David J Libon

Drexel University, Filadelfia, Pennsylvania, United States

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Publications (148)594.62 Total impact

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    ABSTRACT: Analysis sought to determine whether Wechsler Memory Scale-Logical Memory (LM)-correct responses and errors were related to magnetic resonance imaging (MRI) brain volume measurements. The LM immediate (LM-I) and LM delay (LM-D) free recall correct responses and related and unrelated errors were scored. Principal components analysis yielded a 3-factor solution: LM-I and LM-D correct responses, LM-I and LM-D-unrelated errors, and LM-I/-D-related errors. The MRI total cerebral brain volume, frontal brain volume, temporal horn volume (THV), and white matter hyperintensities volume (WMHIV) were obtained. Increasing THV (suggesting greater regional atrophy) was associated with lower scores on the LM-correct responses factor. Extensive WMHIV was associated with higher scores on the LM-related errors factor. These results suggest that LM-correct responses could relate to emerging brain alterations. Longitudinal research might enhance the sensitivity of this test to identify preclinical impairment and persons at risk of mild cognitive impairment and dementia. © The Author(s) 2015.
    American Journal of Alzheimer s Disease and Other Dementias 03/2015; DOI:10.1177/1533317515577184 · 1.43 Impact Factor
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    ABSTRACT: Objective: Prior research has shown that individuals with Parkinson's disease dementia (PDD) show a different pattern of error types on everyday tasks compared with individuals with Alzheimer's disease (AD). This study evaluated whether these groups would respond differently to cues designed to remind participants of task goals and improve performance of everyday tasks (i.e., goal cues). Method: Participants with PDD (n = 20) and AD (n = 20), and a comparison group of individuals with Parkinson's disease and no dementia (n = 20), were administered performance-based tasks of everyday functioning that allowed for the quantification of errors before and after the presentation of goal cues. Results: AD participants showed a significantly greater response to the goal cues as compared with individuals with PDD. The goal cues facilitated the completion of task goals but did not promote error correction (i.e., the undoing of errors that had been made earlier during the task). Conclusions: Not all dementia patients respond similarly to cues designed to improve everyday functioning. Understanding patients' specific form of everyday action impairment is crucial for developing individualized interventions that target specific functional deficits. (PsycINFO Database Record (c) 2014 APA, all rights reserved).
    Neuropsychology 12/2014; DOI:10.1037/neu0000167 · 3.43 Impact Factor
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    ABSTRACT: The aim of the present study was to assess the validity of a 12-word Czech version of the Philadelphia (repeatable) Verbal Learning Test [czP(r)VLT-12]. The construction of the czP(r)VLT-12 was modeled after the California Verbal Learning Test (CVLT) and the nine-word Philadelphia (repeatable) Verbal Learning Test [P(r)VLT]. The czP(r)VLT-12 was constructed from a large corpus of old (60-74) and very old (75-96) Czech adults (n = 540). Participants met strict inclusion criteria for the absence of any active or past neurodegenerative disorders and performed within normal limits on other neuropsychological measures. Principal component analysis (PCA) and correlations between czP(r)VLT-12 factor structure and other memory tests were conducted. The czP(r)VLT-12 produced a four-factor solution, accounting for 70.90% of variance, with factors related to: (1) recall, (2) extra-list intrusion errors/recognition foils, (3) interference, and (4) acquisition rate; a solution similar to the CVLT and P(r)VLT. Increasing age resulted in a decline in most czP(r)VLT-12 indices, women outperformed men, and higher education led to higher scores. Memory performance in normal aging did not correlate with instrumental activities of daily living. Low, but significant, correlations were seen with other tests of cognitive performance (divergent validity). Appendices are available that provide normed percentile estimates of individual czP(r)VLT-12 performance stratified by age, education, and gender. In accordance with previous studies, these results demonstrate the usefulness of czP(r)VLT-12 in assessing declarative memory in older adults.
