Search

Monolingual studies contrasting memory for positive versus negative emotion-laden words have generally used single-trial paradigms and have produced inconsistent results (no difference or an advantage for either positive or negative valence). However, monolingual studies with multiple presentations of stimuli have consistently found a positivity advantage in recall. No bilingual study has examined whether L2 testing, using a multi-trial procedure, will also produce a positivity advantage. We report two experiments in which L1 and L2 participants performed three learning trials (aural exposure, oral recall), followed by multiple delayed oral recall trials and a recognition trial, using lists of English words from ad-hoc semantic categories, with equal numbers of positive versus negative valence words. Results, including an overall positivity advantage, a greater positivity advantage in L2 than L1, and greater valence-based clustering in L2 than L1, were discussed in terms of the effects of stimulus exposure and gist consolidation.

Purpose The study aimed to test a combination of semantic memory and traditional episodic memory therapies on episodic memory deficits in adults with traumatic brain injury. Method Twenty-five participants who had been diagnosed with traumatic brain injury and had episodic memory deficits were randomly assigned either to a combined memory treatment group ( n = 16) or to a wait-list control group ( n = 9). Before and after treatment, they completed standardized neuropsychological testing for episodic memory and related cognitive domains, including the California Verbal Learning Test-Second Edition, the Controlled Oral Word Association Test, the University of Southern California Repeatable Episodic Memory Test, the Wechsler Abbreviated Scale of Intelligence-Second Edition Matrices, the Test of Everyday Attention, the Memory Assessment Clinics Self-Rating Scale, the Expressive Vocabulary Test-Second Edition, and the Story Recall subtest from the Rivermead Behavioural Memory Test. In addition to a traditional episodic memory therapy, the treatment group received a novel semantic memory-focused therapy, which involved participants finding meaningful connections between diverse concepts represented by sets of two or three words. Results The treatment group demonstrated statistically significant improvement in memory for list learning tasks, and there was a significant difference from pretest to posttest between the treatment group and the wait-list control group. Clinical significance was demonstrated for the treatment group using minimally important difference calculations. Conclusion Combined memory therapy resulted in significant improvements in episodic memory, semantic memory, and attention, in comparison to no treatment. Supplemental Material https://doi.org/10.23641/asha.14049968.

Background/Study Context: A number of longitudinal randomized controlled trials (LRCT) have used free verbal recall tests to study the effects of post-menopausal estrogen hormone therapy (HT) on episodic memory, but none have explicitly explored contrasts between list and story recall, in spite of cognitive differences between the tasks. For example, list recall provides little support for the use of gist, while story recall emphasizes it, and there is evidence that estrogen produces gist bias. Moreover, we present a literature tabulation that also suggests a task-specific HT effect., Methods: In an LRCT with up to eight yearly test sessions, post-menopausal women were randomly assigned either to placebo (N = 56) or to an estrogen formulation (N = 44); subgroups received either estrogen alone (hysterectomy; E-alone; N = 16) or with progestin (intact uterus; E + P; N = 28). Participants were tested on the immediate and delayed list and story recall at each session., Results: Linear mixed effects analyses of longitudinal trajectories showed that relative to placebo, the HT group declined significantly faster on immediate list recall and slower on immediate story recall. Separate analyses produced a sharpened version of this pattern for the E-alone subgroup but found no significant effects for the E + P subgroup. No significant effects were found in delayed testing., Conclusion: The dissociation we found for immediate list and story recall is similar to the pattern of results in our literature tabulation. Fuzzy-Trace Theory posits parallel verbatim and gist traces plus a meta-cognitive review which becomes more gist-biased with age. Our results suggest that: (1) estrogen increases gist bias, hastening the normal age-related decline of list recall but slowing the decline of story recall relative to placebo; (2) decay of the verbatim trace over time generally causes a shift to gist, thereby accounting for the absence of a delayed recall difference; and (3) progestin weakens the effects of estrogen, thereby accounting for why the dissociation found in E-alone was absent in the E + P subgroup.

