Longitudinal change in language production: effects of aging and dementia on grammatical complexity and propositional content

The effect of cognitive function healthcare using AI robot for older adults: A systematic review and meta-analysis

Background

With rapidly aging populations in most parts of the world, it is only natural that the need for caregivers for older adults is going to increase in the near future. Therefore, most technologically proficient countries are in the process of using artificial intelligence (AI) to build socially assistive robots (SAR) to play the role of caregivers in enhancing interaction and social participation among older adults.

Objective

This study aimed to examine the effect of intervention through AI SAR on the cognitive function of older adults through a systematic literature review.

Methods

We conducted a meta-analysis of the various existing studies on the effect of AI SAR on the cognitive function of older adults to standardize the results and clarify the effect of each method and indicator. Cochrane collaboration and the systematic literature review flow of PRISMA (Preferred Reporting Item Systematic Reviews and Meta-Analyses) were used on original, peer-reviewed studies published from January 2010 to March 2022. The search words were derived by combining keywords including Population, Intervention, and Outcome—according to the Population, Intervention, Comparison, Outcome, Time, Setting, and Study Design principle—for the question “What is the effect of AI SAR on the cognitive function of older adults in comparison with a control group?” (Population: adults aged ≥65 years; Intervention: AI SAR; Comparison: comparison group; Outcome: popular function; and Study Design: prospective study). For any study, if one condition among subjects, intervention, comparison, or study design was different from those indicated, the study was excluded from the literature review.

Results

In total, 9 studies were selected (6 randomized controlled trials and 3 quasi-experimental design studies) for the meta-analysis. Publication bias was examined using the contour-enhanced funnel plot method to confirm the reliability and validity of the 9 studies. The meta-analysis revealed that the average effect size of AI SAR was shown to be Hedges g=0.43 (95% CI –0.04 to 0.90), indicating that AI SAR are effective in reducing the Mini Mental State Examination scale, which reflects cognitive function.

Conclusions

The 9 studies that were analyzed used SAR in the form of animals, robots, and humans. Among them, AI SAR in anthropomorphic form were able to improve cognitive function more effectively. The development and expansion of AI SAR programs to various functions including health notification, play therapy, counseling service, conversation, and dementia prevention programs are expected to improve the quality of care for older adults and prevent the overload of caregivers. AI SAR can be considered a representative, digital, and social prescription program and a nonpharmacological intervention program that communicates with older adults 24 hours a day. Despite its effectiveness, ethical issues, the digital literacy needs of older adults, social awareness and reliability, and technological advancement pose challenges in implementing AI SAR. Future research should include bigger sample sizes, pre-post studies, as well as studies using an older adult control group.

Psycholinguistic Screening for Cognitive Decline in Cancer Survivors: A Feasibility Study

OBJECTIVES

To test the feasibility of using psycholinguistic speech analysis as a proxy for cognitive function in men undergoing treatment for prostate cancer.

SAMPLE & SETTING

Audio-recorded speech samples were collected from 13 men enrolled in a parent study at the University of Kansas Cancer Center in Kansas City.

METHODS & VARIABLES

Audio-recorded speech samples, collected from clinical interviews and in response to a prompt question during the parent study at two time points, were evaluated to determine feasibility relationships between neurocognitive and psycholinguistic measures.

RESULTS

Correlations between neurocognitive and psycholinguistic measures were identified for prompted speech, but the strength of relationships varied between time points. No relationships were identified in clinical interview speech samples.

IMPLICATIONS FOR NURSING

Feasibility was demonstrated for recording, transcribing, and analyzing speech from clinical interviews, and results suggest relationships between neurocognitive and psycholinguistic measures in prompted speech. If validated, psycholinguistic assessments may be used to assess cognitive function in cancer survivors. Advances in natural language processing may provide opportunities for automated speech analyses for cancer treatment-related cognitive decline.

