The influence of cognitive impairment with no dementia on driving restriction and cessation in older adults.

Cognitively impaired older adults may be at increased risk of unsafe driving. Individuals with insight into their own impairments may minimize their risk by restricting or stopping driving. The purpose of this study was to examine the influence of cognitive impairment on driving status and driving habits and intentions. Participants were classified as cognitively impaired, no dementia single (CIND-single), CIND-multiple, or not cognitively impaired (NCI) and compared on their self-reported driving status, habits, and intentions to restrict or quit driving in the future. The groups differed significantly in driving status, but not in whether they restricted their driving or reduced their driving frequency. CIND-multiple group also had significantly higher intention to restrict/stop driving than the NCI group. Reasons for restricting and quitting driving were varied and many individuals reported multiple reasons, both external and internal, for their driving habits and intentions. Regardless of cognitive status, none of the current drivers were seriously thinking of restricting or quitting driving in the next 6 months. It will be important to determine, in future research, how driving practices change over time and what factors influence decisions to restrict or stop driving for people with cognitive impairment.

Including persistency of impairment in mild cognitive impairment classification enhances prediction of 5-year decline.

Although older adults with Mild Cognitive Impairment (MCI) show elevated rates of conversion to dementia as a group, heterogeneity of outcomes is common at the individual level. Using data from a prospective 5-year longitudinal investigation of cognitive change in healthy older adults (N = 262, aged 64-92 years), this study addressed limitations in contemporary MCI identification procedures which rely on single occasion assessment ("Single-Assessment [SA] MCI") by evaluating an alternate operational definition of MCI requiring evidence of persistent cognitive impairment over multiple-testing sessions ("Multiple-Assessment [MA] MCI"). As hypothesized, prevalence of SA-MCI exceeded that of MA-MCI. Further, the MA-MCI groups showed lower baseline cognitive and functional performance and steeper cognitive decline compared with Control and SA-MCI group. Results are discussed with reference to retest effects and clinical implications.

Intraindividual variability in reaction time predicts cognitive outcomes 5 years later.

OBJECTIVE: Building on results suggesting that intraindividual variability in reaction time (inconsistency) is highly sensitive to even subtle changes in cognitive ability, this study addressed the capacity of inconsistency to predict change in cognitive status (i.e., cognitive impairment, no dementia [CIND] classification) and attrition 5 years later. METHOD: Two hundred twelve community-dwelling older adults, initially aged 64-92 years, remained in the study after 5 years. Inconsistency was calculated from baseline reaction time performance. Participants were assigned to groups on the basis of their fluctuations in CIND classification over time. Logistic and Cox regressions were used. RESULTS: Baseline inconsistency significantly distinguished among those who remained or transitioned into CIND over the 5 years and those who were consistently intact (e.g., stable intact vs. stable CIND, Wald (1) = 7.91, p < .01, Exp(ß) = 1.49). Average level of inconsistency over time was also predictive of study attrition, for example, Wald (1) = 11.31, p < .01, Exp(ß) = 1.24. CONCLUSIONS: For both outcomes, greater inconsistency was associated with a greater likelihood of being in a maladaptive group 5 years later. Variability based on moderately cognitively challenging tasks appeared to be particularly sensitive to longitudinal changes in cognitive ability. Mean rate of responding was a comparable predictor of change in most instances, but individuals were at greater relative risk of being in a maladaptive outcome group if they were more inconsistent rather than if they were slower in responding. Implications for the potential utility of intraindividual variability in reaction time as an early marker of cognitive decline are discussed.

Intraindividual variability is related to cognitive change in older adults: evidence for within-person coupling.

In this study, the authors addressed the longitudinal nature of intraindividual variability over 3 years. A sample of 304 community-dwelling older adults, initially between the ages of 64 and 92 years, completed 4 waves of annual testing on a battery of accuracy- and latency-based tests covering a wide range of cognitive complexity. Increases in response-time inconsistency on moderately and highly complex tasks were associated with increasing age, but there were significant individual differences in change across the entire sample. The time-varying covariation between cognition and inconsistency was significant across the 1-year intervals and remained stable across both time and age. On occasions when intraindividual variability was high, participants' cognitive performance was correspondingly low. The strength of the coupling relationship was greater for more fluid cognitive domains such as memory, reasoning, and processing speed than for more crystallized domains such as verbal ability. Variability based on moderately and highly complex tasks provided the strongest prediction. These results suggest that intraindividual variability is highly sensitive to even subtle changes in cognitive ability.

