Effects of retroactive and proactive interference on word list recall in schizophrenia.

Schizophrenia spectrum patients (N = 143) and healthy controls (N = 160) were administered the Rey Auditory Verbal Learning Test (RAVLT) and tests of executive functioning to directly investigate the effects of proactive interference (PI) and retroactive interference (RI) on word list recall. It was hypothesized that by virtue of the predicted preferential association between executive functioning and RI (relative to PI), patients would demonstrate increased susceptibility to RI in their ability to recall word lists. Results indicated that patients show increased susceptibility to RI relative to PI. Furthermore, this difference appeared to be related to the frontally-mediated central executive functions that were preferentially associated with RI but not PI susceptibility.     

Impairment of verbal memory and learning in antipsychotic-naïve patients with first-episode schizophrenia

BACKGROUND: Verbal memory deficits are of interest in schizophrenia because of the potential relationship to functional and anatomic mesial temporal lobe pathology in this disorder. The goal of this study was to characterize the nature of verbal memory impairments in antipsychotic-na?ve schizophrenic patients early in the course of illness. METHODS: Neuroleptic-na?ve patients with schizophrenia (n=62) and healthy individuals (n=67), matched on IQ, age, sex, and parental socioeconomic status, were administered the California Verbal Learning Test (CVLT). RESULTS: Schizophrenia participants performed significantly worse than healthy individuals on measures of verbal learning, short- and long-term memory, and immediate attention. Deficits in recall were related to reduced use of organizational strategies to facilitate verbal encoding and retrieval. No group differences were found in rate of forgetting or susceptibility to proactive or retroactive interference. Memory deficits had minimal relation to positive or negative symptom severity. CONCLUSIONS: Schizophrenia is characterized by significant verbal memory dysfunction early in the course of illness prior to treatment with antipsychotic medications. Deficits in consistency of learning over several trials, as well as a strong relationship between semantic organizational strategies and reduced learning capacity, implicate prefrontal dysfunction as a contributor to verbal memory deficits in schizophrenia.     

Deficits in memory strategy use are related to verbal memory impairments in adolescents with schizophrenia-spectrum disorders

OBJECTIVE: To assess the nature of learning and verbal memory deficits in adolescents with schizophrenia-spectrum disorders (SzS) (i.e., schizophrenia, schizoaffective disorder, and schizophreniform disorder). METHOD: Sixty patients with SzS (mean age=16.1 years, S.D. = 2.2) and 60 age- and gender-matched diagnosis-free healthy volunteers were assessed using the California Verbal Learning Test (CVLT). Planned analyses were conducted to assess the following aspects of memory: span of apprehension, verbal learning, short-term and long-term memory, rate of forgetting, interference, and organizational strategies. Adolescents with schizophrenia (Sz) were compared to those with schizoaffective disorder (SzA). Second, patients' test profiles were compared to those of controls. Relationships between initial learning and overall verbal learning with organizational strategy were explored. RESULTS: Neurocognitive profiles did not significantly differ between Sz and SzA participants. Patients performed significantly worse than healthy comparison subjects on measures of span of apprehension, verbal learning, short- and long-term memory, and organizational strategies after adjusting for differences in premorbid intelligence. No group differences were found in rate of forgetting or susceptibility to proactive or retroactive interference. CONCLUSIONS: Adolescents with SzS are characterized by significant verbal memory dysfunction similar to what has been observed in adults with first-episode schizophrenia. Deficits in consistency of learning over several trials, as well as a strong relationship between semantic organizational strategies and reduced learning capacity, implicate dysfunction of the dorsolateral prefrontal cortex as a contributor to verbal memory deficits in adolescents with SzS.     

Exploring semantic memory by investigating buildup and release of proactive interference in healthy older adults and individuals with dementia of the Alzheimer type.

There is debate regarding the integrity of semantic memory in dementia of the Alzheimer type (DAT). One view argues that DAT is associated with a breakdown in semantic memory; the other argues that DAT is associated with predominantly preserved semantic memory and a breakdown in retrieval. The classic release from proactive interference (RPI) paradigm was used to shed light on this debate. Individuals with early-stage DAT (n = 36) and healthy older adult controls (n = 45) participated in an RPI paradigm. Each trial was a Brown-Peterson task in which participants read three-word lists, counted (for 0, 3, 6, or 9 s), and recalled the words. Both groups showed significant proactive interference (PI), but the size of the PI was significantly smaller in the DAT group. The group difference in PI may be due to the faster forgetting rate in the DAT group. Both groups showed significant RPI and there was no group difference in size when RPI was considered in terms of PI levels. Both groups showed PI and RPI in prior list intrusions. The DAT group's significant buildup and release of PI based on semantic categories suggest predominantly preserved semantic memory activity, at least, in early-stage DAT individuals.     