Cognitive Intervention Through Photo-Integrated Conversation Moderated by Robots (PICMOR) Program: A Randomized Controlled Trial

Social interaction might prevent or delay dementia, but little is known about the specific effects of various social activity interventions on cognition. This study conducted a single-site randomized controlled trial (RCT) of Photo-Integrated Conversation Moderated by Robots (PICMOR), a group conversation intervention program for resilience against cognitive decline and dementia. In the RCT, PICMOR was compared to an unstructured group conversation condition. Sixty-five community-living older adults participated in this study. The intervention was provided once a week for 12 weeks. Primary outcome measures were the cognitive functions; process outcome measures included the linguistic characteristics of speech to estimate interaction quality. Baseline and post-intervention data were collected. PICMOR contains two key features: 1) photos taken by the participants are displayed and discussed sequentially; and 2) a robotic moderator manages turn-taking to make sure that participants are allocated the same amount of time. Among the primary outcome measures, one of the subcategories of cognitive functions, verbal fluency significantly improved in the intervention group. Among the process outcome measures, a part of the subcategories of linguistic characteristics of speech, the amount of speech and richness of words, proportion of providing topics, questions, and answers in total utterances were larger for the intervention group. This study demonstrated for the first time the positive effects of a robotic social activity intervention on cognitive function in healthy older adults via RCT. The group conversation generated by PICMOR may improve participants’ verbal fluency since participants have more opportunity to provide their own topics, asking and answering questions which results in exploring larger vocabularies. PICMOR is available and accessible to community-living older adults.

Clinical Trial Registration:UMIN Clinical Trials Registry, identifier UMIN000036667.

Effects of incidental physical activity on morphosyntactic processing in aging

Older adults have difficulties in sentence comprehension when working memory (WM) load increases (e.g., multiple embedded clauses). Structured physical activity has been related to improvements in cognition; however, incidental physical activity (PA, i.e., unstructured daily physical activities), particularly incidental vigorous activity has been poorly studied in relation to its effects on behavior. Furthermore, no positive effect on language has been reported in either form of physical activity. The aim of this study was to evaluate how two levels of PA (high or low) affect WM processing and how this, in turn, may affect morphosyntactic processing in older adults. Individuals with high PA (n = 18) had a higher WM load effect than those with low PA (n = 18), both behaviorally (greater differences between high and low WM loads in correct responses) and in terms of event-related potentials (only subjects with high PA showed LAN and P600b amplitude differences between high and low WM loads). These findings suggest that PA promotes cognitive strategies to face WM loads and morphosyntactic processing.

Intact reversed language-dominance but exaggerated cognate effects in reading aloud of language switches in bilingual Alzheimer's disease

OBJECTIVE

The current study investigated how Alzheimer's disease (AD) affects production of speech errors in reading-aloud of mixed-language passages with language switches on cognates (e.g., family/familia), noncognates (e.g., people/gente), and function words (the/la).

METHOD

Twelve Spanish-English bilinguals with AD and 22 controls read-aloud 8 paragraphs in 4 conditions: (a) English-default content switches, (b) English-default function switches, (c) Spanish-default content switches, and (d) Spanish-default function switches.

RESULTS

Reading elicited language intrusions (e.g., saying la instead of the), and several types of within-language errors (e.g., saying their instead of the). Reversed language-dominance effects were intact in AD; both patients and controls produced many intrusions on dominant language targets, and relatively fewer intrusions on nondominant language targets. The opposite held for within-language errors, which were more common with nondominant than dominant targets. Patients produced the most intrusion errors with cognate switch words (which best distinguished patients from controls in ROC curves of all speech error types), while controls had equal difficulty switching on cognate and function word targets.

CONCLUSIONS

Reversed language-dominance effects appear to illustrate automatic inhibitory control over the dominant language, but could instead reflect limited resources available for monitoring when completing a task in the nondominant language. The greater sensitivity of intrusion errors with cognate than with function word targets for distinguishing patients from controls implies that language control may be aided by relatively intact knowledge of grammatical constraints over code-switching in bilinguals with AD. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Communication behavior of cognitively impaired older inpatients : A new setting for validating the CODEM instrument

BACKGROUND AND OBJECTIVE

Acutely ill older patients with cognitive impairment represent a major subgroup in acute care hospitals. In this context, communication plays a crucial role for patients' well-being, healthcare decisions, and medical outcomes. As validated measures are lacking, we tested the psychometric properties of an observational instrument to assess Communication Behavior in Dementia (CODEM) in the acute care hospital setting. As a novel feature, we were also able to incorporate linguistic and social-contextual measures.