    The Clinical Neuropsychologist 09/2014; DOI:10.1080/13854046.2014.952666 · 1.58 Impact Factor
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    ABSTRACT: Psychomotor slowing has been documented in depression. The digital Clock Drawing Test (dCDT) provides: (i) a novel technique to assess both cognitive and motor aspects of psychomotor speed within the same task and (ii) the potential to uncover subtleties of behavior not previously detected with non-digitized modes of data collection. Using digitized pen technology in 106 participants grouped by Age (younger/older) and Affect (euthymic/unmedicated depressed), we recorded cognitive and motor output by capturing how the clock is drawn rather than focusing on the final product. We divided time to completion (TTC) for Command and Copy conditions of the dCDT into metrics of percent of drawing (%Ink) versus non-drawing (%Think) time. We also obtained composite Z-scores of cognition, including attention/information processing (AIP), to explore associations of %Ink and %Think times to cognitive and motor performance. Despite equivalent TTC, %Ink and %Think Command times (Copy n.s.) were significant (AgeXAffect interaction: p=.03)-younger depressed spent a smaller proportion of time drawing relative to thinking compared to the older depressed group. Command %Think time negatively correlated with AIP in the older depressed group (r=-.46; p=.02). Copy %Think time negatively correlated with AIP in the younger depressed (r=-.47; p=.03) and older euthymic groups (r=-.51; p=.01). The dCDT differentiated aspects of psychomotor slowing in depression regardless of age, while dCDT/cognitive associates for younger adults with depression mimicked patterns of older euthymics. (JINS, 2014, 20, 1-9).
    Journal of the International Neuropsychological Society 09/2014; 20(9):1-9. DOI:10.1017/S1355617714000757 · 3.01 Impact Factor
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    ABSTRACT: Background: Epidemiologic autopsy studies show mixed Alzheimer's disease (AD)/vascular pathology in many patients. Moreover, clinical research shows that it is not uncommon for AD and vascular dementia (VaD) patients to be equally impaired on memory, executive, or other neurocognitive tests. However, this clinical heterogeneity has not been incorporated into the new diagnostic criteria for AD (Dubois et al., 2010; McKhann et al., 2011). Objective: The current research applied Latent Class Analysis (LCA) to a protocol of six neuropsychological parameters to identify phenotypic subtypes from a large group of AD/VaD participants. Follow-up analyses examined difference between groups on neuroradiological parameters and neuropsychological measures of process and errors. Methods: 223 AD/VaD patients were administered a comprehensive neuropsychological protocol. Measures of whole brain and hippocampal volume were available for a portion of the sample (n = 76). Results: LCA identified four distinct groups: moderate/mixed dementia (n = 54; 24.21%), mild/mixed dementia (n = 91; 40.80%); dysexecutive (n = 49, 21.97%), and amnestic (n = 29, 13.00%). Follow-up analyses comparing the groups on neuropsychological process and error scores showed that the dysexecutive group exhibited difficulty sustaining mental set. The moderate/mixed group evidenced pronounced impairment on tests of lexical retrieval/naming along with significant amnesia. Amnestic patients also presented with gross amnesia, but showed relative sparing on other neuropsychological measures. Mild/mixed patients exhibited milder memory deficits that were intermediary between the amnestic and moderate/mixed groups. Conclusions: There are distinct neuropsychological profiles in patients independent of clinical diagnosis, suggesting that the two are not wholly separate and that this information should be integrated into new AD diagnostic paradigms.