Objective: This study examines the magnitude and direction of nonword and word lexical decision repetition priming effects in Alzheimer's disease (AD) and normal aging, focusing specifically on the negative priming effect sometimes observed with repeated nonwords., Method: Probable AD patients (30), elderly normal controls (34), and young normal controls (49) participated in a repetition priming experiment using low-frequency words and word-like nonwords with a letter-level orthographic orienting task at study followed by a lexical decision test phase., Results: Although participants' reaction times (RTs) were longer in AD compared with elderly normal, and elderly normal compared with young normal, the repetition priming effect and the degree to which the repetition priming effect was reversed for nonwords compared to words was unaffected by AD or normal aging., Conclusion: AD patients, like young and elderly normal participants, are able to modify (in the case of words) and create (in the case of nonwords) long-term memory traces for lexical stimuli, based on a single orthographic processing trial. The nonword repetition results are discussed from the perspective of new vocabulary learning commencing with a provisional lexical memory trace created after orthographic encoding of a novel word-like letter string., (PsycINFO Database Record (c) 2014 APA, all rights reserved.)

The primary purpose of this study was to determine the effect of one versus two encoding trials in the classical yes/no recognition memory paradigm using olfactory stimuli. A group of 24 young adults rated 18 standard microencapsulated odorant targets for familiarity (first encoding block) or pleasantness (second encoding block). Once-encoded targets were in only one block and twice-encoded targets were in both, with items counterbalanced across participants. Participants performed a 20-min nonverbal distractor task followed by a yes/no recognition test incorporating 18 additional odors as foils. Memory performance for twice-encoded targets was superior to that for once-encoded targets. For once-encoded targets, performance did not differ between those rated for familiarity versus those rated for pleasantness. Less pleasant odors produced overall better recognition, with a tendency for less familiar odors to produce overall better recognition. There was a tendency for the second encoding trial to have a larger effect for less pleasant or familiar odors than for more pleasant or familiar odors. The main conclusion is that recognition memory for odors is better for items encoded two times than for items encoded only once. Implications of these findings and suggestions for future research are discussed.

Introduction: This study addressed the relationship of both semantic priming and slowed lexical access to the symptoms of schizophrenia, and evaluated their association with other neurocognitive deficits., Methods: 57 outpatients with schizophrenia and 20 nonpsychiatric control subjects performed a lexical decision semantic priming task (LDT), and a brief neuropsychological battery. The schizophrenia group was also assessed with an extended Positive and Negative Symptom Scale., Results: As expected, the schizophrenia group had significantly slower reaction times (RTs) than the control group, and poorer performance on most neuropsychological tasks. Both groups exhibited semantic priming effects in both automatic and controlled processing conditions; these effects were not significantly different between groups. RT was unrelated to age, illness duration, GAF scores, or neuroleptic dose; controlled semantic priming effects were related to illness duration only. RT to real word targets (but not to nonwords) on the LDT was significantly correlated with positive and disorganised, but not negative symptoms. The neurocognitive correlates of RT slowing were: full-scale IQ and verbal fluency, but not attention; working memory; episodic memory retrieval; executive function, or manual speed. Both controlled semantic priming effects as well as the difference between controlled and automatic priming effects were related to executive functions in general. Severity of symptoms in the three major symptom groups was generally unassociated with impairment on the neuropsychological battery. The associations of RT slowing to positive and disorganised symptoms remained even after controlling for each of the above clinical and neurocognitive measures., Conclusions: These findings suggest that in schizophrenia, slowed lexical access is uniquely related to positive and disorganised symptoms. This relationship is not accounted for by more general cognitive deficits, overall illness severity, or generalised effects of symptoms on cognitive function. This relationship may reflect a specific impairment in the access to semantic memory.

G. Storms, T. Dirikx, J. Saerens, S. Verstaeten, and P. P. De Deyn (2003) have provided an important critique of the use of multidimensional scaling (MDS) to evaluate semantic knowledge in Alzheimer's disease. If MDS is to be used with semantic proximity data (in spite of well-documented reasons for not doing so), at minimum, the issues raised in G. Storms et al. should be considered. A few criticisms of the target article are presented. Then, the manner in which key points from the article, along with a consideration of such factors affecting proximity elicitation as semantic domains, tasks, and the experimental context, could be applied to correct certain shortcomings in the literature are discussed.