MATERIAL AND METHODS

Data were drawn from a cross-sectional mixed methods study that focused on the occurrence of elderspeak during care interactions in two German acute care hospitals. A total of 43 acutely ill older patients with severe cognitive impairment (CI group, Mage ± SD = 83.6 ± 5.7 years) and 50 without cognitive impairment (CU group, Mage ± SD = 82.1 ± 6.3 years) were observed by trained research assistants during a standardized interview situation and rated afterwards by use of CODEM.

RESULTS

Factor analysis supported the expected two-factor solution for the CI group, i.e., a verbal content and a nonverbal relationship aspect. Findings of the current study indicated sound psychometric properties of the CODEM instrument including internal consistency, convergent, divergent, and criterion validity.

CONCLUSION

CODEM represents a reliable and valid tool to examine the communication behavior of older patients with CI in the acute care hospital setting. Thus, CODEM might serve as an important instrument for researcher and healthcare professionals to describe and improve communication patterns in this environment.

Task difficulty modulates age-related differences in the behavioral and neural bases of language production

Older adults typically show decline in a variety of cognitive functions including inhibitory control and language production, with corresponding age-related increases in fMRI activation. However, it remains unclear whether such increases are compensatory or whether they reflect neural decline. One factor that may influence these brain-behavior relationships is difficulty. The current study investigated the effect of difficulty on age-related differences in the behavioral and neural bases of language production and inhibitory control using a phonological Go/No-Go picture naming task. Task demands were manipulated by varying the proportion of naming trials (Go trials) and inhibition trials (No-Go trials) across runs. All participants showed task-difficulty related declines in behavioral performance and increases in fMRI activation. Behaviorally, older adults were more sensitive to task difficulty, and elicited more fMRI activation than younger adults. Older adults were less neurally responsive to additional task demands (i.e., picture naming alone vs. Go/No-Go picture naming), but interestingly showed similar within-task increases as younger adults (e.g., Go Bias vs. No-Go Bias). Moreover, the relationships between fMRI activation and behavioral performance in older adults were multifaceted and the strength of these relations changed as a function of task difficulty. Specifically, activation in pre- and post- central gyri, right supramarginal and angular gyri was negatively correlated with naming reaction times, suggesting that activation in these regions may help mitigate age-related declines in language production. These findings are partially consistent with the CRUNCH model, highlighting the important influence of task difficulty on older adults' behavioral performance and their patterns of fMRI activation during language production.

Subjective rating scale for discourse: Evidence from the efficacy of subjective rating scale in amnestic mild cognitive impairments

In clinical settings, the language ability of patients with neurologic communication disorders have been measured by quantitative parameters such as the total number of words in dialogue and picture description tasks. However, this quantitative analysis requires a long period of time in order to analyze the quantitative parameters, and results can differ according to discourse tasks. The purposes of this study are to explore whether SR-D may predict the quantitative measures of discourse tasks. Forty patients with amnestic MCI and 40 normal elderly participated in the study. We gathered responses to 10 items regarding SR-D and analyzed the quantitative measures of narrative discourse through 3 discourse tasks (i.e, picture description, dialogue, procedural discourse). We found significant differences in MLTW, CIU, and SR-D scores between the 2 groups. In particular, 4 items were significantly correlated with the performance of MLTW and CIU. Sensitivity and specificity of these 4 items were 100% and 75%, respectively. In terms of economic opportunity costs, objective measures cannot be evaluated to be practical, since it is used in research rather than clinical diagnosis in general. Therefore, evaluation of discourse using a few items proven in its sensitivity and specificity could allow a wide use of such measure in not only research but also in clinical diagnosis. These findings suggest that subjective measures of narrative discourse may be valid with objective language tests to predict individual discourse performance.