    Journal of Alzheimer's disease: JAD 07/2014; 42(3). DOI:10.3233/JAD-132147 · 3.61 Impact Factor
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    Alzheimer's and Dementia 07/2014; 10(4):P503. DOI:10.1016/j.jalz.2014.05.763 · 17.47 Impact Factor
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    Alzheimer's and Dementia 07/2014; 10(4):P436-P437. DOI:10.1016/j.jalz.2014.05.580 · 17.47 Impact Factor
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    Alzheimer's and Dementia 07/2014; 10(4):P310. DOI:10.1016/j.jalz.2014.05.252 · 17.47 Impact Factor
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    Alzheimer's and Dementia 07/2014; 10(4):P275. DOI:10.1016/j.jalz.2014.04.451 · 17.47 Impact Factor
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    Alzheimer's and Dementia 07/2014; 10(4):P568. DOI:10.1016/j.jalz.2014.05.929 · 17.47 Impact Factor
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    ABSTRACT: We compared two methods of diagnosing mild cognitive impairment (MCI): conventional Petersen/Winblad criteria as operationalized by the Alzheimer's Disease Neuroimaging Initiative (ADNI) and an actuarial neuropsychological method put forward by Jak and Bondi designed to balance sensitivity and reliability. 1,150 ADNI participants were diagnosed at baseline as cognitively normal (CN) or MCI via ADNI criteria (MCI: n = 846; CN: n = 304) or Jak/Bondi criteria (MCI: n = 401; CN: n = 749), and the two MCI samples were submitted to cluster and discriminant function analyses. Resulting cluster groups were then compared and further examined for APOE allelic frequencies, cerebrospinal fluid (CSF) Alzheimer's disease (AD) biomarker levels, and clinical outcomes. Results revealed that both criteria produced a mildly impaired Amnestic subtype and a more severely impaired Dysexecutive/Mixed subtype. The neuropsychological Jak/Bondi criteria uniquely yielded a third Impaired Language subtype, whereas conventional Petersen/Winblad ADNI criteria produced a third subtype comprising nearly one-third of the sample that performed within normal limits across the cognitive measures, suggesting this method's susceptibility to false positive diagnoses. MCI participants diagnosed via neuropsychological criteria yielded dissociable cognitive phenotypes, significant CSF AD biomarker associations, more stable diagnoses, and identified greater percentages of participants who progressed to dementia than conventional MCI diagnostic criteria. Importantly, the actuarial neuropsychological method did not produce a subtype that performed within normal limits on the cognitive testing, unlike the conventional diagnostic method. Findings support the need for refinement of MCI diagnoses to incorporate more comprehensive neuropsychological methods, with resulting gains in empirical characterization of specific cognitive phenotypes, biomarker associations, stability of diagnoses, and prediction of progression. Refinement of MCI diagnostic methods may also yield gains in biomarker and clinical trial study findings because of improvements in sample compositions of 'true positive' cases and removal of 'false positive' cases.
    Journal of Alzheimer's disease: JAD 05/2014; 42(1). DOI:10.3233/JAD-140276 · 3.61 Impact Factor
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    ABSTRACT: Background We assessed whether mild cognitive impairment (MCI) subtypes could be empirically derived within the Alzheimer's Disease Neuroimaging Initiative (ADNI) MCI cohort and examined associated biomarkers and clinical outcomes. Methods Cluster analysis was performed on neuropsychological data from 825 MCI ADNI participants. Results Four subtypes emerged: (1) dysnomic (n = 153), (2) dysexecutive (n = 102), (3) amnestic (n = 288), and (4) cluster-derived normal (n = 282) who performed within normal limits on cognitive testing. The cluster-derived normal group had significantly fewer APOE ε4 carriers and fewer who progressed to dementia compared with the other subtypes; they also evidenced cerebrospinal fluid Alzheimer's disease biomarker profiles that did not differ from the normative reference group. Conclusions Identification of empirically derived MCI subtypes demonstrates heterogeneity in MCI cognitive profiles that is not captured by conventional criteria. The large cluster-derived normal group suggests that conventional diagnostic criteria are susceptible to false-positive errors, with the result that prior MCI studies may be diluting important biomarker relationships.
