Characterizing Magnitude and Selectivity of Attrition in a Study of Mild Cognitive Impairment

OBJECTIVES

Attrition is one of the greatest difficulties in longitudinal studies on cognitive ageing because of the associated risk of underestimating declines. The aims of this paper were to characterize the magnitude and selectivity of attrition in a study of mild cognitive impairment.

DESIGN

Forty two patients with multiple-domain amnestic MCI, 71 with single-domain amnestic MCI, 35 with non-amnestic MCI and 318 healthy controls were recruited from primary care centers and assessed at baseline.

MEASUREMENTS

All participants underwent extensive neuropsychological evaluation, including the Mini-Mental State Examination, the Californian Verbal Learning Test, the CAMCOG-R battery, the Counting Span task and Listening Span task, and the Subjective Memory Complaints Questionnaire.

RESULTS

21.5% of the participants at baseline did not participate in the follow-up assessment. Comparison between respondents and non-returners did not reveal differences in cognitive performance in the MCI group. Data obtained at the initial assessment regarding comorbidity, social activities and attention given to memory training enabled prediction of the status of the participants in the follow-up assessment.

CONCLUSION

Identification of potential non- returners is relevant, especially in MCI studies, in order to develop retention strategies to minimize attrition.

Visual memory profiling with CANTAB in mild cognitive impairment (MCI) subtypes

OBJECTIVE

Although visual memory has been shown to be impaired in amnestic mild cognitive impairment (aMCI), the differences between MCI subtypes are not well defined. The current study attempted to investigate visual memory profiles in different MCI subtypes.

METHODS

One hundred and seventy volunteers aged older than 50 years performed several visual memory tests included in the CANTAB battery. Participants were classified into four groups: (1) multiple domain aMCI (mda-MCI) (32 subjects); (2) single domain aMCI (sda-MCI)(57 subjects); (3) multiple domain non amnestic MCI (mdna-MCI) (32 subjects); and (4) controls (54 healthy individuals without cognitive impairment). Parametric and non parametric analyses were performed to compare the groups and to obtain their corresponding memory profiles.

RESULTS

The mda-MCI group exhibited impairments in both dimensions of episodic memory (recognition and recollection/recall), and also in learning and working memory, whereas the sda-MCI only showed impairment in recollection-delayed recall and learning. The mdna-MCI group displayed impairment in working memory but good preservation of learning and episodic memory.

CONCLUSION

The CANTAB visual memory profiles may contribute to better cognitive characterization of patients with different MCI subtypes, allowing comparison across several processes involved in visual memory such as attention, recognition, recollection and working memory.

Do the Cambridge Neuropsychological Test Automated Battery episodic memory measures discriminate amnestic mild cognitive impairment?

OBJECTIVE

Although visual recognition memory and visuospatial paired associates learning has been shown to be impaired in amnestic mild cognitive impairment (aMCI), the sensitivity and specificity of the visual memory tests used to identify aMCI are not well defined. The current study attempted to analyze the sensitivity and specificity of three visual episodic memory tests (Pattern Recognition Memory [PRM], Delayed Matching to Sample [DMS], and Paired Associated Learning [PAL]) from the CANTAB, in differentiating aMCI patients from control healthy participants.

METHODS

Seventy seven aMCI patients and 85 cognitive normal controls aged over 50 years performed the PRM, DMS, and PAL tests. Univariate and multivariate logistic regression and receiver operating characteristic curve analyses were used to study the relationships between aMCI and visual memory measures.

RESULTS

The three Cambridge Neuropsychological Test Automated Battery measures significantly predicted aMCI. The optimal predictive model combined the total percent correct responses for PRM and DMS with the PAL total errors (six shapes adjusted), with a sensitivity of 72%, specificity of 83%, and achieved predictive accuracy of 80%.

CONCLUSION

Visual episodic memory tasks such as those involved in the PRM, DMS, and PAL tests (included in the Cambridge Neuropsychological Test Automated Battery) may sensitively discriminate aMCI patients from normal controls. These tests may be useful for correct diagnosis of aMCI.

Prevalence and correlates of mild cognitive impairment in adults aged over 50 years with subjective cognitive complaints in primary care centers

AIM

To examine the prevalence and correlates of mild cognitive impairment in adults aged over 50 years attending primary care centers with complaints of cognitive failure.