An Empirical Analysis of Popular Press Claims Regarding Linguistic Change in President Donald J. Trump

Linguistic features of a person’s speech can change over time. It has been proposed that characteristics in the speech of President Donald J. Trump (DJT) have changed across time, though this claim has been based on subjective and anecdotal reports. A previous study of speech by Presidents of the United States identified an increase in the use of conversational fillers and non-specific nouns, and lower unique word counts, in the speech of President Ronald W. Reagan, but not in the speech of President George H.W. Bush. To empirically test claims of a systematic change in speech by DJT, we applied the same analysis by transcribing and analyzing publicly available Fox News interviews with DJT between 2011 and 2017. A regression analysis revealed a significant increase in the use of filler words by DJT over time. There was no significant change in numbers of unique words. The observed rise in filler words was significantly greater than filler-word change in President George H.W. Bush, and was not significantly different from the rise previously found in the speech of President Ronald W. Reagan. Identifying the reason for this linguistic change is not possible from speech samples alone, and the variables index linguistic change rather than being validated measures of change in cognitive ability. Nonetheless, features of the data such as the trajectory starting years before announcement of candidacy rule-out several potential explanations. To summarize, we find statistical evidence to support suggestions that speech by DJT has changed over time.

Identification of Mild Cognitive Impairment From Speech in Swedish Using Deep Sequential Neural Networks

While people with mild cognitive impairment (MCI) portray noticeably incipient memory difficulty in remembering events and situations along with problems in decision making, planning, and finding their way in familiar environments, detailed neuropsychological assessments also indicate deficits in language performance. To this day, there is no cure for dementia but early-stage treatment can delay the progression of MCI; thus, the development of valid tools for identifying early cognitive changes is of great importance. In this study, we provide an automated machine learning method, using Deep Neural Network Architectures, that aims to identify MCI. Speech materials were obtained using a reading task during evaluation sessions, as part of the Gothenburg MCI research study. Measures of vowel duration, vowel formants (F1 to F5), and fundamental frequency were calculated from speech signals. To learn the acoustic characteristics associated with MCI vs. healthy controls, we have trained and evaluated ten Deep Neural Network Architectures and measured how accurately they can diagnose participants that are unknown to the model. We evaluated the models using two evaluation tasks: a 5-fold crossvalidation and by splitting the data into 90% training and 10% evaluation set. The findings suggest first, that the acoustic features provide significant information for the identification of MCI; second, the best Deep Neural Network Architectures can classify MCI and healthy controls with high classification accuracy (M = 83%); and third, the model has the potential to offer higher accuracy than 84% if trained with more data (cf., SD≈15%). The Deep Neural Network Architecture proposed here constitutes a method that contributes to the early diagnosis of cognitive decline, quantify the progression of the condition, and enable suitable therapeutics.

Curvilinear Association Between Language Disfluency and FMR1 CGG Repeat Size Across the Normal, Intermediate, and Premutation Range

Historically, investigations of FMR1 have focused almost exclusively on the clinical effects of CGG expansion within the categories of the premutation (55-200 CGG repeats) and fragile X syndrome (>200 CGG repeats). However, emerging evidence suggests that CGG-dependent phenotypes may occur across allele sizes traditionally considered within the "normal" range. This study adopted an individual-differences approach to determine the association between language production ability and CGG repeat length across the full range of normal, intermediate, and premutation alleles. Participants included 61 adult women with CGG repeats within the premutation (n = 37), intermediate (i.e., 41-54 repeats; n = 2), or normal (i.e., 6-40 repeats; n = 22) ranges. All participants were the biological mothers of a child with a developmental disorder, to control for the potential effects of parenting stress. Language samples were collected and the frequency of language disfluencies (i.e., interruptions in the flow of speech) served as an index of language production skills. Verbal inhibition skills, measured with the Hayling Sentence Completion Test, were also measured and examined as a correlate of language disfluency, consistent with theoretical work linking language disfluency with inhibitory deficits (i.e., the Inhibition Deficit Hypothesis). Blood samples were collected to determine FMR1 CGG repeat size. A general linear model tested CGG repeat size of the larger allele (allele-2) as the primary predictor of language disfluency, covarying for education level, IQ, age, and CGG repeats on the other allele. A robust curvilinear association between CGG length and language disfluency was detected, where low-normal (∼ <25 repeats) and mid-premutation alleles (∼90-110 repeats) were linked with higher rates of disfluency. Disfluency was not associated with inhibition deficits, which challenges prior theoretical work and suggests that a primary language deficit could account for elevated language disfluency in FMR1-associated conditions. Findings suggest CGG-dependent variation in language production ability, which was evident across individuals with and without CGG expansions on FMR1.

