Intact Memory Function Research Articles

Nicht jede Hirnleistungsschwäche ist demenzbedingt.

A 55 years old woman lived with the parents until they died. Recently, she refused to open her apartment for necessary repairs. An examination was possible only after police opened the apartment. She is in excellent physical health, has intact memory functions but reduced executive abilities. She has no delusion, but excessive fear from strangers as taught by her parents. The clinical impression of a debility is confirmed by enquiry at her relatives. The installation of a guardianship can give the necessary support for daily life.

A multi-center, randomized, double blind placebo-controlled trial of estrogens to prevent Alzheimer's disease and loss of memory in women: design and baseline characteristics.

Observational studies and small clinical trials suggested that hormone replacement therapy (HRT) decreases risk of cognitive loss and Alzheimer's disease (AD) in postmenopausal women and may have value in primary prevention. A clinical trial was designed to determine if HRT delays AD or memory loss. This report describes the rationale and original design of the trial and details extensive modifications that were required to respond to unanticipated findings that emerged from other studies during the course of the trial. The trial was designed as a multi-center, placebo-controlled primary prevention trial for women 65 years of age or older with a family history of dementia. Recruitment from local sites was supplemented by centralized efforts to use names of Medicare beneficiaries. Inclusion criteria included good general health and intact memory functioning. Participants were randomized to HRT or placebo in a 1:1 ratio. Assignment was stratified by hysterectomy status and site. The primary outcomes were incident AD and memory decline on neuropsychological testing. Enrollment began in March 1998. In response to the Women's Health Initiative (WHI) May 2002 report of increased incidence of heart disease, stroke, pulmonary embolism, and breast cancer among women randomized to HRT, participants were re-consented with a revised consent form. Procedural modifications, including discontinuation of study medication and a modification of the planned primary outcome based on a final enrollment below the target enrollment (N = 477), were enacted in response to the subsequent WHI Memory Study report of increased risk of dementia and poorer cognitive function with HRT. The mean length of treatment exposure prior to discontinuation was 2.14 years. Participants' mean age at baseline was 72.8; mean education was 14.2 years. Minority participation was 19% and 34% had a hysterectomy. The study continues to follow these participants for a total of 5 years blind to the original medication assignment. Results reported from the WHI during the course of this study mandated extensive procedural modifications, including discontinuing recruitment before completion and halting study medication. Alternative strategies for study redesign that were considered are discussed.

Hippocampal function during associative learning in patients with posttraumatic stress disorder

In the last decade several studies have shown memory deficits in patients with posttraumatic stress disorder (PTSD) which have been associated with a reduced hippocampus volume. However, until now we do not know how or whether these structural abnormalities turn into functional abnormalities. Thus, the primary purpose of the present study was the investigation of the hippocampal function using functional magnet resonance imaging (fMRI). We compared PTSD patients and healthy control participants using an associative learning paradigm consisting of two encoding and one retrieval condition. During fMRI scanning participants had to learn face-profession pairs. Afterwards only faces were presented as cue stimuli for associating the category of the prior learned target profession and the participants had to decide whether this face belonged to a scientific or an artistic profession. Additionally, cognitive functioning, i.e. memory and attention, was examined using neuropsychological standard tests. During encoding PTSD patients showed stronger hippocampal and weaker prefrontal activation compared to healthy control participants. During retrieval the two groups did not differ neither in hippocampus activation nor in accuracy of retrieval. PTSD patients however showed a reduced activation in the left parahippocampal gyrus and other memory-related brain regions. We did not find any significant memory differences between PTSD patients and healthy control participants. The results suggest that PTSD has an effect on memory-related brain function despite intact memory functioning. In particular the hippocampal/parahippocampal regions and the prefrontal cortex show functional alterations during associative learning and memory.

Impact of memory impairment on employment status in persons with systemic lupus erythematosus

To assess the specific contribution of memory impairment to employment status in persons with systemic lupus erythematosus (SLE). A total of 832 patients with SLE were surveyed and data collected on demographics, SLE symptoms and activity, health status, depression, medications, health resource utilization, and current employment status. Participants underwent screening for memory impairment and based on their scores were categorized to 3 levels of memory function: intact, mild-moderate impairment, and severe impairment. Employment status was compared across impairment levels using multivariate logistic regression, adjusting for sociodemographic characteristics (i.e., age, sex, race, education, and marital status), employment status at year of diagnosis, disease activity, disease duration, and depression. In the intact memory function group, 54.2% were employed, versus 40.6% in the mild-moderate impairment group and 31.0% in the severe impairment group. In the intact memory function group, 29.2% were unable to work, versus 40.6% in the mild-moderate impairment group and 56.3% in the severe impairment group. After multivariate adjustment, increasing levels of memory impairment predicted a decreased likelihood of being employed: odds ratio (OR) 0.70, 95% confidence interval (95% CI) 0.48-1.02 for the mild-moderate impairment group and OR 0.57, 95% CI 0.32-1.00 for the severe impairment group. Participants with memory impairment were more likely to report being unable to work: OR 1.36, 95% CI 0.90-2.04 for the mild-moderate impairment group, and OR 1.99, 95% CI 1.12-3.55 for the severe impairment group. These findings were statistically significant only in the severe impairment groups. The findings suggest that severe memory impairment is an important factor associated with employment status in persons with SLE.