Self-reported cognitive inconsistency in older adults.

Insight into one's own cognitive abilities, or metacognition, has been widely studied in developmental psychology. Relevance to the clinician is high, as memory complaints in older adults show an association with impending dementia, even after controlling for likely confounds. Another candidate marker of impending dementia under study is inconsistency in cognitive performance over short time intervals. Although there has been a recent proliferation of studies of cognitive inconsistency in older adults, to date, no one has examined adults' self-perceptions of cognitive inconsistency. Ninety-four community-dwelling older adults (aged 70-91) were randomly selected from a parent longitudinal study of short-term inconsistency and long-term cognitive change in aging. Participants completed a novel 40-item self-report measure of everyday cognitive inconsistency, including parallel scales indexing perceived inconsistency 5 years ago and at present, yielding measures of past, present, and 5-year change in inconsistency. The questionnaire showed acceptable psychometric characteristics. The sample reported an increase in perceived inconsistency over time. Higher reported present inconsistency and greater 5-year increase in inconsistency were associated with noncognitive (e.g., older age, poorer ADLs, poorer health, higher depression), metacognitive (e.g., poorer self-rated memory) and neuropsychological (e.g., poorer performance and greater 5-year decline in global cognitive status, vocabulary, and memory) measures. Correlations between self-reported inconsistency and neuropsychological performance were attenuated, but largely persisted when self-rated memory and age were controlled. Observed relationships between self-reported inconsistency and measures of neuropsychological (including memory) status and decline suggest that self-perceived inconsistency may be an area of relevance in evaluating older adults for memory disorders.

Characterizing executive functioning in older special populations: from cognitively elite to cognitively impaired.

The authors examined the structure and invariance of executive functions (EF) across (a) a continuum of cognitive status in 3 groups of older adults (cognitively elite [CE], cognitively normal [CN], and cognitively impaired [CI]) and (b) a 3-year longitudinal interval. Using latent variable analyses (LISREL 8.80), the authors tested 3-factor models ("Inhibition": Hayling [Burgess & Shallice, 1997], Stroop [Regard, 1981]; "Shifting": Brixton [Burgess & Shallice, 1997], Color Trails [D'Elia et al., 1996]; and "Updating": Reading and Computational Span [Salthouse & Babcock, 1991]) and 1-factor models within each group. Participants (initial N = 570; 53-90 years) were from the Victoria Longitudinal Study (Sample 3, Waves 1 and 2). Cross-sectionally, the authors observed a 3-factor EF structure especially for the CE group and 1-factor solutions for all 3 groups. Longitudinally, temporal invariance was supported for the 3-factor model (CE and CN groups) and the 1-factor model (CI and CN groups). Subgroups with higher cognitive status and greater 3-year stability performed better on EF factors than corresponding groups with lower cognitive status and less stability. Studies of EF structure, performance, dedifferentiation, and dysfunction will benefit from considering initial cognitive status and longitudinal stability.

The relationship between everyday problem solving and inconsistency in reaction time in older adults.

The purpose of the present study was to investigate whether inconsistency in reaction time (RT) is predictive of older adults' ability to solve everyday problems. A sample of 304 community dwelling non-demented older adults, ranging in age from 62 to 92, completed a measure of everyday problem solving, the Everyday Problems Test (EPT). Inconsistency in latencies across trials was assessed on four RT tasks. Performance on the EPT was found to vary according to age and cognitive status. Both mean latencies and inconsistency were significantly associated with EPT performance, such that slower and more inconsistent RTs were associated with poorer everyday problem solving abilities. Even after accounting for age, education, and mean level of performance, inconsistency in reaction time continued to account for a significant proportion of the variance in EPT scores. These findings suggest that indicators of inconsistency in RT may be of functional relevance.

Functional abilities in older adults with mild cognitive impairment.

