Recognition Memory, Self-Other Source Memory, and Theory-of-Mind in Children with Autism Spectrum Disorder

This study investigated semantic and episodic memory in autism spectrum disorder (ASD), using a task which assessed recognition and self-other source memory. Children with ASD showed undiminished recognition memory but significantly diminished source memory, relative to age- and verbal ability-matched comparison children. Both children with and without ASD showed an “enactment effect”, demonstrating significantly better recognition and source memory for self-performed actions than other-person-performed actions. Within the comparison group, theory-of-mind (ToM) task performance was significantly correlated with source memory, specifically for other-person-performed actions (after statistically controlling for verbal ability). Within the ASD group, ToM task performance was not significantly correlated with source memory (after controlling for verbal ability). Possible explanations for these relations between source memory and ToM are considered.

Patterns of Autobiographical Memory in Adults with Autism Spectrum Disorder

Two studies are presented that explored the effects of experimental manipulations on the quality and accessibility of autobiographical memories in adults with autism spectrum disorder (ASD), relative to a typical comparison group matched for age, gender and IQ. Both studies found that the adults with ASD generated fewer specific memories than the comparison group, and took significantly longer to do so. Despite this, experimental manipulations affected two indices of autobiographical memory (specificity and retrieval latency) similarly in both groups. These results suggest that adults with ASD experience a quantitative reduction in the speed and specificity of autobiographical memory retrieval, but that when they do retrieve these memories, they do so in a way that is qualitatively similar to that of typical adults.     

Episodic memories

An account of episodic memories is developed that focuses on the types of knowledge they represent, their properties, and the functions they might serve. It is proposed that episodic memories consist of episodic elements, summary records of experience often in the form of visual images, associated to a conceptual frame that provides a conceptual context. Episodic memories are embedded in a more complex conceptual system in which they can become the basis of autobiographical memories. However, the function of episodic memories is to keep a record of progress with short-term goals and access to most episodic memories is lost soon after their formation. Finally, it is suggested that developmentally episodic memories form the basis of the conceptual system and it is from sets of episodic memories that early non-verbal conceptual knowledge is abstracted.     

Episodic simulation of future events is impaired in patients with major depressive disorder

We examined future episodic simulation in patients with major depressive disorder (MDD) using a method that distinguishes between episodic and non-episodic details of events. Patients were impaired at generating specific episodic details concerning future events; non-episodic details were not affected. In addition, all participants generated more episodic details for positive than for negative stimulus words. These results suggest a deficit in autonoetic awareness among patients with MDD. Difficulties imagining future events may impact upon the success of therapeutic interventions aimed at altering biases in the prediction of positive and negative future happenings.     

Brief Report: Self-defining and Everyday Autobiographical Memories in Adults with Autism Spectrum Disorders

Autobiographical memory impairments in autism spectrum disorders (ASD) have been attributed to a failure in using the self as an effective memory organisational system. To explore this hypothesis, we compared self-defining and everyday memories in adults with and without ASD. Results demonstrated that both groups were able to distinguish between self-defining and everyday memories, although the ASD group generated fewer specific memories overall. Despite qualitative similarities between the narratives of the two groups, the adults with ASD extracted less meaning from their narratives. Difficulties in eliciting meaning from memories suggests a failure in using past experiences to update the self. We therefore propose that the self-memory relationship might be static, rather than dynamic, in ASD.     

Temporal Cognition in Children with Autistic Spectrum Disorders: Tests of Diachronic Thinking

Impaired diachronic thinking-(the propensity and capacity to think about events spreading across time)-was demonstrated in a 2-Phase study in which children with autism were compared with age and ability matched controls. Identical tests of diachronic thinking were administered in both phases of the study, but to different participant groups, with the same results. The marked impairments shown are therefore robust. Various non-temporal explanations of the findings were eliminated by the results of control tasks in Phase 2. Diachronic thinking did not correlate with verbal or non-verbal ability, age, or mentalising ability, consistent with other evidence of the specificity of diachronic thinking ability. Possible causes of impaired diachronic thinking in autism are discussed.     

