers of all subjects. From 11 patients, five 1 were unable to complete experimental sessions due to their impaired arousal. The table Correctly recalled words (n) presents demographic characteristics of the six 0 Trial 1 Trial 5 Delayed Trial 1 Trial 5 Delayed patients included in the study. recall recall For the severe attentional failure of our Mean performance of patients in acute confusional state patients, two simple associate learning para- learning associations between simple nouns, which were digms were used. Sixteen concrete and image- presented either in written form only (solid line) or with able words were used to prepare two lists of additional pictorial representation (dashed line). Error bars four semantically unrelated word pairs. This show SEM. limited number of items was considered to be by the significant interaction of condition×trial relevant because patients may lose motivation ( (2,10)=5.4, p<0.05). This interaction was and score at bottom if the amount of F due to the fact that only in the WORD condi- information surpasses their capacities. In one tion performance of trial 5 was better than trial condition (WORD), word pairs were printed 1 and dropped significantly after 20 minutes. on white sheet (for example, BUTTER- Recall of pictorial material was generally LANDSCAPE). The other condition (PICT) better than recall of words alone ( (1,5)=8.9, consisted of both words and line drawings rep- F p<0.05). Finally, patients’ performance was resenting the concepts (for example, the better on day 2 compared with day 1 picture of an APPLE on the head of a NUN). ( (1,5)=6.3, p<0.05). On two consecutive days, patients partici- F These results are representative of the whole pated in a total of four experimental sessions. study group. Five patients performed better in Each session consisted of five learning trials of the PICT condition than the WORD condi- either the WORD or PICT condition followed tion, whereas one patient scored equally on by a 20 minute delayed recall. In each of the both conditions. All six patients were better on five learning trials, patients first saw every item trial 5 than trial 1. Finally, five patients were for 5 seconds and attempted to read it aloud. If better on day 2 than day 1, and one patient a patient did not succeed at reading, words scored equally on both days. This pattern were read aloud by the investigator. Immedi- implies that the eVects found were stable and ately after presentation of the entire list, in both not biased by extreme distribution of scores conditions the first word of the word pair was across patients. presented in written form only and subjects were asked to recall the second word. Presenta- tion of items was random in every trial. Twenty Discussion http://jnnp.bmj.com/ minutes later without further learning a Patients in this study showed a residual ability delayed recall followed. Beginning with the to learn simple associations and to retain some WORD condition, WORD and PICT were information for 20 minutes. Performance in the learned in two separate sessions on day 1. This immediate recall during five learning trials procedure was repeated on day 2, using the increased significantly only in the WORD con- same word lists. dition. This was due to the relatively good recall in the PICT condition already in the first STATISTICAL ANALYSIS learning trial. A ceiling eVect precluded further on October 2, 2021 by guest. Protected copyright. Because considerable variation of the data was increase in performance. A second finding was expected, the raw scores were square root that overall performance was better on the sec- transformed. A three way repeated measures ond day. Finally, there was an eVect of experi- analysis of variance (ANOVA) with main mental condition with pictorial material lead- factors of experimental condition ing to better retention than verbal material. (WORD×PICT), learning trial (trial 1×trial Cognitive functions in the acute stages after 5×delayed recall), and day (day 1×day2)was coma are rarely the subject of experimental performed. Significant interactions were ana- investigation. This lack of research is due to the lysed using post hoc t tests with Bonferroni fact that confused or disoriented patients are corrected significance levels. often unable to cooperate. For the same reason, five of our 11 patients had to be excluded from Results the study. Several studies investigated memory The figure shows that patients were able to impairment in post-traumatic amnesia. Post- learn progressively more word pairs across five traumatic amnesia is defined as the period after learning trials and that they recalled some traumatic brain injury during which patients information even after 20 minutes (trials are unable to store ongoing events.7 It is a F(2,10)=12.0, p<0.01). This eVect diVered in related but not identical concept to acute con- the two experimental conditions, as reflected fusional state, and some patients with post- J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.65.3.390 on 1 September 1998.
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