We systematically examined the relationship of both lexical retrieval and semantic memory organization to categorical verbal fluency performance in 40 outpatient schizophrenic subjects and 16 healthy controls. Mean choice reaction time (RT) on a lexical decision task was used as a measure of lexical retrieval efficiency. The complexity of semantic memory organization was measured using a Pathfinder semantic network analysis (calculated as the number of inter-node links obtained from a similarity rating task). In the schizophrenia group only, RT and semantic network links were each significantly negatively correlated with fluency and, together, accounted for 23% of the variance in fluency. RT and links were not significantly correlated with one another. Findings were unrelated to age, sex, education, or medication dose. Controlling for IQ reduced but did not abolish the relationship between fluency and network links. We conclude that the restricted verbal output of schizophrenic subjects is related both to impaired lexical retrieval and to variation in semantic memory organization, which partly reflects general intelligence. The statistical independence of the retrieval speed and organizational factors suggests that individuals with schizophrenia differ in the underlying processes that contribute to their reduced verbal fluency., (Copyright 2002 Elsevier Science B.V.)

This paper provides a critical review of RT and non-RT methodology for the conduct of research on semantic priming in Alzheimer's disease (AD) compared to elderly normal (EN) individuals. The review is organized by type of semantic priming (or attribute-knowledge) paradigm. Theoretical as well as methodological issues are highlighted insofar as they are relevant to: (1) the design, conduct, and analysis of semantic priming experiments (and closely related types of experiments) with AD compared to EN participants, and (2) the interpretation of findings from these experiments. Recommendations are provided for further research involving semantic priming and related paradigms with AD and certain other neuropsychological populations.

In this paper, we present a review of semantic priming experiments in schizophrenia. Semantic priming paradigms show utility in assessing the role of deficits in semantic memory network access in the pathology of schizophrenia. The studies are placed in the context of current models of information processing. In this review we include all English-language reports (from peer-reviewed journals) of single-word semantic priming studies involving participants with schizophrenia. The studies to date show schizophrenic patients to exhibit variable semantic priming effects under automatic processing conditions, and consistent impairments under controlled/attentional conditions. We also describe associations with other neurocognitive dysfunction, neurochemical and electrophysiological disturbances, and clinical manifestations (such as thought disorder).

Alzheimer's disease (AD) patients often exhibit deficits on conceptual implicit memory tests such as category exemplar generation and word association. However, these tests rely on word production abilities, which are known to be disrupted by AD. The current study assessed conceptual implicit memory performance in AD patients and elderly control participants using a conceptual priming task that did not require word production (i.e., semantic decision). Memory performance was also examined using a category exemplar generation test (i.e., a conceptual priming task that required word production) and a recognition memory test. AD patients exhibited deficits on the semantic decision task, the category exemplar generation task, and the recognition memory task. The results indicate that the conceptual memory deficits observed in AD patients cannot be attributed completely to word production difficulties.

We used a novel apparatus called the flags board to elicit similarity judgments from 32 Alzheimer's disease (AD) patients and 32 elderly normal (EN) controls for two 12-member conceptual domains, ANIMALS and (musical) INSTRUMENTS. Based on Pathfinder and multidimensional scaling (MDS) analyses, performance by AD patients was nearly identical to that of EN controls for ANIMALS. Performance differed for INSTRUMENTS, but the AD group's Pathfinder network was found to agree with the intuitions of a panel of 18 raters as well as the EN group's. MDS analysis showed no deficit on abstract dimensions for the AD group, for either domain. The results are discussed in the context of degradation versus preservation of semantic memory in AD.

Tip-of-the-tongue (TOT) experiences were examined in 30 young (ages 18-24 years), 30 young-old (ages 60-74), and 30 old-old (ages 80-92) adults. In Study 1, TOT experiences were experimentally induced with definitions of to-be-retrieved targets. If the target was not retrieved, orthographic or semantic cues were provided. Age-related increases in the occurrence of TOT experiences and in the time needed to resolve TOT experiences were found for young versus young-old and young-old versus old-old groups; all comparisons were significant except for young versus young-old TOT occurrence, which approached significance. In Study 2, the same participants recorded naturally occurring TOT experiences in structured diaries during a 4-week interval. Both the number of TOT experiences and the resolution time for TOT experiences increased with age. However, the percentage of TOT experiences resolved was equal across age groups; given enough time, even the oldest participants resolved virtually all TOT experiences.