Plaque-bearing mice with reduced levels of oligomeric amyloid-β assemblies have intact memory function

The amyloid-β (Aβ) protein exists in the aging mammalian brain in diverse assembly states, including amyloid plaques and soluble Aβ oligomers. Both forms of Aβ have been shown to impair neuronal function, but their precise roles in Alzheimer's disease (AD) –associated memory loss remain unclear. Both types of Aβ are usually present at the same time in the brain, which has made it difficult to evaluate the effects of plaques and oligomers individually on memory function. Recently, a particular oligomeric Aβ assembly, Aβ*56, was found to impair memory function in the absence of amyloid plaques. Until now it has not been possible to determine the effects of plaques, in the absence of Aβ oligomers, on memory function. We have identified Tg2576 mice with plaques but markedly reduced levels of Aβ oligomers, which enabled us to study the effects of plaques alone on memory function. We found that animals with amyloid plaques have normal memory function throughout an episode of reduced Aβ oligomers, which occurs during a period of accelerated amyloid plaque formation. These observations support the importance of Aβ oligomers in memory loss and indicate that, at least initially, amyloid plaques do not impair memory.

The Localization and Lateralization of Memory Deficits in Children with Temporal Lobe Epilepsy

It is often reported that children with temporal lobe epilepsy (TLE) experience nonlateralized memory impairments. However, many of these studies have been exploratory and not based on memory theory. Further, differences between mesial and lateral subgroups have not been adequately examined. This study aimed to discern more specific patterns of memory impairment in children with TLE. Forty-three children (5-16 years) with lesional TLE participated. Subjects were categorized in terms of lesion laterality (left, n = 21; right, n = 22) and intratemporal location (mesial, n = 31; lateral, n = 12). Verbal and nonverbal memory tasks were administered that reflected associative, allocentric and recognition paradigms. Facial recognition was poorer in right TLE (p = 0.03). There were no differences between left and right groups on any other memory task, even when comparisons were restricted to cases with mesial involvement. Irrespective of laterality, clear differences were observed between mesial and lateral lesion subgroups (arbitrary associative learning, p = 0.01; complex figure recall, p = 0.03). The lateral lesion subgroup displayed intact memory function relative to normative standards. Memory is more frequently impaired in children with mesial as opposed to lateral TLE. Tasks with an associative component discriminated between these subgroups, supporting an associative model of hippocampal function. With the exception of facial recognition, memory deficits were not lateralized. Therefore, the nature of memory impairment experienced by children with TLE cannot be extrapolated from adult models.

Effects of errorless and errorful face-name associative learning in moderate to severe dementia

The prevention of errors during learning has been found to be effective in overcoming memory problems in patients with amnesia compared with errorful or trial-and-error learning, possibly as a result of intact implicit memory function. Although errorless learning is a clinically promising technique used in cognitive training settings, to date only a few studies have examined errorless learning in patients with dementia. The current study examined errorless and errorful learning using a face-name associative memory task in a group of moderate to severe dementia patients suffering from probable Alzheimer's disease (MMSE < or = 22; n = 10) using a fully counterbalanced within-subject design. Errorless learning had a significantly beneficial effect after two consecutive learning trials (p = 0.01). However, after an unfilled delay of 10 minutes, no significant differences in memory performance were found between errorless and errorful learning. Furthermore, current effects were much smaller compared with previous findings in healthy adults and early-stage dementia patients. Although errorful learning resulted in better performance in a face-name associative memory task in patients with dementia, this effect was only short-lived. Thus, the beneficial effects of errorless learning are probably not due to intact implicit memory function, but may also be subserved by explicit memory, a memory system that is typically impaired in dementia. Also, the clinical applicability of errorless learning in teaching patients with moderate to severe dementia face-name associations is limited.