BACKGROUND: A classification scheme and general set of criteria for diagnosing mild cognitive impairment (MCI) were recently proposed by a multidisciplinary group of experts who met at an international symposium on MCI. One of the proposed criteria included preserved basic activities of daily living and minimal impairment in complex instrumental activities of daily living (IADLs). OBJECTIVE: To investigate whether older adults with MCI classified according to the subtypes identified by the Working Group (i.e. amnestic, single non-memory domain, and multiple domain with or without a memory component) differed from cognitively intact older adults on a variety of measures indexing IADLs and to examine how well measures of IADL predict concurrent MCI status. METHODS: Two hundred and fifty community-dwelling older adults, ranging in age from 66 to 92, completed self-report measures of IADLs (Lawton and Brody IADL Scale, Scales of Independent Behaviour-Revised--SIB-R) and a measure of everyday problem solving indexing IADLs (Everyday Problems Test--EPT). Ratings of participants' IADL functioning were also obtained from informants (e.g. spouse, adult child and friend). RESULTS: Older adults with multiple-domain MCI demonstrated poorer IADL functioning than older adults with no cognitive impairment on the EPT and the SIB-R (both self- and informant-report versions). The multiple-domain MCI participants also demonstrated poorer IADLs than MCI participants with impairments in a single cognitive domain on the self-reported SIB-R and EPT. The single-domain MCI groups demonstrated poorer IADLs than older adults without cognitive impairment on the informant-reported SIB-R and EPT. No significant group differences were found on the Lawton and Brody IADL Scale. Using the EPT and SIB-R as predictors in a multinomial regression analysis, MCI group status was reliably predicted, but the classification rate was poor. CONCLUSION: Individuals with MCI demonstrated poorer IADL functioning compared to cognitively intact older adults. However, the changes in IADL functioning observed in MCI may be too subtle to be detected by certain measures, such as the Lawton and Brody IADL Scale.

Cognitive abilities and functional capacity in older adults: results from the modified Scales of Independent Behavior-Revised.

The relationship between cognitive and functional abilities was examined in a sample of community-dwelling older adults. Self and informant (e.g., spouse) reports of participants' functional status were obtained on the modified Scales of Independent Behavior-Revised (mSIB-R). Participants also completed measures of processing speed, episodic memory, executive functioning, and verbal ability. Results showed that the mSIB-R correlated positively with cognitive variables. Hierarchical regression analyses suggested that each mSIB-R factor is predicted by somewhat different cognitive variables, after adjusting for demographic, health, and motor variables. This report-based measure was as accurate as a performance-based measure in classifying cognitive groups. Informant social/cognitive engagement and self physical/environment engagement factors showed the most promise in this regard. The findings reveal links between cognitive and functional abilities in a sample with varying degrees of cognitive impairment.

Intraindividual variability across cognitive domains: investigation of dispersion levels and performance profiles in older adults.

A growing body of research suggests that substantial variability exists among cognitive abilities within individuals. This within-person variability across cognitive domains is termed dispersion. The present study investigated the relationship between aging and dispersion of cognitive functions both quantitatively (overall levels of dispersion) and qualitatively (patterns of dispersion) in a sample of 304 nondemented, older adults aged 64 to 92 years (M = 74.02). Quantitatively, higher levels of dispersion were observed in the old-old adults (aged 75-92 years) and those identified as having experienced cognitive decline, suggesting that dispersion level may serve as a marker of cognitive integrity. Qualitatively, three distinct dispersion profiles were identified through clustering methods, and these were found to be related to demographic, health, and performance characteristics of the individuals, suggesting that patterns of dispersion may be meaningful indicators of individual differences.

Differential neuropsychological test sensitivity to left temporal lobe epilepsy.

We examined the sensitivity of the Rey Auditory Verbal Learning Test (AVLT), California Verbal Learning Test (CVLT), Boston Naming Test (BNT), and Multilingual Aphasia Examination Visual Naming subtest (MAE VN) to lateralized temporal lobe epilepsy (TLE) in patients who subsequently underwent anterior temporal lobectomy. For the AVLT (n = 189), left TLE patients performed more poorly than their right TLE counterparts [left TLE = 42.9 (10.6), right TLE = 47.7 (9.9); p < .002 (Cohen's d = .47)]. Although statistically significant, the CVLT group difference (n = 212) was of a smaller magnitude [left LTE = 40.7 (11.1), right TLE = 43.8 (9.9); (p < .03, Cohen's d = .29)] than the AVLT. Group differences were also present for both measures of confrontation naming ability [BNT: left LTE = 43.1 (8.9), right TLE = 48.1 (8.9); p < .001 (Cohen's d = .56); MAE VN: left TLE = 42.2, right TLE = 45.6, p = .02 (Cohen's d = .36)]. When these data were modeled in independent logistic regression analyses, the AVLT and BNT both significantly predicted side of seizure focus, although the positive likelihood ratios were modest. In the subset of 108 patients receiving both BNT and AVLT, the AVLT was the only significant predictor of seizure laterality, suggesting individual patient variability regarding whether naming or memory testing may be more sensitive to lateralized TLE.