This study examined whether frontal-system impairments in schizophrenia occur independently of one another and whether they have distinct implications for information processing, symptom severity, and adaptive functioning. We assessed 26 medication-free schizophrenic outpatients and 18 normal control subjects on eight frontally mediated tasks, semantic information processing, IQ, the BPRS, and long-term psychosocial adaptation. Schizophrenic subjects showed three types of deficits, which were uncorrelated with one another: (1) Executive dysfunction (inflexible problem solving) was related to decreased use of expectancy during controlled semantic priming, lower intelligence, more severe negative symptoms and stereotyped mannerisms. (2) Disinhibition of responses (to irrelevant stimuli) was associated with increased automatic priming, a trend for more severe hallucinations, and was unrelated to intelligence. (3) Motor dyscoordination (inaccurate, dysfluent motor sequencing) was not related to semantic processing, intelligence, or symptoms. Furthermore, all three impairments were unrelated to generalized slowness, age, sex, illness length, or pre-washout neuroleptic dose. Two deficits accounted for aspects of long-term psychosocial adaptation, even after statistical correction for IQ: Executive dysfunction was associated with younger illness onset, poor purposefulness and planning, impaired social relations, and lower global functioning. Motor dyscoordination was associated with poor treatment outcome and restricted educational advancement. Furthermore, executive and motor deficits interacted significantly; subjects who had both deficits showed the least favorable treatment outcome. These findings are neither consistent with generalized impairment nor with a unitary 'frontal syndrome' in schizophrenia. They provide preliminary evidence for at least three frontal-system deficits (dorsolateral, orbital, and premotor), which are dissociable from one another, can occur without general intellectual impairment, and have distinct implications for long-term adaptive functioning.

Extensive research has demonstrated that schizophrenic subjects are slower than normal comparison subjects on a range of reaction-time tasks. Some investigators have also observed that schizophrenic patients exhibit larger intraindividual variability in reaction times when performing these tasks than do normal comparison subjects. This study, using a lexical decision choice reaction time (CRT) task, explored the relation of mean CRT and it intra-individual variability (CRT-SD) to psychiatric symptoms and to performance on executive-motor tasks in 26 medication-free schizophrenic out-patients and 17 normal comparison subjects. Schizophrenic subjects had both significantly slower and more variable CRTs which were unrelated to general intellectual abilities (IQ). Among schizophrenic subjects, both CRT and CRT-SD were significantly related to severity of psychotic symptoms, failure to maintain cognitive set, and poorer motor coordination and global functioning. After controlling for mean CRT, CRT-SD showed unique covariation with clinical symptoms (positive, disorganized and tension/hostility). Conversely, mean CRT showed unique covariation with the failure to maintain cognitive set and with stereotypic mannerisms, independent of CRT-SD. These results suggest that slower CRT and increased intra-individual variability in CRT, while not fully independent of one another, may reflect separate aspects of symptomatic and cognitive dysfunction in schizophrenia.

Predictors of perceived memory impairment were investigated in 40 elderly normal adults and 28 individuals with Alzheimer's disease. Measures of perceived memory impairment, global cognitive functioning, memory, use of memory strategies, memory strategy efficacy, and depressive symptomatology were obtained for all participants. The elderly normal and Alzheimer's disease groups did not differ in the extent to which they reported perceived memory impairment. For both participant groups, more frequent use of memory strategies and lower perceived memory strategy efficacy were significant predictors of perceived memory impairment. Depressive symptomatology was an additional, significant determinant of perceived memory impairment for the elderly normal group.

Objective: Source monitoring, an aspect of memory that involves judgments about the origin of information, has been found to be more prone to errors in schizophrenic subjects than in normal persons. To examine the precise nature of such errors and their relationship to clinical and neurocognitive variables, the authors compared schizophrenic and normal subjects., Method: Schizophrenic subjects who had been medication free for 1 week (N = 26) and demographically matched normal subjects (N = 21) performed a source monitoring task and were assessed on current psychiatric symptoms, IQ, and frontal lobe functioning., Results: The schizophrenic subjects had normal recognition memory of target words (recognition hits) and a normal generation effect but made more errors than the comparison subjects in identifying the source of target words. Specifically, the schizophrenic subjects made more errors in remembering the source of new and self-generated items, and they tended to attribute items to an external source. In 11 retested subjects, these errors were stable and independent from medication status after a 2-year interval. Secondary analyses suggested that certain source monitoring errors may be associated with hostility and lower IQ. When the effect of IQ was controlled, correlations with frontal dysfunction were not significant., Conclusions: Schizophrenic subjects make significantly more source monitoring errors than normal subjects, but not because of problems with recognition memory hits or with the generation effect. This tendency may be trait like and may be related to hostility. Lower IQ in schizophrenia plays a partial role in these errors, but frontal dysfunction does not.