Material-specific retroactive interference effects of the Wechsler Adult Intelligence Scale–Fourth Edition on the Wechsler Memory Scale–Fourth Edition in a nonclinical sample

Introduction: This study investigated proactive and retroactive interference effects between the Wechsler Memory Scale–Fourth Edition (WMS–IV) using the flexible approach, and the Wechsler Adult Intelligence Scale–Fourth Edition (WAIS–IV). Method: One hundred and eighty nonclinical participants were assigned to a four (visual interference, verbal interference, visual and verbal interference, vs. no interference) by two (retroactive vs. proactive) between-subjects design. The administration order of the tests was counterbalanced (i.e., administration of the WAIS–IV prior to the WMS–IV, and the WAIS–IV administered during the delay interval of the WMS–IV). Results: The WAIS–IV produced significant retroactive interference effects on the WMS–IV; however, no proactive interference effect was observed. The retroactive interference effect was dependent on material specificity. Conclusions: The results indicate that material presented within the delay of the WMS–IV can have a significant effect on subsequent delayed recall. Clinicians should carefully consider the effects associated with carry-over effects of these tests when using them in combination.     

Does “thinking about thinking” interfere with memory? An experimental memory study in obsessive–compulsive disorder

Neuropsychological assessments of participants with obsessive–compulsive disorder (OCD) indicate impaired verbal memory if to be remembered material has to be organized. People with OCD also tend to focus their attention on their thoughts (heightened cognitive self-consciousness). We tested the hypothesis that cognitive self-consciousness causes verbal memory deficits by provoking a division of attention between study task and thoughts. Thirty-six participants with OCD, 36 matched healthy controls and 36 participants with major depressive disorder (MDD) learned under proactive interference in three study conditions: single-task condition, condition with heightened cognitive self-consciousness and condition with an external secondary task. Memory was impaired in the cognitive self-consciousness condition compared to both other conditions. Independent of condition, participants with OCD showed a reduced memory performance compared to healthy controls, but did not differ from participants with MDD. Our results are in line with the hypothesis that cognitive self-consciousness causes memory impairment.     

Semantic interference deficits and the detection of mild Alzheimer's disease and mild cognitive impairment without dementia.

Impairment in delayed recall has traditionally been considered a hallmark feature of Alzheimer's disease (AD). However, vulnerability to semantic interference may reflect early manifestations of the disorder. In this study, 26 mildly demented AD patients (mild AD), 53 patients with mild cognitive impairment without dementia (MCI), and 53 normal community-dwelling elders were first presented 10 common objects that were recalled over 3 learning trials. Subjects were then presented 10 new semantically related objects followed by recall for the original targets. After controlling for the degree of overall memory impairment, mild AD patients demonstrated greater proactive but equivalent retroactive interference relative to MCI patients. Normal elderly subjects exhibited the least amount of proactive and retroactive interference effects. Recall for targets susceptible to proactive interference correctly classified 81.3% of MCI patients and 81.3% of normal elderly subjects, outperforming measures of delayed recall and rate of forgetting. Adding recognition memory scores to the model enhanced both sensitivity (84.6%) and specificity (88.5%). A combination of proactive and retroactive interference measures yielded sensitivity of 84.6% and specificity of 96.2% in differentiating mild AD patients from normal older adults. Susceptibility to proactive semantic interference may be an early cognitive feature of MCI and AD patients presenting for clinical evaluation.     

Fatigue and declines in cognitive functioning in multiple sclerosis

OBJECTIVE: To determine whether cognitive fatigue, defined as a decline in cognitive performance over a single testing session, could be identified in MS. METHODS: Forty-five individuals with MS and 14 healthy control participants completed a 4-hour session of cognitive testing that involved a baseline neuropsychological battery, a continuous effortful cognitive task (completing mental arithmetic problems administered on a computer), and a repeat neuropsychological battery. Self-report measures of fatigue and affect were completed before each step of the testing session. RESULTS: The pattern of change in cognitive performances over the testing session significantly differed between the MS and control participants. Individuals with MS showed declines on measures of verbal memory and conceptual planning, whereas the control participants showed improvement. Although there were no significant differences between the groups on any of the baseline cognitive measures, the MS participants performed worse than the control subjects on tests of visual memory, verbal memory, and verbal fluency that were repeated following the continuous effortful cognitive task. Both MS and control participants reported increased mental and physical fatigue across the testing session compared with their baseline values. CONCLUSION: Individuals with MS show declines in cognitive performance during a single testing session and fail to show the improvement exemplified by healthy control subjects.     

