Neuropsychological test profiles in schizophrenia and non-psychotic depression.

OBJECTIVE: The study examined to what degree schizophrenia is characterized by a neuropsychological (NP) test profile specific in shape and level compared with depression and normal functioning. METHOD: Fifty-three patients with schizophrenia, 45 with non-psychotic depression, and 50 normals were assessed with a comprehensive NP test battery and clinical instruments. NP test scores were factor analyzed into seven composite scores. RESULTS: Schizophrenia patients performed significantly below normals across all seven composite scores, whereas depression patients were impaired in two. Verbal memory was most impaired. Sixty-two percent of schizophrenia patients were moderately or severely impaired, the corresponding figure for depression was 28%. Impairment was moderately associated with IQ level and clinical symptom load in schizophrenia, but not in depression. CONCLUSION: Schizophrenia is characterized by deficits across a wide range of NP functions. Thirty-eight percent of the patients are within normal limits. A mild and limited NP disturbance is apparent in depression.

Cortisol level predicts executive and memory function in depression, symptom level predicts psychomotor speed.

OBJECTIVE: On a group level depression is related to hypercortisolism and to psychomotor retardation, executive dysfunction and memory impairment. However, intra-group heterogeneity is substantial. Why some are impaired while others remain in the normal range, is not clear. The present study aims at discerning the relative contribution of present symptom severity and hypercortisolism to impairment in the three domains of cognition. METHOD: Morning saliva cortisol was measured in 26 subjects with recurrent major depression prior to a neuropsychological examination with tests known to be sensitive to cognitive impairment in depression. RESULTS: Cortisol level correlated with executive dysfunction and post-encoding memory deficits, but not with processing speed. Depression level correlated with processing speed. These patterns remained significant after controlling for confounders through partial correlations. CONCLUSION: The association between cortisol and cognition is not an artifact of psychiatric symptom load. High level of saliva cortisol is associated with aspects of cognition that can be dissociated from psychomotor retardation, which is dependent on symptom load.

General psychopathology is more important for executive functioning than diagnosis.

OBJECTIVE: Impaired executive functioning (EF) has often been reported in patients with major depression or schizophrenia. We hypothesize that the variance in EF is more affected by level of general psychopathology than by diagnosis. METHOD: Forty-three patients with major depression and 47 with schizophrenia were included. EF was measured with Wisconsin Card Sorting Test, Stroop Colour Word Test, Paced Auditory Serial Addition Test, Digits Backwards and Controlled Oral Word Association Test. The level of general psychopathology was measured with Brief Psychiatric Rating Scale - Expanded and Positive and Negative Syndrome Scale, the General psychopathology subscale. RESULTS: The level of general psychopathology predicted more of the variance in EF than diagnosis. In multivariate analyses, the effect of general psychopathology on EF was more robust for adjustment for diagnosis than vice versa. CONCLUSION: Future research on cognitive functioning in psychiatric patients should include level of general psychopathology to avoid overemphasising effects of diagnoses.

Attention profile in schizophrenia compared with depression: differential effects of processing speed, selective attention and vigilance.

OBJECTIVE: The aim of the study is to investigate whether subjects with schizophrenia and major depression display attention deficits for different reasons. METHOD: Subjects with schizophrenia (n = 53), recurrent major depression (n = 50) and normal controls (n = 50) were administered with 11 measures of processing speed, selective attention and vigilance. Indices of basal speed, speeded attention, non-speeded attention and vigilance were computed. RESULTS: Both clinical groups were impaired on all chronometric tests. The schizophrenic subjects were also more impaired on speeded attention compared with basal processing speed. Only the schizophrenics were impaired on the non-speeded measures of selective attention. Compared with the schizophrenics, the depressives showed a decrement in vigilance. CONCLUSION: Reduced performance on attention tests in major depression is because of a non-specific speed reduction and loss of vigilance consistent with lack of effort. In addition to generally impaired processing speed, the schizophrenic subjects exposed a deficit in selective attention, indicating executive dysfunction.

Honig's model of working memory and brain activation: an fMRI study.