Schizophrenic individuals (n = 31), including paranoid and nonparanoid diagnostic subgroups, and normal controls (n = 20) participated in a semantic priming experiment involving a single-choice lexical decision task. For the automatic priming blocks, a 260-ms stimulus onset asynchrony (SOA) was used; for the controlled priming blocks, 1,000-ms SOA was used. The paranoid subgroup showed significantly less priming than did the control group. The nonparanoid subgroup showed a decrease in priming compared with the control group that approached significance. There was an increased priming effect for the controlled compared with the automatic priming condition; this difference was not modulated by participant group. Nonsignificant semantic priming (equal to 0) occurred only for schizophrenic subgroups and only in automatic priming conditions.

We conducted a lexical-decision, semantic priming experiment that included 250- and 1000-ms stimulus onset asynchronies (SOAs) with 32 probable Alzheimer's disease (AD) and 40 older normal persons. Attention-based, controlled processes are assumed to occur only at the longer of the 2 SOAs. The AD group showed greater than normal priming in the long-SOA but not the short-SOA condition. We conclude that greater than normal AD priming is a function of controlled processing rather than semantic network degradation.

A 58-year-old man developed progressive difficulty with comprehension and verbal output with dementia. Positron emission tomography with 18F 2-fluoro-2-deoxy-D-glucose demonstrated asymmetrical frontal and anterior temporal lobe loss of glucose use. Scopolamine infusion (0.3 mg) did not influence memory. Postmortem studies revealed evidence of Pick's disease, with Pick bodies, loss of somatostatin, preservation of choline acetyltransferase and immunostaining with neurofilament antibodies. Pharmacological challenge and positron imaging offer valuable means for the noninvasive assessment of dementing illness. The contributions of functional imaging to our knowledge of frontal involvement in dementing illness are reviewed.

Experimental assessments of semantic memory structure and function in schizophrenic subjects can be a useful approach for delineating some of the information processing deficits in schizophrenia. In this study, a pronunciation and a lexical decision semantic priming experiment were conducted with 19 schizophrenic subjects and 20 normal controls. A short stimulus-onset asynchrony (250 msec) and a relatively low proportion of related prime-target pairs were used in order to examine automatic priming and in order to avoid the contribution of attentional, controlled processes. On the pronunciation task, schizophrenic subjects showed a significant priming effect, equal to the priming shown by normal controls. However, on the lexical decision task, schizophrenics, unlike normal controls, did not show a priming effect which is significantly greater than zero, even though the group difference in priming effect (interaction of priming effect by group) was nonsignificant. The lack of priming on the lexical decision task is consistent with the hypothesis that schizophrenic subjects may show abnormalities in the realm of post-lexical, controlled information processing. The equal-to-normal priming for schizophrenic subjects indicates that the basic structure of the semantic network, including associations among related concepts, is intact in schizophrenia, and that spreading activation also occurs normally.

The 6 experiments reported here tested the effects of various category relations on automatic semantic priming in 20 Alzheimer's disease (AD), 20 older control, and 22 younger control subjects. The tasks were either word pronunciation or lexical decision; the prime-target stimulus-onset asynchrony (SOA) was always 250 ms. A variety of category relationships between prime and target were examined: highly associated category comembers, subordinate-superordinate or superordinate-subordinate pairs, and pairs selected on the basis of category typically to form typical-typical, atypical-typical, typical-atypical, and atypical-atypical pairings. Both for AD versus older control subjects and for older versus younger control subjects, no significant group differences were found in the magnitude of overall semantic priming or in the effects on priming of factors pertaining to the prime-target relationship.