METHODS

A sample of 689 individuals aged ≥ 50 years with no previous diagnosis of dementia was assessed by use of the Mini-Mental State Examination, the Cambridge Cognitive Examination-Revised and the California Verbal Learning Test--to evaluate the mild cognitive impairment as dependent variables--and administration of a questionnaire on cognitive complaints and other instruments--to measure correlates.

RESULTS

The prevalence of mild cognitive impairment was 31.40%, and positive associations were found for age, occupation, subjective memory complaints, reading habits and level of vocabulary. In the logistic regression, modeled mild cognitive impairment was associated with age (70 years or older), subjective cognitive complaints and level of vocabulary.

CONCLUSION

Almost one-third of the adults aged ≥ 50 years attending primary care centers with subjective cognitive complaints were affected by mild cognitive impairment. Early evaluation of cognitive functioning is essential to establish adequate preventive and intervention strategies.

Prevalence and correlates of cognitive impairment in adults with subjective memory complaints in primary care centres

AIMS

To examine the prevalence and correlates of cognitive impairment (CI) in adults over 50 years old attending primary care centres with complaints of memory failure.

METHODS

A sample of 580 individuals aged 50+ years with no previous diagnosis of dementia was assessed by use of the Mini Mental State Examination, the Cambridge Cognitive Assessment-Revised and the California Verbal Learning Test - to evaluate CI-dependent variables - and administration of a questionnaire on memory complaints and other instruments - to measure correlates.

RESULTS

The prevalence of CI was 46.20% and positive associations were found for age, gender, level of education, subjective memory complaints, instrumental activities of daily living, reading habits and frequency of leisure activities. In the logistic regression, modelled CI was associated with older age, gender (49.12% women, 39.66% men), instrumental activities of daily living, and reading habits.

CONCLUSION

Almost half of the adults aged 50+ years attending primary care centres with subjective memory complaints were affected by CI. Early evaluation of cognitive functioning is essential to establish adequate preventive and intervention strategies.

Tip-of-the-tongue in aging: influence of vocabulary, working memory and processing speed

BACKGROUND AND AIMS

It is well known that tip-of-the-tongue (ToT) states, which are due to failure in the phonological activation of words, especially proper names, are more common in older than in younger adults. Nevertheless, the relationship between increased numbers of ToTs and cognitive aging remains unclear. The aim of the present study was to clarify this relationship by examining ToT production and the performance of cognitive tasks such as working memory and processing speed tests.

METHODOLOGY

In order to study the relationships between these constructs, the performance of 133 participants in different language, working memory and processing speed tasks was analysed by use of LISREL software.

RESULTS

The best fit model included direct and indirect effects of age, mediated by cognitive variables, on lexical production variables. The model incorporated the indirect effects of age on vocabulary through working memory and also the indirect effect of age on ToT through processing speed.

CONCLUSION

The results indicate negative modulation of slowed processing in the age-related increase of ToT and positive modulation of working memory in vocabulary, as well as an absence of any relation between vocabulary and ToT. Assuming that ToT events involve controlled processes, the relationship between slowed processing and ToT in aging could be interpreted as reflecting controlled compensatory mechanisms.

Cognitive interference and aging: insights from a spatial stimulus-response consistency task

One hundred and thirty-one adults belonging to four age groups (19-26, 50-59, 60-69 and 70-82 years) performed a spatial stimulus-response consistency task in which the response dimension (left or right) overlapped relevant and irrelevant stimulus dimensions. The influence of the irrelevant stimulus dimension on response time was significantly greater in the middle age groups than among 19-26 year-olds, and significantly greater in the highest age group than in any other. This pattern persisted when allowance was made for a significant age-related increase in processing time (measured as reaction time in a single-stimulus, single-response task). It is concluded that in tasks of the kind used, the elderly resist interference from the irrelevant information less easily than do younger persons. Interestingly, comparison of Vincentized quintiles suggested that the effect of the irrelevant stimulus dimension decreased with increasing response time among 19-26 year-olds, but increased with response time among 70-82 year-olds.

Narrative speech in aging: quantity, information content, and cohesion

This study examined age-related changes in narrative speech of 79 adults aged 40-91 who told stories from their pictorial representations. Quantity, information content and cohesion of narratives were analysed using a detailed transcription and codification system. We carried out a LISREL analysis to study relationships between narrative performance and age, level of education and verbal capacity. Our results showed that aging increases quantity, reduces density of informational content and cohesive reference of narratives and increases the units of irrelevant content. Verbal capacity measured by a vocabulary test improves content and cohesion. The implications of the findings for the cognitive deficit and pragmatic change explanations of narrative speech are discussed.