Autobiographical Memory and Social Problem-solving in Asperger Syndrome

Difficulties in social interaction are a central feature of Asperger syndrome. Effective social interaction involves the ability to solve interpersonal problems as and when they occur. Here we examined social problem-solving in a group of adults with Asperger syndrome and control group matched for age, gender and IQ. We also assessed autobiographical memory, on a cueing task and during social problem-solving, and examined the relationship between access to specific past experiences and social problem-solving ability. Results demonstrated a social problem-solving impairment in the Asperger group. Their solutions were less detailed, less effective and less extended in time. Autobiographical memory performance was also impaired with significantly longer latencies to retrieve specific memories and fewer specific memories retrieved in comparison to controls.     

Semantic amnesia without dementia: documentation of a case

We described the case of a patient affected by a progressive semantic memory disorder associated with prevalent temporal lobe atrophy. This deficit seems to be pure in the sense that it has not been found to overlap with other cognitive deficits (intellectual, linguistic, perceptual, visuo-spatial etc.) for a long time. Furthermore, despite his impaired semantic knowledge, the autobiographical memory of the patient was largely intact. This case therefore represents a form of semantic amnesia without dementia, and supports the hypothesis that there is a partial distinction between semantic and episodic memory.

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Sommario Descriviamo il caso di un paziente con atrofia bilaterale (prevalentemente temporale) affetto da un deficit progressivo semantico. Non si evidenziarono (almeno per lungo tempo) altri deficit cognitivi e la memoria autobiografica/episodica, in contrasto a quella semantica, risultò sufficientemente conservata. Il caso rappresenta, perciò, una forma di amnesia semantica in assenza di deterioramento cognitivo e sostiene l'ipotesi della distinzione tra memoria semantica ed episodica.

     

Sex Differences in Toddlers with Autism Spectrum Disorders

Although autism spectrum disorders (ASD) prevalence is higher in males than females, few studies address sex differences in developmental functioning or clinical manifestations. Participants in this study of sex differences in developmental profiles and clinical symptoms were 22 girls and 68 boys with ASD (mean age = 28 months). All children achieved strongest performance in visual reception and fine motor followed by gross motor and language functioning. Sex differences emerged in developmental profiles. Controlling for language, girls achieved higher visual reception scores than boys; boys attained higher language and motor scores and higher social-competence ratings than girls, particularly when controlling for visual reception. Longitudinal, representative studies are needed to elucidate the developmental and etiological significance of the observed sex differences.     

Episodic Memory and Remembering in Adults with Asperger Syndrome

A group of adults with Asperger syndrome and an IQ-matched control group were compared in remember versus know recognition memory. Word frequency was also manipulated. Both groups showed superior recognition for low-frequency compared with high-frequency words, and in both groups this word frequency effect occurred in remembering, not in knowing. Nor did overall recognition differ between the two groups. However, recognition in the Asperger group was associated with less remembering, and more knowing, than in the control group. Since remembering reflects autonoetic consciousness, which is the hallmark of an episodic memory system, these results show that episodic memory is moderately impaired in individuals with Asperger syndrome even when overall recognition performance is not.     

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.     

Episodic future thinking is impaired in the behavioural variant of frontotemporal dementia

Remembering the past and imagining the future are complex endeavours proposed to rely on a core neurobiological brain system. In the behavioural variant of frontotemporal dementia (bvFTD), regional patterns of brain atrophy affect medial prefrontal and temporal cortices of this core network. While autobiographical memory impairments have been documented in bvFTD, it remains unknown whether the ability to imagine future events is also compromised. Here, we investigated episodic future thinking in 10 bvFTD patients and contrasted their performance with Alzheimer's disease (AD, n = 10) and healthy matched Control (n = 10) participants. Participants were asked to remember 3 events from the previous year and to envisage 3 possible events that could occur in the next year. Both patient groups showed equivalent episodic detail performance for the retrieval of past events and the simulation of possible future episodes. Patients with bvFTD, however, showed additional impairments for the generation of external (non-episodic) details irrespective of condition. Voxel-based morphometry analyses revealed divergent neural correlates of episodic past and future thinking performance specific to each patient group. Atrophy in the posterior cingulate cortex was implicated in the disruption of past and future thinking in AD. In contrast, in bvFTD, disruption of past retrieval correlated with atrophy in medial prefrontal regions, whereas future thinking deficits were associated with atrophy of frontopolar, medial temporal regions including the right hippocampus, and lateral temporal and occipital cortices. Our results point to the involvement of multiple brain regions in facilitating retrieval of past, and simulation of future, events. Damage to any of these key regions thus adversely affects the ability to engage in personally relevant mental time travel.     

