Brigitte Gilbert

Improvement of Episodic Memory in Persons with Mild Cognitive Impairment and Healthy Older Adults: Evidence from a Cognitive Intervention Program

The efficacy of cognitive training was assessed in persons with mild cognitive impairment (MCI) and persons with normal cognitive aging. Forty-seven participants were included in this study: 28 with MCI and 17 controls. Twenty-one participants received intervention (20 MCI and 9 controls) and 16 participants (8 MCI and 8 controls) received no intervention (waiting-list group). The intervention focused on teaching episodic memory strategies. Three tasks of episodic memory (list recall, face-name association, text memory) were used as primary outcome measures. Results were analyzed using analyses of variance. The intervention effect (pre- and post-intervention difference) was significant on two of the primary outcome measures (delayed list recall and face-name association). A significant pre-post-effect was also found on measures of subjective memory and well-being. There was no improvement in the performance of groups of individuals with MCI and normal elderly persons who did not receive the intervention. These results suggest that persons with MCI can improve their performance on episodic memory when provided with cognitive training.

Training-related brain plasticity in subjects at risk of developing Alzheimer’s disease

Subjects with mild cognitive impairment are at risk of developing Alzheimers disease. Cognitive stimulation is an emerging intervention in the field of neurology and allied sciences, having already been shown to improve cognition in subjects with mild cognitive impairment. Yet no studies have attempted to unravel the brain mechanisms that support such improvement. This study uses functional magnetic resonance imaging to measure the effect of memory training on brain activation in older adults with mild cognitive impairment and to assess whether it can reverse the brain changes associated with mild cognitive impairment. Brain activation associated with verbal encoding and retrieval was recorded twice prior to training and once after training. In subjects with mild cognitive impairment, increased activation was found after training within a large network that included the frontal, temporal and parietal areas. Healthy controls showed mostly areas of decreased activation following training. Comparison with pre-training indicated that subjects with mild cognitive impairment used a combination of specialized areas; that is, areas activated prior to training and new alternative areas activated following training. However, only activation of the right inferior parietal lobule, a new area of activation, correlated with performance. Furthermore, the differences between the brain activation patterns of subjects with mild cognitive impairment and those of healthy controls were attenuated by training in a number of brain regions. These results indicate that memory training can result in significant neural changes that are measurable with brain imaging. They also show that the brains of people with mild cognitive impairment remain highly plastic.

The Profile of Executive Functioning in Amnestic Mild Cognitive Impairment: Disproportionate Deficits in Inhibitory Control

Amnestic mild cognitive impairment (aMCI) represents a group of individuals who are highly likely to develop Alzheimers disease (AD). Although aMCI is typically conceptualized as involving predominantly deficits in episodic memory, recent studies have demonstrated that deficits in executive functioning may also be present, and thorough categorization of cognitive functioning in MCI may improve early diagnosis and treatment of AD. We first provide an extensive review of neuropsychology studies that examined executive functioning in MCI. We then present data on executive functioning across multiple sub-domains (divided attention, working memory, inhibitory control, verbal fluency, and planning) in 40 aMCI patients (single or multiple domain) and 32 normal elderly controls (NECs). MCI patients performed significantly worse than NECs in all 5 sub-domains, and there was impairment (>1.0 SD below the mean of NECs) in all sub-domains. Impairment on each test was frequent, with 100% of MCI patients exhibiting a deficit in at least one sub-domain of executive functioning. Inhibitory control was the most frequently and severely impaired. These results indicate that executive dysfunction in multiple sub-domains is common in aMCI and highlights the importance of a comprehensive neuropsychological evaluation for fully characterizing the nature and extent of cognitive deficits in MCI.

Executive Functions in Frontotemporal Dementia and Lewy Body Dementia

Diagnosis of different types of dementia is often based on clinical symptomatology rather than underlying pathology; therefore, accurate diagnosis depends on a thorough description of cognitive functioning in different dementias. Furthermore, direct comparison of cognitive functions between different types of dementia is necessary for differential diagnosis. Executive dysfunction is common in several types of dementia, including frontotemporal dementia (FTD) and Lewy body dementia (LBD); however, FTD and LBD patients have never been directly compared on measures of executive functioning. The authors compared the performance of 17 FTD and 15 LBD patients on 6 measures of executive functioning in terms of statistical group differences, mean severity of clinical impairment in comparison to normal controls, and frequency of impairment. Results indicated a remarkably similar pattern of performance across all areas examined in terms of mean performance, as well as degree and frequency of impairment. Only the Stroop test produced results that could potentially differentiate the patient groups. These findings suggest that both FTD and LBD should be considered disorders involving executive dysfunction.

How loss of meaning with preservation of phonological word form affects immediate serial recall performance: a linguistic account.