The present study investigated changes in neuronal activation with fMRI related to Honig's model of working memory, which is much less studied compared with other working memory models. In contrast to other studies which have applied recognition procedures, the primary aim with the present study was to examine brain activation when subjects had to continuously recall and forget items held in working memory. The results showed that the mid-ventrolateral frontal cortex was particularly activated in the left hemisphere, whereas the mid-dorsolateral frontal cortex was particularly activated in the right hemisphere during execution of the working memory task. The findings are discussed in relation to process- and domain-specific accounts of working memory.

Brain asymmetry for language in dyslexic children.

Studies of brain asymmetry in dyslexia have yielded mixed results both with respect to patterns of asymmetry and their cognitive correlates. This paper assessed language lateralisation inferred from dichotic listening with forced attention in a clinical group of young dyslexic subjects. As a whole the dyslexic group showed a deviant asymmetry pattern compared to a control group. Subdivision into two subgroups by receptive language abilities yielded differential patterns within the dyslexia group. Both subgroups exhibited a weaker response pattern to right ear stimuli than the control group. In addition, the subgroup with no language impairment showed bilateral language representation, whereas the subgroup with impaired receptive language abilities showed reversed dominance patterns.

Executive functions in dyslexia.

This study focused on executive functions in dyslexia. A group of 43 heavily-affected young dyslexics, divided into two groups based on the results of a receptive language test, and 20 non-dyslexic controls, were tested with a Dichotic Listening Test, the Stroop Color Word Test and the Wisconsin Card Sorting Test. The dyslexic subjects demonstrated significant impairment on all tasks, but with different patterns of impairment according to the subgrouping. The subgroups were equally impaired on the Dichotic Listening Test, but differed on the Stroop and the Wisconsin Tests. The data support a hypothesis suggesting executive problems in dyslexia, depending on receptive language skills.

Lasting auditory attention impairment after persistent middle ear infections: a dichotic listening study.

Dichotic listening performance was studied in children who at an early age had undergone a myringotomy with insertion of ventilating tubes for persistent middle ear infections (otitis media with effusion; OME) and compared with age-equivalent children who had no history of otitis media or hearing problems. The OME group consisted of 19 children with a median age of 9 years; 15 of whom were right-handed, and 14 were boys. The comparison sample comprised 18 children with a median age was 9 years 4 months. Hand preference and sex were matched with the OME group. Both groups were tested with dichotic listening to consonant-vowel syllables and additional forced-attention tasks. The comparison sample showed a weak right-ear advantage, and age-adequate attentional modulations. The children in the OME group showed a strong right-ear advantage, but were not able to modulate the ear advantage during directed-attention tasks. Models for interpreting the result are discussed.

Lasting effects of otitis media with effusion on language skills and listening performance.

Otitis media with effusion (OME) and its related hearing loss has been associated with delayed language development, particularly if the disease is recurrent or of long duration. To find out more about the long-term effects of OME on language skills and listening performance we performed a retrospective study. A group of 19 otherwise healthy 9-year-old children with an earlier history of long lasting bilateral OME were compared with an age-matched control group of 19 children with no history of OME or hearing impairment and normal otoscopy, tympanometry and audiometry. The children in the OME group had an average of 1.4 treatments with ventilation tubes. Mean hearing levels for 500, 1,000 and 2,000 Hz in the OME group were 13 dB in the right ear and 11.3 dB in the left ear. All children were examined with the Illinois test of psycholinguistic abilities (ITPA), test for articulation, Boston naming test, dichotic listening tests with additional tasks of directed attention and tests for word and sound discrimination. In the OME group we found significant lower scores in the articulation test and small, but significant, lower scores in the test regarding sound discrimination. No significant differences on other language skills were detected in the ITPA test or Boston naming test. We found a significantly higher degree of right ear advantage and lower attentional effectiveness in the OME-group.

Auditory attentional shifts in reading-disabled students: quantification of attentional effectiveness by the Attentional Shift Index.