Implicit and Explicit Memory for Spatial Information in Alzheimer’s Disease

There is abundant evidence that memory impairment in dementia in patients with Alzheimer’s disease (AD) is related to explicit, conscious forms of memory, whereas implicit, unconscious forms of memory function remain relatively intact or are less severely affected. Only a few studies have been performed on spatial memory function in AD, showing that AD patients’ explicit spatial memory is impaired, possibly related to hippocampal dysfunction. However, studies on implicit spatial memory in AD are lacking. The current study set out to investigate implicit and explicit spatial memory in AD patients (n = 18) using an ecologically valid computer task, in which participants had to remember the locations of various objects in common rooms. The contribution of implicit and explicit memory functions was estimated by means of the process dissociation procedure. The results show that explicit spatial memory is impaired in AD patients compared with a control group (n = 21). However, no group difference was found on implicit spatial function. This indicates that spared implicit memory in AD extends to the spatial domain, while the explicit spatial memory function deteriorates. Clinically, this finding might be relevant, in that an intact implicit memory function might be helpful in overcoming problems in explicit processing.

Reduced hippocampal volume among adolescents with alcohol use disorders without psychiatric comorbidity

Studies have suggested that teens with alcohol use disorder (AUD) can demonstrate memory deficits, but the underlying neuroanatomical substrates are unclear. The hippocampus is crucial to intact memory functioning, and it actively develops during adolescence. The current study attempted to replicate and extend previous findings suggesting that adolescents with AUD show smaller hippocampal volumes than healthy adolescents. Manual tracings of bilateral hippocampi were performed on structural magnetic resonance images of 14 adolescents (ages 15 to 17 years) with AUD and 17 healthy comparison teens. Intracranial, white, and gray matter volumes, as well as memory abilities, were also measured. Results revealed that adolescents with AUD had significantly smaller left hippocampal volumes than healthy teens, even after removal of teens with comorbid conduct disorder from the analyses. In contrast the groups did not differ in right hippocampal, intracranial, gray or white matter volumes, or memory performance. Hippocampal volumes were not related to alcohol-consumption rates. These findings indicate that adolescents with AUD, but free from other psychiatric comorbidities, have reduced left hippocampal volume. Because hippocampal volume did not relate to alcohol use characteristics, it is possible that premorbid volumetric differences could account for some of the observed group differences in hippocampal volume.

The pattern of intact and impaired memory functions in autism.

A battery of tests of auditory and visual memory was used to investigate memory function in 52 high-functioning adolescents and young adults with autism and 40 group-matched normal controls. It was hypothesized that memory dysfunction is present in autism but is not modality specific and is produced by poor utilization of organizing strategies. It was therefore hypothesized that memory impairment in autism would become more prominent as task complexity was increased. The participants with autism performed as well as controls on short-term memory and paired-associate learning tasks, but performed significantly less well than controls on a list learning task. They also performed significantly more poorly on immediate and delayed recall of a story and of a complex geometric figure. On a maze learning task, their performance became progressively worse relative to controls as the complexity of the maze increased. On a series of span tasks, they did not differ from controls on letter span, but did significantly worse on word span and sentences of increasing complexity. These findings indicate a lack of modality specificity and a failure to initiate organizing strategies as evidenced by inefficiency in new learning, poor utilization of contextual cues in story and complex pattern recall, and greater impairment with increasing complexity of the material.

Pathological Changes in the Parahippocampal Region in Select Non‐Alzheimer's Dementias

The transentorhinal and entorhinal regions of the human brain extend over the ambient gyrus and anterior portions of the parahippocampal gyrus. They are important components of the limbic loop which receives its major afferents from the neocortical sensory association areas and generates powerful efferent projections both directly and via intermediary relay stations to the prefrontal cortex. The bilateral structural preservation of limbic loop components is a prerequisite for the maintenance of intact memory functions. In progressive neurodegenerative diseases, such as Alzheimer's disease, argyrophilic grain disease, Pick's disease, idiopathic Parkinson syndrome, and Huntington's disease, the transentorhinal and entorhinal regions are particularly susceptible to severe pathological changes. The transentorhinal region typically registers the initial alterations and becomes the most severely involved. From this transitional region of the mesocortex, the alterations usually invade with decreasing severity both the entorhinal region and temporal proneocortex. Each type of lesion that develops in the above-mentioned neurodegenerative disorders hampers or even interrupts data-transport from the sensory neocortex to the prefrontal neocortex, thereby contributing to the insidious development of progressive changes in personality, cognitive decline, and, ultimately, dementia.

Intact and Impaired Memory Functions in Autism

This study examined memory functions in individuals with autism. Based on previous evidence of executive function (EF) deficits, we hypothesized that subjects with autism would demonstrate a pattern of intact and impaired memory functions similar to that found in other groups with EF deficits, such as patients with frontal lobe pathology. We compared the performance of high-functioning children and adolescents with autism (n = 19) and clinical comparison subjects (n = 19) matched on sex, CA, and VIQ on measures of memory and EF. The group with autism performed significantly worse than comparison subjects on measures of temporal order memory, source memory, supraspan free recall, working memory, and EF, but not on short- and long-term recognition, cued recall, or new learning ability, consistent with the predictions of the EF theory. The cognitive measures were significantly more intercorrelated in the autism group than the comparison group, consistent with a limit in central cognition.