Effects of Age and Working Memory Load on Syntactic Processing: An Event-Related Potential Study

Cognitive changes in aging include working memory (WM) decline, which may hamper language comprehension. An increase in WM demands in older adults would probably provoke a poorer sentence processing performance in this age group. A way to increase the WM load is to separate two lexical units in an agreement relation (i.e., adjective and noun), in a given sentence. To test this hypothesis, event-related potentials (ERPs) were collected from Spanish speakers (30 older adults, mean age = 66.06 years old; and 30 young adults, mean age = 25.7 years old) who read sentences to detect grammatical errors. The sentences varied with regard to (1) the gender agreement of the noun and adjective, where the gender of the adjective either agreed or disagreed with the noun, and (2) the WM load (i.e., the number of words between the noun and adjective in the sentence). No significant behavioral differences between groups were observed in the accuracy of the response, but older adults showed longer reaction times regardless of WM load condition. Compared with young participants, older adults showed a different pattern of ERP components characterized by smaller amplitudes of LAN, P600a, and P600b effects when the WM load was increased. A smaller LAN effect probably reflects greater difficulties in processing the morpho-syntactic features of the sentence, while smaller P600a and P600b effects could be related to difficulties in recovering and mapping all sentence constituents. We concluded that the ERP pattern in older adults showed subtle problems in syntactic processing when the WM load was increased, which was not sufficient to affect response accuracy but was only observed to result in a longer reaction time.

Declines in Connected Language Are Associated with Very Early Mild Cognitive Impairment: Results from the Wisconsin Registry for Alzheimer's Prevention

Changes to everyday spoken language ("connected language") are evident in persons with AD dementia, yet little is known about when these changes are first detectable on the continuum of cognitive decline. The aim of this study was to determine if participants with very early, subclinical memory declines were also showing declines in connected language. We analyzed connected language samples obtained from a simple picture description task at two time points in 264 participants from the Wisconsin Registry for Alzheimer's Prevention (WRAP). In parallel, participants were classified as either "Cognitively Healthy" or "Early Mild Cognitive Impairment" based on longitudinal neuropsychological test performance. Linear mixed effects models were used to analyze language parameters that were extracted from the connected language samples using automated feature extraction. Participants with eMCI status declined faster in features of speech fluency and semantic content than those who were cognitively stable. Measures of lexical diversity and grammatical complexity were not associated with eMCI status in this group. These findings provide novel insights about the relationship between cognitive decline and everyday language, using a quick, inexpensive, and performance-based method.

Tracking discourse complexity preceding Alzheimer's disease diagnosis: a case study comparing the press conferences of Presidents Ronald Reagan and George Herbert Walker Bush

Changes in some lexical features of language have been associated with the onset and progression of Alzheimer's disease. Here we describe a method to extract key features from discourse transcripts, which we evaluated on non-scripted news conferences from President Ronald Reagan, who was diagnosed with Alzheimer's disease in 1994, and President George Herbert Walker Bush, who has no known diagnosis of Alzheimer's disease. Key word counts previously associated with cognitive decline in Alzheimer's disease were extracted and regression analyses were conducted. President Reagan showed a significant reduction in the number of unique words over time and a significant increase in conversational fillers and non-specific nouns over time. There was no significant trend in these features for President Bush.