A controversy has existed for some years regarding auditory attentional skills in reading-disabled children. Data have suggested highly developed attentional skills in groups of reading-disabled students, but reduced attentional shifts have also been documented in equivalent groups. Attentional shifts in dichotic listening with forced or directed attention are usually inferred from a significant interaction between attentional task and ear. However, this procedure cannot be used to evaluate individual test performance, and the interaction does not give a useful measure of attentional shifts in dichotic listening meaningful for comparison with other tests of attention. In this paper attentional shifts in dichotic listening are quantified with the Attentional Shift Index (ASI), a measure for evaluating the degree of attentional shift in individual subjects. The ASI is based on the log-odds ratio of hits and intrusion errors when the subject has been tested under conditions of directed or forced attention. When 58.3% of the normative sample showed significant attentional shifts, none of the reading-disabled sample did so. This finding is discussed in relation to different types of deficits that can account for for the lack of auditory attentional shifts.

Attentional bias in active smokers, abstinent smokers, and nonsmokers.

Attentional bias was studied with a modified version of the Stroop test in active smokers, abstinent smokers, and nonsmokers. The task was color-naming of incongruent color-words, smoking-related words, and neutral words. The results showed that the active smokers used longer verbal reaction time (VRT) to smoking-related words compared to abstinent smokers, i.e., indicating stronger attentional bias in the active smokers. Furthermore, longer VRTs to the Stroop words compared to the smoking words and the neutral words were found only in nonsmokers and abstinent smokers. Finally, a significant negative correlation was found between attitudes against smoking and VRTs to the smoking-related words. Taken together the main finding was that the active smokers showed no differential response to the stimuli. This could be caused by a lack of ability to modulate attentional processes in active smokers.

Biased attention and the fused dichotic words test.

This study examines the effect of biased attention on the fused dichotic words test (FDWT) and the CV syllables dichotic listening test (CVT). Eight males and eight females were given both tests with two different instructions: to direct attention to the left ear (DL), or to the right ear (DR). These instructions led to highly significant differences in response on the CVT, but only a marginal shift in performance on the FDWT. While the FDWT is not completely unaffected by attentional manipulations, it is far less influenced by such effects than the CVT. This indicates that subject-initiated shifts of attention are much less likely to affect performance on the FDWT than on other dichotic tests and makes it a more valuable task to assess cerebral speech lateralization.

Absence of ear advantage on the consonant-vowel dichotic listening test in adolescent and adult dyslexics: specific auditory-phonetic dysfunction.

The present study investigated auditory-phonetic processing in a group of adolescent and adult reading disabled subjects. Right- and left-handed dyslexic subjects were compared with an age, sex, and handedness matched control group. All subjects were studied with a consonant-vowel version of the dichotic listening task with repeated presentations of dichotically presented pairs of CV-syllables. Left and right ear correct scores were compared for ear advantage in each of the different subgroups of subjects. The main finding was the absence of an expected right-ear advantage (REA) in the right-handed dyslexic group as compared to the right-handed normal readers. Both the dyslexic and normal left-handed groups did not show a REA. The findings are discussed within a theoretical framework that focuses on a basic auditory-phonetic processing dysfunction in developmental dyslexia that persists into adulthood.

Attentional effects in dichotic listening.

This study addresses attentional effects in dichotic listening (DL) to consonant-vowel syllables. Previous research has shown that ear advantages in DL are modulated by biased attention to either the left or the right ear. Attentional effects in DL can be the result of two processes: facilitation of reports from the attended ear, or suppression of intrusions from the nonattended ear. Sixty-two students were tested with DL under three different task instructions: nonforced (divided) attention, attention forced to the right ear, and attention forced to the left ear. The main finding was inhibition of intrusions from the nonattended ear, combined with the facilitation of the correct reports from the attended ear during the two forced-attention conditions, compared with the nonforced condition. The results are discussed in relation to right hemisphere processing of dichotic input, and that attention may activate subcortically biased asymmetries which suppress input from the nonattended channel.

Hemispheric asymmetry effects in children studied by dichotic listening and visual half-field testing.