Verbal learning and memory deficits in traumatic brain injury: encoding, consolidation, and retrieval

The present study examined the nature of verbal memory deficits in individuals with traumatic brain injury (TBI) compared to healthy controls. The study was designed to control for methodological shortcomings of previous related research. Three groups of participants were used: (a) a head injured sample with moderate to severe traumatic brain injuries (N=55), (b) a control sample matched on age and initial performance on CVLT Trial 5 and Sum of Trials 1 to 5 (N=55), and (c) a control sample matched on age, education, and race, but not on initial CVLT learning performance (N=55). Current findings indicate that: (a) rate of learning was comparable across groups, consistent with no encoding differences, (b) TBI patients have a significantly more rapid rate of forgetting of new information than either acquisition-matched or demographic-matched controls, consistent with consolidation problems in TBI, (c) TBI patients have less proactive interference than demographic-matched control participants, consistent with a consolidation problem in the TBI group, (d) TBI patients and acquisition-matched controls have comparably low rates of proactive interference, consistent with impaired acquisition in both of these groups, and (e) TBI patients and controls do not differ in the benefit experienced from semantic or recognition retrieval cues, consistent with no differences in retrieval processes. These data support an impaired consolidation hypothesis, rather than encoding or retrieval deficits, as the primary deficit underlying memory impairment in TBI.     

Verbal Learning and Memory Deficits in Traumatic Brain Injury: Encoding,Consolidation, and Retrieval

The present study examined the nature of verbal memory deficits in individuals with traumatic brain injury (TBI) compared to healthy controls. The study was designed to control for methodological shortcomings of previous related research. Three groups of participants were used: (a) a head injured sample with moderate to severe traumatic brain injuries (N=55), (b) a control sample matched on age and initial performance on CVLT Trial 5 and Sum of Trials 1 to 5 (N=55), and (c) a control sample matched on age, education, and race, but not on initial CVLT learning performance (N=55). Current findings indicate that: (a) rate of learning was comparable across groups, consistent with no encoding differences, (b) TBI patients have a significantly more rapid rate of forgetting of new information than either acquisition-matched or demographic-matched controls, consistent with consolidation problems in TBI, (c) TBI patients have less proactive interference than demographic-matched control participants, consistent with a consolidation problem in the TBI group, (d) TBI patients and acquisition-matched controls have comparably low rates of proactive interference, consistent with impaired acquisition in both of these groups, and (e) TBI patients and controls do not differ in the benefit experienced from semantic or recognition retrieval cues, consistent with no differences in retrieval processes. These data support an impaired consolidation hypothesis, rather than encoding or retrieval deficits, as the primary deficit underlying memory impairment in TBI.     

Are all subcortical dementias alike? Verbal learning and memory in Parkinson's and Huntington's disease patients

The utility of the concept of 'subcortical dementia' was investigated by comparing the verbal learning and memory abilities of Parkinson's disease (PD) patients with those of Huntington's disease (HD) patients. Many similarities between the PD and HD groups emerged, including impaired immediate memory spans, inconsistency of recall across learning trials, deficient use of a semantic clustering learning strategy, elevated intrusion rates on delayed recall, impaired recognition memory performance, normal retention of information over delay periods, normal vulnerability to proactive or retroactive interference, and normal types of intrusion errors. The HD subjects, however, displayed inferior free recall, deficient improvement across learning trials, abnormal serial position recall effects, higher perseveration rates, and supranormal improvement on recognition testing compared with free recall. Implications of these results for characterizing memory deficits associated with subcortical system dysfunction are discussed.     