The drawings of Alzheimer's disease (AD) patients and elderly control subjects were rated on a number of specific performance scales, such as attention to configuration, attention to detail, and stimulus boundedness. AD patients showed significantly poorer performance than controls on most drawing scales, and the drawing measures were differentially affected by disease severity. Regional cerebral glucose metabolism (rCMRglc) was assessed via positron emission tomography (PET, with 18FDG) in a subgroup of the AD patients. Partial correlations of rCMRglc with drawing measures (age, sex, and education served as control variables) were conducted. Five out of eight of the drawing measures were significantly correlated (p less than .005) with rCMRglc in occipital and/or temporal-parietal regions, for both left and right hemispheres. Only one of the eight drawing measures, attention to detail, was significantly correlated with rCMRglc in both frontal and posterior regions of interest, again for both hemispheres. Overall dementia severity showed no significant correlations with rCMRglc in any of the regions. These findings are suggestive of a posterior-anterior differentiation, but no left-right hemisphere differentiation, in the relationship between drawing performance and cerebral metabolism in AD, which cannot be accounted for by overall dementia severity. Differences between the drawing performance of AD and unilateral brain damaged patients are discussed, and further applications of the rating scales (provided in the Appendix) are suggested.

Horizontal eye-movement responses of four patients with Alzheimer-type dementia were recorded using the infrared oculographic technique. Abnormally frequent saccadic intrusions occurred during the fixation and slow, smooth pursuit tasks in all four patients. Saccadic intrusions have previously been reported in the literature to occur in normals, in strabismus, in patients with certain neurological disorders, and in schizophrenic patients. This is the first report of a group of Alzheimer-type dements with an eye movement abnormality which cannot be regarded as an ocularmotor reflection of diffuse cerebral dysfunction.

The Stroop color-word test was used to examine patterns of cognitive decline in Alzheimer-type dementia (ATD) and non-Alzheimer dementia. Slowing on color naming and word reading was observed, and was greater in moderate than in mild dementia subjects. However, error scores were unrelated to dementia type and severity. The Stroop interference effect, measured with reaction time, was high in individuals with mild ATD and mild non-Alzheimer dementia. In contrast, the more severely impaired ATD subjects showed less Stroop interference effect than mildly impaired subjects when the reaction time was adjusted for color naming performance. These findings are attributed to variation in speed-accuracy tradeoff for the patient groups due to differences in information processing deficits, linguistic impairment, and attitudes to errors. This study demonstrates the importance of partialling out underlying deficits for the understanding of complex cognitive processes in dementia.

Patients with probable Alzheimer's disease (AD) were no faster at making lexical decisions to targets preceded by a semantic prime than to those preceded by an unrelated prime, in contrast to the facilitatory effect of semantic primes for controls. Fewer errors were made by both subject groups on the targets that followed related items, indicating the preservation of associative relationships in AD. The AD patients and controls showed similar effects on lexical decision of repetition priming, word frequency, and the degree to which nonwords approximated real words. The abnormal priming effect in AD may stem from increased susceptibility to lateral inhibition in the semantic network.

We performed SPECT perfusion imaging and memory testing with mildly and moderately demented Alzheimer's disease (AD) patients and with healthy controls. All patients had memory abnormalities, but 5 of the 21 patients had neither temporal nor parietal perfusion abnormalities, indicating that temporoparietal blood flow may be normal at a point when memory is pathologic and the clinical diagnosis of AD is possible.

Alzheimer disease is the most common cause of dementia in adults. Despite recent advances in our understanding of its anatomy and chemistry, we remain largely ignorant of its pathogenesis, physiology, diagnosis, and treatment. Dynamic positron emission tomography using [18F]fluorodeoxyglucose (FDG) was performed on the Donner 280-crystal ring in 10 subjects with dementia of the Alzheimer type and six healthy age-matched controls. Ratios comparing mean counts per resolution element in frontal, temporoparietal, and entire cortex regions in brain sections 10 mm thick obtained 40-70 min following FDG injection showed relatively less FDG uptake in the temporoparietal cortex bilaterally in all the Alzheimer subjects (p less than 0.01). Left-right alterations were less prominent than the anteroposterior changes. This diminished uptake was due to lowered rates of FDG use and suggests that the metabolic effects of Alzheimer disease are most concentrated in the temporoparietal cortex. Positron emission tomography is a most powerful tool for the noninvasive in vivo assessment of cerebral pathophysiology in dementia.