Dichotic listening (DL) and visual half-field (VHF) testing were used to study hemisphere asymmetry in a developmental perspective. Five-, 8-, and 11-year-old children were presented lists of fused words using a DL technique in Experiment 1, and 8- and 11-year-old children were presented pictures of common objects using a VHF technique in Experiment 2. In both experiments, measures of identification, free recall, and recognition of the words/pictures were employed. The results revealed effects of ear input (right-ear advantage) and half-field presentation (right visual half-field advantage) for all age groups, although the magnitude of this lateralization effect differed between the three memory measures. The results are discussed in relation to developmental aspects of language laterality, and in relation to the clinical utility of non-invasive lateralization techniques.

Manipulations of subjects' level of arousal in dichotic listening.

The effects of manipulation of the subject's level of arousal on the right ear advantage (REA) in dichotic listening to CV-syllables were investigated. There were three different arousal manipulations under high and low incentive levels. Negative manipulations involved threat of electric shock (high incentive) or noise (low incentive) for incorrect answers. Positive manipulations involved the possibility to earn a substantial (high incentive) or small (low incentive) sum of money for correct answers. A third, neutral, condition involved no specific instructions about consequences for correct or incorrect answers. Thirty-six females participated in the study. Heart rate was recorded as an independent measure of change in level of arousal as a function of the experimental instructions. The results showed that the high negative condition abolished the REA effect, with a non-significant difference between ears. This was caused by both an increase in correct left ear reports and a decrease in correct right ear reports. The other arousal conditions had no effect on the REA. The results are discussed in terms of right hemisphere dominance for aversive emotional processing in dichotic listening.

Anticipatory nausea and vomiting in cancer patients.

The present study reports on a mediating mechanism for anticipatory nausea and vomiting (ANV) in cancer chemotherapy. ANV is usually explained as a classically conditioned response. However, conditioning models have failed to explain individual variation in ANV susceptibility. On the basis of the positive correlation between degree of autonomic reactivity (AR) and conditionability, it is proposed that individual AR is predictive of ANV development. Of the 31 patients who participated in the study, 74% experienced postinfusion nausea and vomiting (PNV). Of the 23 patients who experienced PNV, 52% developed ANV. AR was recorded in a habituation paradigm before chemotherapy treatment was initiated. The patients in the ANV group showed significantly increased sympathetic reactivity as compared with the no-ANV group, implying that AR is a mediator of ANV development.

Auditory neglect after right frontal lobe and right pulvinar thalamic lesions.

Auditory unilateral neglect or extinction to simultaneous stimulation is reported in a right-handed male with a lesion in the right frontal lobe and in the right thalamic pulvinar area. The patient was submitted to stereotactic thalamotomy for a post-traumatic intentional ataxia in the left extremities. He was subjected to repeated tests with dichotic listening to consonant-vowel syllables under three different attentional instructions. He was also tested monaurally with the same stimulus materials as used in the dichotic test. The results showed almost complete extinction of the left ear input during dichotic presentations, despite normal hearing when tested with audiometer screening. The left ear extinction effect was independent of instructions to attend to the left or right ear input. However, during monaural presentation, correct left ear reports increased to about 85%. The results are interpreted as showing an auditory attentional neglect caused by the right frontal and pulvinar lesions.

Dichotic listening during forced-attention in a patient with left hemispherectomy.

A young left-handed girl with an extensive posttraumatic lesion in the left hemisphere was tested with dichotic listening (DL) under three different attentional instructions. The major aim of the study was to evaluate a structural vs attentional explanation for dichotic listening. As both her expressive and receptive language functions were intact after the lesion, it was assumed that the right hemisphere was the language-dominant one. In the free-report condition, she was free to divert attention to and to report from both ear inputs. In the forced-right condition, she was instructed to attend to and report only from the right ear input. In the forced-left condition, she was instructed to attend to and to report only from the left-ear input. Her performance was compared with data from a previously collected sample of normal left-handed females. Analysis showed that the patient, in contrast to the normal sample, revealed a complete right-ear extinction phenomenon, irrespective of attentional instruction. Furthermore, she showed superior correct reports from the left ear, compared with those of the normal sample, also irrespective of attentional instruction. It is concluded that these results support a structural, rather than attentional explanation for the right-ear advantage (REA) typically observed in dichotic listening. The utility of validating the dichotic listening technique on patients with brain lesions is discussed.