Eli Vakil

The effect of moderate to severe traumatic brain injury (TBI) on different aspects of memory: a selective review.

Deficient learning and memory are frequently reported as a consequence of traumatic brain injury (TBI). Because of the diffuse nature of the injury, patients with TBI are not the ideal group for studying brain-behavior relations. Nevertheless, characterization of the memory breakdown following TBI could contribute to the assessment and rehabilitation of this patient population. It is well documented that memory is not a unitary system. Accordingly, in this article I review studies that have investigated the long-term effect of moderate to severe TBI on different memory aspects, including explicit and implicit tests of memory. This review demonstrates that TBI affects a large range of memory aspects. One of the conclusions is that the memory impairment observed in TBI patients could be viewed, at least to some degree, as a consequence of a more general cognitive deficit. Thus, unlike patients suffering from global amnesia, memory in patients with TBI is not selectively impaired. Nevertheless, it is possible to detect a subgroup of patients that do meet the criteria of amnesia. However, the most common vulnerable memory processes following TBI very much resemble the memory deficits reported in patients following frontal lobe damage, e.g., difficulties in applying active or effortful strategy in the learning or retrieval process. The suggested similarity between patients with TBI and those suffering from frontal lobe injury should be viewed cautiously; considering the nature of TBI, patients suffering from such injuries are not a homogeneous group. In view of this limitation, the future challenge in this field will be to identify subgroups of patients, either a priori according to a range of factors such as severity of injury, or a posteriori based on their specific memory deficit characteristics. Such a research approach has the potential of explaining much of the variability in findings reported in the literature on the effect of TBI on memory. This work was supported by the Paula Rich Multidisciplinary Center in Mind, Brain and Behavior, Bar-Ilan University, Ramat-Gan, Israel. The author thanks Mr. Judah Koller for his help with the preparation of the tables.

Rey Auditory-Verbal Learning Test: Structure Analysis.

One of the major advantages of the Rey Auditory-Verbal Learning Test (AVLT) is its multiple measures of learning and memory. This study evaluated empirically whether the different scores are, in fact, not merely different expressions of a single factor, but, rather, measures of different memory domains. The Rey AVLT was administered to 146 normal subjects. Factor analyses produced one, two, or three factors depending on the combination of scores included in the analysis and on the criteria used to determine the number of factors. The basic factors identified were acquisition and retention. The latter can be subdivided further into storage and retrieval, thus yielding a total of three factors.

Comparison of the predictive power of socio-economic variables, severity of injury and age on long-term outcome of traumatic brain injury: sample-specific variables versus factors as predictors.

The primary objective of this study was to measure the predictive power of pre-injury socio-economic status (SES), severity of injury and age variables on the very long-term outcomes of traumatic brain injury (TBI). By applying a within-subjects retroactive follow-up design and a factor analysis, the study also compared the relative power of sample-specific predictors to that of more commonly used variables and conceptually based factors. Seventy-six participants with severe TBI were evaluated at an average of 14 years post-injury with an extensive neuropsychological battery. The results show that pre-injury SES variables predict long-term cognitive, psychiatric, vocational, and social/familial functioning. Measures of severity of injury predict daily functioning, while age at injury fails to predict any of these variables. Sample-specific predictors were more powerful than more commonly used predictors. Implications regarding long-term clinically based and conceptually based prediction, and those regarding comparisons of predictors across samples are further discussed.

Interpretation of Facial Expressions of Affect in Children with Learning Disabilities with Verbal or Nonverbal Deficits

The ability to identify facial expressions of happiness, sadness, anger, surprise, fear, and disgust was studied in 48 nondisabled children and 76 children with learning disabilities aged 9 through 12. On the basis of their performance on the Rey Auditory-Verbal Learning Test and the Benton Visual Retention Test, the LD group was divided into three subgroups: those with verbal deficits (VD), nonverbal deficits (NVD), and both verbal and nonverbal.

Unawareness of Cognitive Deficits and Daily Functioning Among Persons With Traumatic Brain Injuries

This study examines levels of unawareness of cognitive deficits and their relationship to functional outcome among persons with traumatic brain injury (TBI). Data from 61 persons with TBI and 34 family members consisting of various measures were used. The results suggest that awareness of cognitive deficits is not differentially distributed along a concrete- continuum of cognitive domains. Awareness in this sample was significantly related to psychiatric symptomatology and partially associated with behavior disturbances and daily functioning, but not with vocational outcomes. Persons with TBI who over-estimated their cognitive abilities were found to function worse on most outcome measures, except vocation, than persons who did not overestimate their abilities.

Which verbal fluency measure is most useful in demonstrating executive deficits after traumatic brain injury

This paper examines switching and clustering in phonemic and semantic fluency tasks in individuals with traumatic brain injury (TBI). Fluency tasks were administered to 30 Hebrew-speaking patients with TBI and 30 age-matched control participants. Significant group differences were found in total output, number of switches, and number of clusters on both tasks, but not in mean cluster size. Unlike prediction, z scores of the number of semantic switches and clusters were lower than the equivalent z scores on the phonemic test. Results highlight the executive component of semantic fluency and the importance of using this task when assessing cognitive functioning after TBI.