Age-Related Changes in Predictive Capacity Versus Internal Model Adaptability: Electrophysiological Evidence that Individual Differences Outweigh Effects of Age

Hierarchical predictive coding has been identified as a possible unifying principle of brain function, and recent work in cognitive neuroscience has examined how it may be affected by age–related changes. Using language comprehension as a test case, the present study aimed to dissociate age-related changes in prediction generation versus internal model adaptation following a prediction error. Event-related brain potentials (ERPs) were measured in a group of older adults (60–81 years; n = 40) as they read sentences of the form “The opposite of black is white/yellow/nice.” Replicating previous work in young adults, results showed a target-related P300 for the expected antonym (“white”; an effect assumed to reflect a prediction match), and a graded N400 effect for the two incongruous conditions (i.e. a larger N400 amplitude for the incongruous continuation not related to the expected antonym, “nice,” versus the incongruous associated condition, “yellow”). These effects were followed by a late positivity, again with a larger amplitude in the incongruous non-associated versus incongruous associated condition. Analyses using linear mixed-effects models showed that the target-related P300 effect and the N400 effect for the incongruous non-associated condition were both modulated by age, thus suggesting that age-related changes affect both prediction generation and model adaptation. However, effects of age were outweighed by the interindividual variability of ERP responses, as reflected in the high proportion of variance captured by the inclusion of by-condition random slopes for participants and items. We thus argue that – at both a neurophysiological and a functional level – the notion of general differences between language processing in young and older adults may only be of limited use, and that future research should seek to better understand the causes of interindividual variability in the ERP responses of older adults and its relation to cognitive performance.

Proofreading in Young and Older Adults: The Effect of Error Category and Comprehension Difficulty

Proofreading text relies on stored knowledge, language processing, and attentional resources. Age differentially affects these constituent abilities: while older adults maintain word knowledge and most aspects of language comprehension, language production and attention capacity are impaired with age. Research with young adults demonstrates that proofreading is more attentionally-demanding for contextual errors which require integration across multiple words compared to noncontextual errors which occur within a single word. Proofreading is also more attentionally-demanding for text which is more difficult to comprehend compared to easier text. Older adults may therefore be impaired at aspects of proofreading which require production, contextual errors, or more difficult text. The current study tested these possibilities using a naturalistic proofreading task. Twenty-four young and 24 older adults proofread noncontextual (spelling) and contextual (grammar or meaning) errors in passages that were easier or more difficult to comprehend. Older adults were preserved at proofreading spelling errors, but were impaired relative to young adults when proofreading grammar or meaning errors, especially for difficult passages. Additionally, older adults were relatively spared at detecting errors compared to correcting spelling errors, in keeping with previous research. Age differences were not attributable to individual differences in vocabulary knowledge or self-reported spelling ability.

Superior longitudinal fasciculus and language functioning in healthy aging

Structural deterioration of brain tissue in older adults is thought to be responsible for the majority of age-related cognitive decline. Disruption of widespread cortical networks due to a loss of axonal integrity may also play an important role. Research examining correlations between structural change and functional decline has focused heavily on working memory, processing speed, and executive processes while other aspects of cognition, such as language functioning, have received less attention. The current study aimed to determine whether age-related changes in the superior longitudinal fasciculus (SLF), are responsible for the deterioration in language functioning associated with age. Subjects included 112 right-handed volunteers (ages 19-76). For each subject, the SLF of the left hemisphere was reconstructed from diffusion tensor images (DTI). Mean fractional anisotropy (FA) values were extracted from parietal (SLFp) and temporal (SLFt) bundles. Language functioning was measured using the Peabody Picture Vocabulary Test (PPVT), Boston Naming Test (BNT), Controlled Oral Word Association Test (COWAT), and Semantic Fluency Test (SFT). Regression analyses revealed that males and females showed a different pattern of decline in FA across adulthood. For males, greater SLFt FA was significantly associated with increased COWAT performance, and there was a positive relationship between both age and SLFp FA with BNT scores. In females, greater SLFp FA was related to lower COWAT performance. Taken together, the results suggest that white matter integrity of the SLF follows a different pattern of decline in adulthood for males and females, and this decline differentially affects language functioning.