We present HP, a patient who following the occurrence of herpes simplex encephalitis, lost the ability to understand a subset of words while others remained preserved. Of particular interest is the fact that the meaningless items retained their lexical status. HP’s immediate serial recall of meaningless words was thus compared with that of meaningful words to assess the unique contribution of semantic knowledge without the confounding influence of phonological word (lexical) form. The results revealed a clear recall advantage for meaningful over meaningless words, indicating a specific contribution to recall from the semantic level of representation. Furthermore, an error analysis showed that phonemic errors were most common when semantic information was lacking. Interestingly, the same error pattern was found for pseudo-words that shared phonological elements with meaningless words. These findings support a linguistic and interactive activation account of short-term serial recall, which assumes that all levels of representation, including semantic knowledge about words, contribute to recall performance. In addition, the findings provide preliminary evidence that this view may be extended to the recall of pseudo-words, as there appear to be some influences of semantic representation on pseudo-word recall.

Predicting decline in mild cognitive impairment: A prospective cognitive study.

OBJECTIVE The primary aim of this study was to identify cognitive tests that differentiate between persons with mild cognitive impairment (MCI) who later develop cognitive decline and those who remain stable. METHOD This study used a prospective longitudinal design. One hundred twenty-two older adults with single-domain or multiple-domain amnestic MCI were recruited from memory clinics. They completed tests to measure baseline episodic memory, working memory, executive functions, perception, and language. They were then followed annually to determine with criteria independent from those tests whether they had remained stable or had developed dementia or significant cognitive decline. This was used as the reference standard to measure diagnostic test accuracy value. RESULTS ANOVAs indicated that participants with progressive MCI showed more impaired performance than those with stable MCI at baseline on episodic memory (word and story recall), the Brown-Peterson working memory test, object naming, object decision, and position of gap test. Logistic regression derived a significant model with 87.8% overall predictive value. The model included delayed text memory, free recall, naming, orientation match, object decision, and alpha span. Its sensitivity was 86.2% and its specificity was 88.9%. Positive predictive value was 83.3%, and negative predictive value was particularly high at 90.9%. CONCLUSIONS Identifying individuals with MCI who will progress to dementia or more severe cognitive impairment is a challenge. This study shows that cognitive measures provide valuable information regarding the predictive diagnosis of persons with MCI. Predictive accuracy of a cognitive battery might be optimized by selecting both memory and nonmemory measures.

Temporal preparation strategy may inflate RT deficit in patients with Parkinson's disease.

Twelve patients with Parkinson’s disease (PD) and 12 age-matched controls completed a visual reaction time (RT) task to assess the effect of temporal parameters on response preparation. Simple and choice RT conditions were presented in separate blocks. In both conditions, preparatory intervals of various durations (1, 3 and 5 s) were introduced between an auditory warning signal and the visual target. Within a block of trials, intervals varied randomly. The results indicated that PD patients responded slower than controls in both task conditions. Also, there was evidence for preparation in both groups, as RT decreased with increasing intervals. A three-way interaction indicated that PD patients’ RT was longer than that of controls at the shortest interval in simple RT. This suggests that PD patients show a different pattern of temporal response preparation and that this may contribute to their deficit on RT tasks.

Measuring the impact of cognitive and psychosocial interventions in persons with mild cognitive impairment with a randomized single-blind controlled trial: rationale and design of the MEMO+ study.

BACKGROUND Several studies have suggested that cognitive training is a potentially effective way to improve cognition and postpone cognitive decline in older adults with mild cognitive impairment (MCI). The MEMO+ study is a randomized, controlled, single-blind trial designed to test the efficacy, specificity, and long-term effect of a cognitive training intervention and a psychosocial intervention in persons with MCI. METHODS One hundred and sixty-two participants with MCI will be recruited. They will be randomized into three groups: cognitive training, psychosocial intervention, and no-contact. Each intervention will last for eight weeks (one session per week) and a booster training session will be provided three months after the end of the intervention. Various proximal and distal outcomes will be measured at pre-intervention as well as at one week, three months, and six months post-training. Proximal outcomes include memory and psychological health measures. Distal outcomes focus on self-rated functioning in complex daily activities and strategies used in daily life to enhance function. Socio-demographic factors (age, gender, and education), general cognition, personality traits, engagement in activities, and self-efficacy will be used as moderators. Enrolment began in April 2012 and will be completed by December 2014. CONCLUSIONS This study is likely to have a significant impact on the well-being of persons with MCI by contributing to the development of adapted and scientifically supported cognitive and psychosocial interventions.

MEMO+: Efficacy, Durability and Effect of Cognitive Training and Psychosocial Intervention in Individuals with Mild Cognitive Impairment

There is no consensus on the efficacy of cognitive training in persons with mild cognitive impairment (MCI) because of the paucity of well‐designed randomized controlled trials. The objective was to assess the effect of memory training on the cognitive functioning of persons with MCI and its durability and to evaluate whether this effect generalizes to daily life and whether positive effects could be obtained from psychosocial intervention.