List-learning and verbal memory profiles in childhood epilepsy syndromes

Findings of material-specific influences on memory performance in pediatric epilepsy are inconsistent and merit further investigation. This study compared 90 children (aged 6 years to 16 years) with childhood absence epilepsy (CAE), frontal lobe epilepsy (FLE), and temporal lobe epilepsy (TLE) to determine whether they displayed distinct list-learning and verbal memory profiles on the California Verbal Learning Test — Children's Version (CVLT-C). Group comparison identified greater risk of memory impairment in children with TLE and FLE syndromes but not for those with CAE. While children with TLE performed worst overall on Short Delay Free Recall, groups with TLE and FLE performed similarly on Long Delay Free Recall. Contrast indices were then employed to explore these differences. Children with TLE demonstrated a significantly greater retroactive interference (RI) effect compared with groups with FLE and CAE. Conversely, children with FLE demonstrated a significantly worse learning efficiency index (LEI), which compares verbal memory following repetition with initial recall of the same list, than both children with TLE and CAE. These findings indicated shallow encoding related to attentional control for children with FLE and retrieval deficits in children with TLE. Finally, our combined sample showed significantly higher rates of extreme contrast indices (i.e., 1.5 SD difference) compared with the CVLT-C standardization sample. These results underscore the high prevalence of memory dysfunction in pediatric epilepsy and offer support for distinct patterns of verbal memory performance based on childhood epilepsy syndrome.     

Long-term memory and levels-of-processing in autism

Prior studies reported that long-term memory (LTM) was basically unimpaired in individuals with autism. However, people with autism have been found to perform worse than ability-matched controls when verbal materials to be remembered are semantically related. In normal subjects, semantic processing of verbal materials facilitates LTM better than 'shallow' (phonological or perceptual) processing, which is known as the levels-of-processing effect. In this study, the relationship between LTM and semantic processing was investigated using a levels-of-processing task. In Study 1, a levels-of-processing task was conducted on healthy volunteers, which confirmed the levels-of-processing effect with our task. In study 2, the same task was conducted on autistic subjects with mild or no mental retardation and ability-matched controls. The levels-of-processing effect was confirmed in the control group. Although overall performance in the two groups was comparable, the levels-of-processing effect was not found in the autistic group. LTM resulting from perceptual processing was better in the autistic group than in the control group, indicating superior "rote memory" in individuals with autism. Furthermore, the pattern of correlations between LTM performance and cognitive measures differed greatly between the two groups. The lack of the levels-of-processing effect, which has not been reported in other psychiatric or neuropathological conditions, suggests an abnormal relationship between semantic memory and episodic memory in individuals with autism.     

Relationships between measures of auditory verbal learning and executive functioning

Abstract

Relationships between performance on the California Verbal Learning Test (CVLT) and executive abilities were examined. In a sample of 115 neurological cases principal components factor analysis produced five theoretically and clinically meaningful CVLT factors. The five CVLT factors reflected general verbal learning (CVLT1), response discrimination (CVLT2), a proactive interference effect or “working memory” (CVLT3), serial learning strategy (CVLT4), and a retroactive interference effect (CVLT5). Canonical correlation between executive function measures and the five CVLT factor scores yielded one significant canonical variable accounting for 29 percent of the variance in the data. Two CVLT factors (CVLT1 and CVLT3), the Trail Making Test Part B, and Digit Span were significantly correlated with the canonical variate. Higher levels of memory performance were associated with better attention and mental tracking. Based on the present findings, attentional aspects of executive abilities appear to play a role in learning and working memory. Other aspects of executive abilities (abstraction, problem-solving, planning) appear to have minimal relationships with memory processes.     

Behavioral assessment of social competence following severe head injury

Abstract

The utility of the concept of «subcortical dementia» was investigated by comparing the verbal learning and memory abilities of Parkinson's disease (PD) patients with those of Huntington's disease (HD) patients. Many similarities between the PD and HD groups emerged, including impaired immediate memory spans, inconsistency of recall across learning trials, deficient use of a semantic clustering learning strategy, elevated intrusion rates on delayed recall, impaired recognition memory performance, normal retention of information over delay periods, normal vulnerability to proactive or retroactive interference, and normal types of intrusion errors. The HD subjects, however, displayed inferior free recall, deficient improvement across learning trials, abnormal serial position recall effects, higher perseveration rates, and supranormal improvement on recognition testing compared with free recall. Implications of these results for characterizing memory deficits associated with subcortical system dysfunction are discussed.     

Memory failure in Huntington's disease

Patients with Huntington's disease (HD) were compared to normal controls of equivalent age and verbal intelligence on a set of verbal learning tasks. Although the HD patients showed the expected deficit in secondary (long-term) memory, their performance was otherwise comparable to that of the control groups. Primary (short-term) memory was normal, there was normal sensitivity to proactive interference, and the patients showed an advantage, albeit reduced, in recall of related compared to unrelated word lists. The findings suggest that mnemonic input is encoded semantically in HD though less efficiently than in unafflicted individuals, and that difficulty accessing information in semantic (knowledge-based) memory may be partially responsible for the memory disorder of HD.     