Within-person variability in response speed as an indicator of cognitive impairment in older adults.

Within-person variability may be an important indicator of central nervous system compromise. In this study, within-person variability in response speed was examined in community-dwelling older adults, ages 64-92 years, using a new framework that takes into account both the extent (single versus multiple domains affected) and nature (amnestic versus non-amnestic) of the cognitive impairment. Those with multiple domains of impairment were more variable than those who showed an isolated area of impairment, regardless of whether memory was one of the domains affected. Further, for those with difficulties in two or more non-memory domains, increased variability was most evident in more cognitively demanding situations, when individuals had to manipulate information held briefly in mind, switch cognitive set or inhibit an automatic response. Finally, group differentiation was better achieved when within-person variability as opposed to mean speed of performance was considered.

Short-term changes in general and memory-specific control beliefs and their relationship to cognition in younger and older adults.

We examined short-term changes in younger and older adults' control beliefs. Participants completed measures of general and memory-specific competence and locus of control on 10 bi-monthly occasions. At each occasion, participants rated their control beliefs prior to and following completion of a battery of cognitive tasks. Exposure to the set of cognitively demanding tasks led to declines in older adults' ratings of both general and memory-specific competence compared to little change or increases in younger adults' ratings. Older adults were also more inconsistent in their reported locus of control beliefs across the 10 occasions. Analyses examining the relationship between control beliefs and actual cognitive performance revealed few significant effects, suggesting that short-term changes in perceived control are not driven by monitoring changes in actual performance. The results suggest the importance of assessing short-term as well as long-term changes in perceived control to obtain a complete picture of aging-related changes.

Reaction time inconsistency in a spatial stroop task: age-related differences through childhood and adulthood.

Age-related differences in inconsistency of reaction time (RT) across the life span were examined on a task with differing levels of demand on executive control. A total of 546 participants, aged 5 to 76 years, completed a spatial Stroop task that permitted observations under three conditions (congruent, incongruent, and neutral) according to the correspondence between the required response (based on stimulus direction) and stimulus location. An interference effect was observed across all ages. Analyses of neutral condition data replicated previous research demonstrating RT inconsistency follows a U-shaped developmental curve across the life span. The relationship between age and inconsistency, however, depended on condition: inconsistency in the congruent condition was higher than inconsistency in both the neutral and incongruent conditions across middle-aged groups. Reaction time inconsistency may reflect processing efficiency that is maximal in young adulthood and may also be sensitive to fluctuations in performance that reflect momentarily highly efficient responding.

Was that part of the story or did i just think so? Age and cognitive status differences in inference and story recognition.

This study expanded the inference and story recognition literature by investigating differences within the older age range, differences as a result of cognitive impairment, no dementia (CIND), and applying signal detection procedures to the analysis of accuracy data. Old-old adults and those with more severe CIND showed poorer ability to accurately recognize inferences, and less sensitivity in discriminating between statement types. Results support the proposal that participants used two different recognition strategies. Old-old and CIND adults may be less able to recognize that something plausible with an event may not have actually occurred.

Neurocognitive markers of cognitive impairment: exploring the roles of speed and inconsistency.