Different effects of dual task demands on the speech of young and older adults

Young and older adults provided language samples in response to elicitation questions while concurrently performing 3 different tasks. The language samples were scored on three dimensions: fluency, grammatical complexity, and content. Previous research had suggested the hypothesis that the restricted speech register of older adults is buffered from the costs of dual task demands. This hypothesis was tested by comparing language samples collected during a baseline condition with those produced while the participants were performing the concurrent tasks. The results indicate that young and older adults adopt different strategies when confronted with dual task demands. Young adults shift to a restricted speech register when confronted with dual task demands. Older adults, who were already using a restricted speech register, became less fluent although the grammatical complexity and informational content of their speech was preserved. Hence, some but not all aspects of older adults' speech are buffered from dual task demands.

Characterizing cognitive aging in humans with links to animal models

With the population of older adults expected to grow rapidly over the next two decades, it has become increasingly important to advance research efforts to elucidate the mechanisms associated with cognitive aging, with the ultimate goal of developing effective interventions and prevention therapies. Although there has been a vast research literature on the use of cognitive tests to evaluate the effects of aging and age-related neurodegenerative disease, the need for a set of standardized measures to characterize the cognitive profiles specific to healthy aging has been widely recognized. Here we present a review of selected methods and approaches that have been applied in human research studies to evaluate the effects of aging on cognition, including executive function, memory, processing speed, language, and visuospatial function. The effects of healthy aging on each of these cognitive domains are discussed with examples from cognitive/experimental and clinical/neuropsychological approaches. Further, we consider those measures that have clear conceptual and methodological links to tasks currently in use for non-human animal studies of aging, as well as those that have the potential for translation to animal aging research. Having a complementary set of measures to assess the cognitive profiles of healthy aging across species provides a unique opportunity to enhance research efforts for cross-sectional, longitudinal, and intervention studies of cognitive aging. Taking a cross-species, translational approach will help to advance cognitive aging research, leading to a greater understanding of associated neurobiological mechanisms with the potential for developing effective interventions and prevention therapies for age-related cognitive decline.

The effect of aging on the neural correlates of phonological word retrieval

Age has a differential effect on cognition, with word retrieval being one of the cognitive domains most affected by aging. This study examined the functional and structural neural correlates of phonological word retrieval in younger and older adults using word and picture rhyme judgment tasks. Although the behavioral performance in the fMRI task was similar for the two age groups, the older adults had increased activation in the right pars triangularis across tasks and in the right pars orbitalis for the word task only. Increased activation together with preserved performance in the older participants would suggest that increased activation was related to compensatory processing. We validated this hypothesis by showing that right pars triangularis activation during correct rhyme judgments was highest in participants who made overall more errors, therefore being most error-prone. Our findings demonstrate that the effect of aging differ in adjacent but distinct right inferior frontal regions. The differential effect of age on word and picture tasks also provides new clues to the level of processing that is most affected by age in speech production tasks. Specifically, we suggest that right inferior frontal activation in older participants is needed to inhibit errors.

Idea density measured in late life predicts subsequent cognitive trajectories: implications for the measurement of cognitive reserve

OBJECTIVE

The Nun Study showed that lower linguistic ability in young adulthood, measured by idea density (ID), increased the risk of dementia in late life. The present study examined whether ID measured in late life continues to predict the trajectory of cognitive change.

METHOD

ID was measured in 81 older adults who were followed longitudinally for an average of 4.3 years. Changes in global cognition and 4 specific neuropsychological domains (episodic memory, semantic memory, spatial abilities, and executive function) were examined as outcomes. Separate random effects models tested the effect of ID on longitudinal change in outcomes, adjusted for age and education.

RESULTS

Lower ID was associated with greater subsequent decline in global cognition, semantic memory, episodic memory, and spatial abilities. When analysis was restricted to only participants without dementia at the time ID was collected, results were similar.

DISCUSSION

Linguistic ability in young adulthood, as measured by ID, has been previously proposed as an index of neurocognitive development and/or cognitive reserve. The present study provides evidence that even when ID is measured in old age, it continues to be associated with subsequent cognitive decline and as such may continue to provide a marker of cognitive reserve.