Personal semantic and episodic autobiographical memories in Korsakoff syndrome: A comparison of interview methods

Objective: The temporal gradient in patients with Korsakoff’s syndrome has been of particular interest in the literature, as many studies have found evidence for a steep temporal gradient, but others have observed more uniform remote memory impairment across all past time periods. Inconsistencies might be the result of the nature of remote memory impairment under study (i.e., nonpersonal or autobiographical memory) and of methodological differences in the examination of remote memory loss. The aim of this study was to examine whether differences between autobiographical memory interview (AMI) and autobiographical interview (AI) procedures influence the presence of a temporal gradient in semantic and episodic autobiographical memory in Korsakoff patients. Method: The procedure used in the present study combined the AMI and AI into one study session. We compared the performance of 20 patients with Korsakoff’s syndrome and 27 healthy controls. First, participants were asked to recall knowledge from different life periods. Second, participants were asked to recall memories from five life periods. Thirdly, participants were asked to rate their subjective experience of each event recalled on a 5-point scale. Finally, we analyzed the findings in terms of all the memories recalled versus the first memory from each life-period only. Results: Both the AMI and the AI showed a temporally graded retrograde amnesia in the Korsakoff patients for personal semantic and episodic autobiographical memories. The pattern of amnesia in Korsakoff patients was not affected by examining only one event per life-period. Subjective ratings of recalled memories were largely comparable between the groups. Conclusions: The findings were generally consistent across the AMI and AI. Varying the number of events did not affect the pattern of the gradient. Hence, the temporal gradient in Korsakoff patients is not an artefact of either the AMI or the AI method.     

Autobiographical memory and amnesia: Using conceptual knowledge to ground the self

A case of retrograde amnesia, PJM, elucidated the relationship between self, episodic memory and autobiographical knowledge. Results from a variety of measures including the I Am Memory Task (IAM Task), where memories are cued by self-generated self concepts, demonstrate that PJM has a coherent, continuous sense of self, despite having lost episodic memories for an 18-month period. Her use of conceptual autobiographical knowledge, in episodic tasks and to support aspects of identity, shows how autobiographical knowledge can support the self when episodic memories are inaccessible. These results are discussed with relation to current neuropsychological models of self and memory.     

Self-Reported Autism Symptoms in Adults with Autism Spectrum Disorders

Scores on the autism spectrum quotient (AQ) were examined in 65 adults with ASD. Maternal reports of symptoms were collected simultaneously using the autism diagnostic interview-revised (ADI-R) and the Vineland Screener. A slightly revised AQ administration procedure was used to accommodate adults with below average IQ. AQ scores were lower than in the original validation study, with only 11 adults (17%) scoring above the proposed diagnostic cut-off and 24 (27%) exceeding the screening cut-off. Adults with higher IQs endorsed more symptoms than those with below average intelligence, but even when analyses were restricted to the 39 adults with at least average IQ, only 44% met the screening cut-off. AQ scores were not significantly correlated with ADI-R or Vineland scores.     

Patterns of autobiographical memory impairment according to disease severity in semantic dementia