Retrieval from semantic memory, measured by tasks requiring subjects to name items from a given category, was studied in mild Alzheimer-type dementia (Mild-ATD) subjects, moderate-to-severe Alzheimer-type dementia (MS-ATD) subjects, and normal controls. Semantic retrieval performance was shown to be highly sensitive to both the presence and the severity of ATD. Retrieval from both semantic categories and letter categories showed differences in the rate of production of correct responses between subject groups. These rate differences were not due to differences in accessibility of low-dominance semantic category members or low-frequency letter category members. An increase in errors as well as a decrease in correct responses contributed to the performance deficits of the ATD subjects. Furthermore, the pattern of errors changed from Mild- to MS-ATD. Qualitative as well as quantitative differences were also observed in the performance of Mild- versus MS-ATD groups on a third type of semantic retrieval task--the supermarket task. As performance of the ATD subjects declined on these semantic retrieval tasks, so did their performance on other tasks assessing primarily attention, language, and memory. The findings are discussed in terms of the progressive breakdown in both attentional and semantic memory functions which are associated with ATD.

Positron emission tomography with [18F]fluorodeoxyglucose revealed greater right than left hemispheric impairment of cortical glucose metabolism in patients with probable Alzheimer's disease who were younger than 65 but not in those over 65. This asymmetry was related to poor visuospatial performance.

Alcoholics and controls were compared on their resistance to misleading information given after a witnessed event. The eyewitness testimony paradigm of Loftus, Miller, and Burns ("Semantic Integration of Verbal Information in a Visual Memory" Journal of Experimental Psychology: Human Learning and Memory, Vol. 4, pp. 19-31, 1978) was used, which is a naturalistic variation of a retroactive interference paradigm. Alcoholics did not show greater suggestibility than the controls, being no more "fooled" by the misleading, after-the-fact information. In contrast, alcoholics did show significant impairment in discriminating correct from among incorrect verbal statements about the accident. Thus, certain aspects of memory functioning may be preserved even while others are compromised as a result of chronic alcohol abuse.

Multiple aspects of verbal learning and memory performance in mild as compared to moderate Alzheimer-type dementia (ATD) were studied with the Buschke selective reminding paradigm. Results show that (1) both groups of ATD subjects depend less on long-term memory (LTM) and more on short-term memory (STM) relative to elderly control subjects, (2) mild ATD subjects show less LTM encoding than moderate ATD subjects, (3) moderate ATD subjects retrieve a smaller portion of the items presumed to be encoded into LTM than do mild ATD subjects, and (4) high-imagery words increase LTM encoding and retrieval as compared to low-imagery words for moderate ATD subjects only. These results are explained by the inability of ATD subjects to attend to more than one component of the list-learning task, in conjunction with differences in the deployment of attention between mild and moderate ATD subjects.

We performed dynamic positron emission tomographic studies with [18F]fluorodeoxyglucose in 17 subjects with presumed Alzheimer's disease (AD) and 7 healthy aged subjects. Glucose metabolism was depressed by 27% in temporal-parietal cortex of the AD group, as compared to healthy aged controls. This focal impairment in temporal-parietal glucose use was found in all AD subjects. In addition, the AD group showed a striking lateral asymmetry of cortical metabolism not favoring either hemisphere, which has not been previously reported. Relationships between these focal changes and behavioral features of the illness were demonstrated. These results have important implications for the diagnosis and perhaps the etiology of Alzheimer's disease.

We performed dynamic positron emission tomographic (PET) studies of glucose utilization, using (18F) 2-fluoro-2-deoxy-D-glucose (FDG), in patients with probable Alzheimer's disease (AD) and healthy age-matched controls, to evaluate blood-brain-barrier glucose transport and glucose utilization rates in the disease. We found no significant differences in rate constants for glucose transport (k1 and k2) and phosphorylation (k3), nor for the vascular fraction (fv), between the 2 groups, although k3 and fv were relatively depressed in temporal cortex in AD. Absolute rates of glucose use were depressed in temporal and parietal cortex, and relative rCMRglc rates were lower in frontal, temporal, parietal, and occipital cortices. These data suggest that in AD bidirectional glucose transport is intact, and that temporal-parietal hypometabolism is present upon a background of widespread cortical metabolic impairment.