Intact and Impaired Memory Functions in Autism

Intact and Impaired Memory Functions in Autism

The Possible Contribution of the Amygdala to Memory

The processing of episodic memories is believed to depend on the proper functioning of so-called bottleneck structures through which information apparently must pass in order to be stored long term. These regions are seen in the basal forebrain, the medial diencephalon, and the medial temporal lobe. We here report a case with circumscribed bilateral temporal lobe damage, principally involving the amygdaloid area. Neuropsychological investigation demonstrated preserved intelligence, intact general memory and several other undisturbed cognitive functions, but a specific, affect-related, memory disorder. We conclude from these findings that the role of the amygdala is to process mnemonic events in a way that a specific emotional significance can be found and reactivated. Therefore it is suggested that the amygdala is likely to be a bottleneck structure for affect-related long-term memory functions.

The possible contribution of the amygdala to memory.

The processing of episodic memories is believed to depend on the proper functioning of so-called bottleneck structures through which information apparently must pass in order to be stored long term. These regions are seen in the basal forebrain, the medial diencephalon, and the medial temporal lobe. We here report a case with circumscribed bilateral temporal lobe damage, principally involving the amygdaloid area. Neuropsychological investigation demonstrated preserved intelligence, intact general memory and several other undisturbed cognitive functions, but a specific, affect-related, memory disorder. We conclude from these findings that the role of the amygdala is to process mnemonic events in a way that a specific emotional significance can be found and reactivated. Therefore it is suggested that the amygdala is likely to be a bottleneck structure for affect-related long-term memory functions.

Thalamic Amnesia: Clinical and Experimental Aspects

One of the most interesting and important aspects of human behavior involves learning and memory. There is no question that clinical disorders of memory not only provide syndromes that are of significant theoretical interest, but also constitute, in some patients, a source of marked disability. The alcoholic Korsakoff syndrome, for example, constitutes a clinical problem of significant magnitude. In this regard, information about the neural basis for memory, derived from clinical or experimental observations, is of considerable importance. It is the purpose of this chapter to summarize the available evidence concerning one particular type of memory disorder that has a discrete neuro-anatomical substrate—that is, thalamic amnesia. Recognition of this syndrome is of obvious clinical importance because it can occur as a result of disorders—for example, neoplasm, infarction, hemorrhage—that require prompt and accurate diagnosis and treatment. This disorder also, however, has theoretical importance in pointing toward some of the central nervous system (CNS) structures that are required for intact memory function in mammals. Previous studies on the effects of focal lesions on memory have suggested the involvement of a number of structures. These include the hippocampus, temporal lobe, temporal stem, fornix, and cerebellar nuclei. There is evidence implicating each of these areas in memory function within the mammalian brain. This chapter discusses another nuclear area, the mediodorsal thalamus, which may play a role in memory and describes the amnestic deficits that may occur as a result of relatively discrete lesions of this diencephalic region.

Validity and diagnostic accuracy of an alternate form of the rey auditory verbal learning test

The diagnostic validity of an alternate form of the Rey Auditory Verbal Learning Test (AVLT) is investigated. Subjects were 73 inpatients from a VA Medical Center who were classified as having either intact ( n = 41) or impaired ( n = 32) memory functions. Employing a counterbalanced design, both groups were administered the standard (Form A) and alternate (Form C) forms of the AVLT. Means for the learning trials, trial VI and the recognition procedure were calculated for the intact and memory-impaired subjects and contrasted for each test. Results suggested that Form C discriminated groups at a level comparable to that of Form A. This impression was confirmed by separate stepwise discriminant analyses for Form A and Form C that yielded identical hit-rates (i.e., 75.3%) in terms of identifying subjects as memory-intact or memory-impaired. These findings suggested that Form C may be used for the assessment of persons with verbal mnemonic deficits with the same degree of confidence that has been attributed to Form A.

A Cognitive approach to Korsakoff's Syndrome

Ten Korsakoff and ten alcoholic subjects were compared on their ability to take advantage of meaningful and linguistic factors in five verbal memory experiments. Korsakoff subjects were deficient in the use of visual imagery, in remembering random letters and in learning relatively easy paired-associates; there was a suggestion that they did not benefit from variation in word class. The effect of word frequency, the ability to remember very easy paired-associates, and possibly the effect of pronounceability were preserved. These findings were interpreted as supporting a model which emphasised the disruption of some higher cognitive structure whilst leaving intact simpler memory functions.