Studies of autobiographical memory in semantic dementia (SD) have yielded either a reversed temporal gradient or spared performances across the entire lifetime. This discrepancy might be owing to the fact that these studies did not take into account disease severity. Our aim was to study patterns of autobiographical memory impairment according to disease severity and to unravel their mechanisms in 14 SD patients, using an autobiographical memory task assessing overall and strictly episodic memories across the entire lifetime. We divided our patients in 2 subgroups of 7 patients each, one mild and one moderate according to their level of disease severity. The results indicated for the mild subgroup selective preserved performances for the most recent time period (last 12 months period) for both autobiographical memory scores. In the moderate subgroup, performances were impaired for both scores whatever the time period. Within-group comparisons across time periods showed a recency effect and a reminiscence bump in the mild subgroup and only a less important recency effect in the moderate subgroup, suggesting that with disease severity, old memories (reminiscence bump) tend to vanish and even recent memories are less well retrieved. A correlation analysis was carried out on the entire group, between the overall autobiographical memory score and performances provided by a general cognitive evaluation (semantic memory, executive functions, working and episodic memory). The results of this analysis reflect that mechanisms of disruption of autobiographical memory in SD predominantly involve a deficit of storage of semantic information in addition to faulty executive retrieval strategies. Finally, our result and those of the literature suggest the existence of 3 distinct autobiographical memory impairment patterns in SD according to disease severity: firstly preserved performances whatever the time period, secondly a reversed temporal gradient with a reminiscence bump and thirdly the appearance of a “step-function”.     

Autobiographical memory in semantic dementia: A longitudinal fMRI study

Whilst patients with semantic dementia (SD) are known to suffer from semantic memory and language impairments, there is less agreement about whether memory for personal everyday experiences, autobiographical memory, is compromised. In healthy individuals, functional MRI (fMRI) has helped to delineate a consistent and distributed brain network associated with autobiographical recollection. Here we examined how the progression of SD affected the brain's autobiographical memory network over time. We did this by testing autobiographical memory recall in a SD patient, AM, with fMRI on three occasions, each one year apart, during the course of his disease. At the outset, his autobiographical memory was intact. This was followed by a gradual loss in recollective quality that collapsed only late in the course of the disease. There was no evidence of a temporal gradient. Initially, AM's recollection was supported by the classic autobiographical memory network, including atrophied tissue in hippocampus and temporal neocortex. This was subsequently augmented by up-regulation of other parts of the memory system, namely ventromedial and ventrolateral prefrontal cortex, right lateral temporal cortex, and precuneus. A final step-change in the areas engaged and the quality of recollection then preceded the collapse of autobiographical memory. Our findings inform theoretical debates about the role of the hippocampus and neocortical areas in supporting remote autobiographical memories. Furthermore, our results suggest it may be possible to define specific stages in SD-related memory decline, and that fMRI could complement MRI and neuropsychological measures in providing more precise prognostic and rehabilitative information for clinicians and carers.     

Physical Activity Patterns in Youth with Autism Spectrum Disorders

The purpose of this study was to examine age-related physical activity patterns in youth with autism spectrum disorders (ASD). Thirty youth, aged 10–19 years, were divided into three groups: elementary (n=9), middle (n=9) and high (n=12) school. Participants wore an accelerometer and completed an activity questionnaire for seven consecutive days. The main findings were that (a) elementary youth are more active than the other groups, regardless type of day or time period, and (b) there are no consistent patterns in physical activity of youth with ASD according to day or time period. Findings emphasize that interventions for this population should address increasing extracurricular physical activity options during adolescence.     

Adults with Autism Spectrum Disorders using psychiatric hospitals in Ontario: Clinical profile and service needs

BackgroundAdults with Autism Spectrum Disorders (ASD) represent a small, but challenging sub-group of patients within Ontario's mental health care system. However, few studies have documented the clinical characteristics of this population and examined how such individuals differ from other psychiatric patients, with or without intellectual disabilities (ID).MethodA secondary analysis of data from the 2003 Comprehensive Assessment Projects from three psychiatric hospitals in Ontario was conducted to describe patients with ASD and ID and to determine how their profile compared to other hospital users.ResultsTwenty-three patients with ASD and ID were matched on gender and patient status (inpatient/outpatient) to individuals with and without ID. Individuals with ASD and ID were similar in terms of demographics to patients with and without ID. However, individuals with ASD and ID were younger, spent more days in hospital and were less likely to have a psychotic disorder diagnosis than both patients with and without ID. Inpatients with ASD and ID were recommended for a higher level of care than hospital service users without ID.ConclusionsClearly, this small sub-group of individuals within the hospital population has high clinical needs that are not always well met.