Normative Data for Composite Scores for Children and Adults Derived from the Rey Auditory Verbal Learning Test

Norms on seven composite scores derived from the Rey Auditory Verbal Learning Test (AVLT) are reported here. These scores reflect a variety of verbal memory processes: learning, interference, retention over time, and retrieval efficiency. The norms are based on 943 children ranging in age from 8 to 17 years, divided into 10 age cohorts, and 528 adults, ranging in age from 21 to 91 years, divided into 6 age cohorts. Overall, the learning measures were the most sensitive to age. The most significant changes in memory as measured with these composite scores took place in the very young and very old age groups. These changes may be attributable to frontal lobe maturation in youth and deterioration in old age. Female participants show superiority over male participants on various verbal memory measures. These norms on the composite scores are primarily expected to serve the clinician in the process of memory assessment by supplementing the existing norms on individual trials of the Rey AVLT.

Automatic temporal order judgment : the effect of intentionality of retrieval on closed-head-injured-patients

Closed-head-injured (CHI) and control groups were tested on a temporal order task under intentional and incidental retrieval conditions. Subjects were given five presentations of a list of nouns. In the incidental retrieval condition, subjects were told that they were to remember the words but that the order was not important. In the intentional retrieval condition, subjects were given the words in an order different from that in which they were originally presented and were asked to reorder the words to match the original order. For both conditions we compared the order in which words were recalled to the order in which they were originally presented. The results suggest that temporal order memory had more effortful characteristics in the intentional than in the incidental retrieval condition. The two groups did not differ significantly in the incidental retrieval condition. However, while the control group showed a significant improvement in the intentional retrieval condition. CHI groups performance did not significantly change. This study highlights two major points: (1) intentionality at the retrieval stage determines the effortfulness with which information is processed; (2) the more automatic the tasks, the better it is preserved following closed-head injury.

Declarative and procedural learning in Parkinson's disease patients having tremor or bradykinesia as the predominant symptom

The distinction between procedural and declarative memory is widely accepted in the memory literature. Converging evidence makes a strong case that the medial aspects of the temporal lobes and the diencephalon subserve the declarative memory system. However, the neuroanatomy of procedural memory is much less clear. In animal studies, damage to the basal ganglia has been found to affect procedural memory, but studies of patients suffering from degenerative diseases of the basal ganglia (e.g., Parkinsons and Huntingtons disease) are less conclusive. Two groups of Parkinsons disease subtypes, with tremor (PDt) and bradykinesia (PDb) as the predominant motor symptom, were compared to controls on declarative and procedural memory tasks. The two patient groups did not differ from each other on the declarative tasks. However, in the procedural learning tasks, the PDb but not the PDt group, was significantly impaired compared to the control group. The results are discussed in terms of the differential involvement of discrete neuroanatomic loops connecting the basal ganglia and the prefrontal cortex.

Plasma homocysteine levels and parkinson disease : Disease progression, carotid intima-media thickness and neuropsychiatric complications

Objective: To determine whether plasma homocysteine (Hcy) levels are associated with clinical characteristics, neuropsychological and psychiatric manifestations and cardiovascular comorbidity in patients with Parkinson disease (PD). Background: Elevated Hcy levels are linked to atherosclerosis, vascular disease, depression, and dementia. Patients with PD treated with L-dopa have been shown to have elevated Hcy levels. Design/Methods: Idiopathic PD patients were evaluated using the Unified Parkinsons Disease Rating Scale, Hoehn and Yahr stage, Parkinson Psychosis Rating Scale, Beck Depression Inventory, Frontal Assessment Battery, Mini-Mental Status Examination, and several tests for frontal type cognitive functions. Fasting blood samples were collected for the measurement of Hcy, and carotid B-mode ultrasound was performed to measure intima-media thickness of the common carotid arteries. Results: Seventy-two consecutive PD patients (46 men; average age, 68.7 ± 11.6 years; average disease duration, 7.0 ± 4.7 years) were recruited. All but 10 patients were treated with L-dopa. The average level of Hcy was 16.4 ± 7.8 &mgr;mol/L, and 38.9% of the patients had Hcy level above the reference range (>15.0 &mgr;mol/L). The Hcy levels were associated with PD duration as they were with L-dopa treatment duration but were not associated with the parameters of disease severity or with L-dopa dose. The Hcy levels were associated neither with the common carotid intima-media thickness nor with cardiovascular morbidity. No association was found between Hcy and the neuropsychiatric features of PD such as depression, cognitive performance, or psychosis. Conclusions: Hyperhomocystinemia is common in L-dopa-treatedPD patients but was not associated with neuropsychological complications (depression, dementia, and cognitive decline associated with frontal lobe functioning or psychosis), enhanced disease severity, or vascular comorbidity.