Consolidation deficits in traumatic brain injury: The core and residual verbal memory defect

While memory deficits are consistently found to be a salient problem in individuals with moderate to severe traumatic brain injury (TBI), the specific memory processes (i.e., encoding, consolidation, and retrieval) underlying the verbal memory deficit are disputed in the literature. The current study evaluated the recovery of these verbal memory processes over time. A TBI patient group evaluated acutely after the injury (baseline) and again at 6 months and 1 year post injury was compared to a demographically similar control group evaluated only once. The current results replicated previous findings in support of an impaired consolidation hypothesis as the primary deficit underlying memory impairment in TBI. These deficits are reflected in relatively more rapid forgetting through 1 year post injury and relatively less proactive interference up to 6 months post injury.     

Questioning the rule of thumb: can verbal tasks be administered during the CVLT-II delay interval?

In the manual for the California Verbal Learning Test - II (CVLT-II), the authors suggest that nonverbal, rather than verbal, tasks be administered during the delay interval between administrations of the Short- and Long-Delay Recall trials of this test. They contend that this method minimizes the retroactive interference produced by intervening tasks. The purpose of the current study was to compare the extent to which verbal and nonverbal intervening tasks produce retroactive interference on CVLT-II List A recall following the long-delay. Participants in the present study were 120 undergraduate students. All participants completed the CVLT-II, and were randomly assigned to a group in which they were administered either a verbal (WAIS-III Vocabulary or Peabody Picture Vocabulary Test - IIIB) or nonverbal (Raven's Standard Progressive Matrices or WAIS-III Block Design) intervening task during the long-delay interval of the CVLT-II. Statistical analyses revealed that regardless of the type of intervening task given, participants in all groups recalled the same number of words and produced a similar number of intrusions during the CVLT-II recall trials. This indicates that not all verbal tasks produce retroactive effects beyond those produced by nonverbal tasks.     

Questioning the Rule of Thumb: Can Verbal Tasks be Administered During the CVLT-II Delay Interval?

In the manual for the California Verbal Learning Test - II (CVLT-II), the authors suggest that nonverbal, rather than verbal, tasks be administered during the delay interval between administrations of the Short- and Long-Delay Recall trials of this test. They contend that this method minimizes the retroactive interference produced by intervening tasks. The purpose of the current study was to compare the extent to which verbal and nonverbal intervening tasks produce retroactive interference on CVLT-II List A recall following the long-delay. Participants in the present study were 120 undergraduate students. All participants completed the CVLT-II, and were randomly assigned to a group in which they were administered either a verbal (WAIS-III Vocabulary or Peabody Picture Vocabulary Test - IIIB) or nonverbal (Raven's Standard Progressive Matrices or WAIS-III Block Design) intervening task during the long-delay interval of the CVLT-II. Statistical analyses revealed that regardless of the type of intervening task given, participants in all groups recalled the same number of words and produced a similar number of intrusions during the CVLT-II recall trials. This indicates that not all verbal tasks produce retroactive effects beyond those produced by nonverbal tasks.     

Retroactive interference of object‐in‐context long‐term memory: Role of dorsal hippocampus and medial prefrontal cortex

Retroactive interference (RI) is a type of amnesia in which a new learning experience can impair the expression of a previous one. It has been studied in several types of memories for over a century. Here, we aimed to study in the long‐term memory (LTM) formation of an object‐in‐context task, defined as the recognition of a familiar object in a context different to that in which it was previously encountered. We trained rats with two sample trials, each taking place in a different context in association with different objects. Test sessions were performed 24 h later, to evaluate LTM for both object‐context pairs using separate groups of trained rats. Furthermore, given the involvement of hippocampus (Hp) and medial prefrontal cortex (mPFC) in several recognition memories, we also analyzed the participation of these structures in the LTM formation of this task by the local infusion of muscimol. Our results show that object‐in‐context LTM formation is sensitive to RI by a different either familiar or novel object‐context pair trial, experienced 1 h later. This interference occurs in a restricted temporal window and works on the LTM consolidation phase, leaving intact short‐term memory expression. The second sample trial did not affect the object recognition part of the memory. Besides, muscimol treatment before the second sample trial blocks its object‐in‐context LTM and restores the first sample trial memory. We hypothesized that LTM‐RI amnesia is probably caused by resources or cellular machinery competition in these brain regions when they are engaged in memory formation of the traces. In sum, when two different object‐in‐context memory traces are being processed, the second trace interferes with the consolidation of the first one requiring mPFC and CA1 dorsal Hp activation. © 2014 Wiley Periodicals, Inc.