The effects of varying task priorities on language production by young and older adults

The present study compared how varying task priorities affected young and older adults' language production. Both young and older adults responded to monetary incentives to vary their performance when simultaneously talking and tracking a pursuit rotor. Tracking performance improved when they were rewarded for tracking and declined when they were rewarded for talking. Both young and older adults also spoke more slowly when rewarded for tracking and more rapidly when rewarded for talking. Young produced less complex sentences when rewarded for tracking and produced more complex sentences when rewarded for talking. However, older adults did not vary their grammatical complexity as a function of monetary incentives. These results are consistent with prior studies suggesting that older adults use a simplified speech register in response to dual-task demands.

A corpus analysis of patterns of age-related change in conversational speech

Conversational speech from over 300 speakers from 17 to 68 years of age was analyzed for age-related changes in the timing and content of spoken language production. Overall, several relationships between the lexical content, timing, and fluency of speech emerged, such that more novel and lower frequency words were associated with slower speech and higher levels of disfluencies. Speaker age was associated with slower speech and more filled pauses, particularly those associated with lexical selection. Increasing age, however, was also associated with longer utterances and greater lexical diversity. On balance, these analyses present a picture of age-related changes in speech performance that largely support data obtained from controlled laboratory studies. However, particular patterns of age-related change may be moderated in conversational situations.

Propositional density and cognitive function in later life: findings from the Precursors Study

OBJECTIVES

We used longitudinal data from the Johns Hopkins Precursors Study to test the hypothesis that written propositional density measured early in life is lower for people who develop dementia categorized as Alzheimer's disease (AD). This association was reported in 1996 for the Nun Study, and the Precursors Study offered an unprecedented chance to reexamine it among respondents with different gender, education, and occupation profiles.

METHODS

Eighteen individuals classified as AD patients (average age at diagnosis: 74) were assigned 2 sex-and-age matched controls, and propositional density in medical school admission essays (average age at writing: 22) was assessed via Computerized Propositional Idea Density Rater 3 linguistic analysis software. Adjusted odds ratios (ORs) for the matched case-control study were calculated using conditional (fixed-effects) logistic regression.

RESULTS

Mean propositional density is lower for cases than for controls (4.70 vs. 4.99 propositions per 10 words, 1-sided p = .01). Higher propositional density substantially lowers the odds of AD (OR = 0.16, 95% confidence interval = 0.03-0.90, 1-sided p = .02).

DISCUSSION

Propositional density scores in writing samples from early adulthood appear to predict AD in later life for men as well as women. Studies of cognition across the life course might beneficially incorporate propositional density as a potential marker of cognitive reserve.

An item response theory analysis of DSM-IV personality disorder criteria across younger and older age groups

Many of the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV; American Psychiatric Association, 1994) personality disorder (PD) diagnostic criteria focus on a younger social and occupational context. The absence of age-appropriate criteria for older adults forces researchers and clinicians to draw conclusions based on existing criteria, which are likely inadequate. To explore which DSM-IV PD criteria contain age group measurement bias, the authors report 2 analyses of data on nearly 37,000 participants, ages 18-98 years, taken from a public data set that includes 7 of the 10 PDs (antisocial, avoidant, dependent, histrionic, obsessive-compulsive, paranoid, and schizoid). The 1st analysis revealed that older age groups tend to endorse fewer PD criteria than younger age groups. The 2nd analysis revealed that 29% of the criteria contain measurement bias. Although the latent variable structure for each PD was quite similar across younger and older age groups, some individual criteria were differentially endorsed by younger and older adults with equivalent PD pathology. The presence of measurement bias for these criteria raises questions concerning the assessment of PDs in older adults and the interpretation of existing data.

Neuropsychological differences between frontotemporal dementia and Alzheimer's disease: a review

This paper surveys the similarities and differences between frontotemporal dementia (FTD) and Alzheimer's disease (AD). The review covers findings primarily from neuropsychological studies on memory, language, attention/executive function, and visuospatial abilities. However, neuropsychiatric and neuroimaging data are also briefly discussed. Distinguishing features of both FTD and AD are described in order to present a comprehensive clinical picture of these dementing diseases, which is essential for the process of differential diagnosis. The cause of specific cognitive deficits is also considered. Our comprehensive review of the empirical literature reveals that AD is characterized by early memory loss and visuospatial problems, while among the main features of FTD are behavioral abnormalities and executive dysfunctions.