A well-known challenge for research in the cognitive neuropsychology of aging is to distinguish between the deficits and changes associated with normal aging and those indicative of early cognitive impairment. In a series of 2 studies, the authors explored whether 2 neurocognitive markers, speed (mean level) and inconsistency (intraindividual variability), distinguished between age groups (64-73 and 74-90+ years) and cognitive status groups (nonimpaired, mildly impaired, and moderately impaired). Study 1 (n = 416) showed that both level and inconsistency distinguished between the age and 2 cognitive status (not impaired, mildly impaired) groups, with a modest tendency for inconsistency to predict group membership over and above mean level. Study 2 (n = 304) replicated these results but extended them because of the qualifying effects associated with the unique moderately impaired oldest group. Specifically, not only were the groups more firmly distinguished by both indicators of speed, but evidence for the differential contribution of performance inconsistency was stronger. Neurocognitive markers of speed and inconsistency may be leading indicators of emerging cognitive impairment.

Reaction time performance in adolescents with attention deficit/hyperactivity disorder: evidence of inconsistency in the fast and slow portions of the RT distribution.

Inconsistency across trials of 2-choice reaction time (RT) data was analyzed in 72 adolescents (age 12-17 years) within 4 groups differentiated by the presence or absence of attention deficit/hyperactivity disorder (ADHD) and reading difficulties (RD). ADHD participants were more inconsistent (across all trials, and in the slow portion of the RT distribution) than controls, but only when RD was present. Within the fast portion of the RT distribution, ADHD participants were more inconsistent than controls regardless of RD. The results highlight the importance of fluctuations in cognitive performance in ADHD and suggest that there may be independent sources of variation in inconsistency affecting the fast and slow portions of the RT distribution.

Cognitive functioning and everyday problem solving in older adults.

The relationship between cognitive functioning and a performance-based measure of everyday problem-solving, the Everyday Problems Test (EPT), thought to index instrumental activities of daily living (IADL), was examined in 291 community-dwelling non-demented older adults. Performance on the EPT was found to vary according to age, cognitive status, and education. Hierarchical regression analyses revealed that, after adjusting for demographic and health variables, measures of cognitive functioning accounted for 23.6% of the variance in EPT performance. In particular, measures of global cognitive status, cognitive decline, speed of processing, executive functioning, episodic memory, and verbal ability were significant predictors of EPT performance. These findings suggest that cognitive functioning along with demographic variables are important determinants of everyday problem-solving.

Aging and response inhibition: Normative data for the Victoria Stroop Test.

Increased difficulty with response inhibition occurs with age, although there is some controversy as to whether increased interference on Stroop tasks reflects difficulties with response inhibition or simply reflects generalized cognitive slowing. The Victoria Stroop Test (VST) is a brief, easily administered, psychometrically sound version of Stroop's original task. Performance on the VST by adults across a wide age span was examined to determine the association between age and various measures of interference. In addition, normative data for the VST were calculated. Participants were 272 healthy, community-dwelling adults age 18 to 94. Age and speed were negatively correlated on all trials of the VST. Importantly, however, interference scores that were corrected for baseline slowing remained highly correlated with age. Similarly, age and error scores on the interference trial were positively correlated, indicating decreased accuracy with age. These findings suggest that increased interference on Stroop tasks with age is not accounted for by simple cognitive slowing and more likely reflects other cognitive changes, such as decreased response inhibition. The VST has a number of administrative and psychometric strengths, and the provision of normative data should enhance its potential for clinical and research applications.

Structure of four executive functioning tests in healthy older adults.

The authors examined the factor structure of 4 indicators of executive functioning derived from 2 new (i.e., Hayling and Brixton) and 2 traditional (i.e., Stroop and Color Trails) tests. Data were from a cross-sectional sample of 55- to 85-year-old healthy adults (N=427) from the Victoria Longitudinal Study. Confirmatory factor analysis (LISREL 8.52) tested both a 2-factor model of Inhibition (Hayling, Stroop) and Shifting (Brixton, Color Trails) and a single-factor model. The 2-factor model did not fit the data because the covariance matrix of the factors was not positive definite. The single-factor model fit the data well, chi(2)(2, N=427)=0.32, p=.85, root-mean-square error of approximation (RMSEA)=.00, comparative fit index (CFI)=1.00, goodness-of-fit index (GFI)=1.00. Moreover, the single-factor structure of executive functioning was invariant (configural and metric) across gender, and invariant (configural with limited metric) across age. Structural relations showed that poorer executive functioning performance was related to older age and lower fluid intelligence, chi(2)(11, N=418)=23.04, p=.02, RMSEA=.05, CFI=.97, GFI=.98.