    Alzheimer's and Dementia 05/2014; DOI:10.1016/j.jalz.2014.03.005 · 17.47 Impact Factor
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    ABSTRACT: Total knee arthroplasty improves quality of life but is associated with postoperative cognitive dysfunction in older adults. This prospective longitudinal pilot study with a parallel control group tested the hypotheses that (1) nondemented adults would exhibit primary memory and executive difficulties after total knee arthroplasty, and (2) reduced preoperative hippocampus/entorhinal volume would predict postoperative memory change, whereas preoperative leukoaraiosis and lacunae volumes would predict postoperative executive dysfunction. Surgery (n = 40) and age-education-matched controls with osteoarthritis (n = 15) completed pre- and postoperative (3 weeks, 3 months, and 1 yr) memory and cognitive testing. Hypothesized brain regions of interest were measured in patients completing preoperative magnetic resonance scans (surgery, n = 31; control, n = 12). Analyses used reliable change methods to identify the frequency of cognitive change at each time point. The incidence of postoperative memory difficulties was shown with delay test indices (i.e., story memory test: 3 weeks = 17%, 3 months = 25%, 1 yr = 9%). Postoperative executive difficulty with measures of inhibitory function (i.e., Stroop Color Word: 3 weeks = 21%, 3 months = 22%, 1 yr = 9%). Hierarchical regression analysis assessing the predictive interaction of group (surgery, control) and preoperative neuroanatomical structures on decline showed that greater preoperative volumes of leukoaraiosis/lacunae were significantly contributed to postoperative executive (inhibitory) declines. This pilot study suggests that executive and memory declines occur in nondemented adults undergoing orthopedic surgery. Severity of preoperative cerebrovascular disease may be relevant for understanding executive decline, in particular.
    Anesthesiology 03/2014; 120(3):601-13. DOI:10.1097/ALN.0000000000000080 · 6.17 Impact Factor
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    ABSTRACT: Cognitive impairment in amyotrophic lateral sclerosis (ALS) is associated with cortical changes beyond the motor cortex. The overall goal of this project is to determine if task induced hemodynamic changes detected by functional near infrared (fNIR) spectroscopy from the anterior prefrontal cortex (PFC) has discriminant validity across ALS (n = 17) patients and matching healthy (n = 17) controls. The experimental protocol was composed of the King-Devick Test, the Number Interference Test and a Continuous Performance Test targeting a range of cognitive domains including sustained attention and executive function. Results indicate that fNIR measures provided significant differences between ALS and healthy controls in all three tasks providing an additional metric for the assessment of cognitive decline. Although this is a pilot study, given the safe, wearable and realworld validity of fNIR, these results may set the foundation for the use of fNIR as a clinical tool in monitoring progression of neurocognitive decline in a simple, less invasive and objective manner than allowed by current imaging technology.
    02/2014; 3(1). DOI:10.1166/jnsne.2014.1095
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    ABSTRACT: Background / Purpose: Recent evidence suggests that deficits in frontally-mediated executive skills occur in up to 50% of individuals with Amyotrophic Lateral Sclerosis (ALS). Functional Near Infrared Spectroscopy (fNIR) is a safe, noninvasive, affordable, and portable neuroimaging technology that may be useful in detecting pathophysiologic changes in the frontal lobe that may correlate with cognitive involvement. The objective of this study was to examine and compare hemodynamic changes detected by fNIR during challenging cognitive tasks in individuals with ALS and healthy controls. Main conclusion: Differences in oxygen utilization between ALS and healthy controls were noted despite the lack of gross cognitive impairment in the ALS group, implying that fNIR may be more sensitive to early cognitive changes than neuropsychological testing alone. Correlations between fNIR measures and respiratory, executive, and behavioral subscales also imply that fNIR is sensitive to changes in these at-risk areas.
    International Symposium on Amyotrophic Lateral Sclerosis and Motor Neurone Disease 2013; 01/2014
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    ABSTRACT: Mild cognitive impairment (MCI) is a dynamic state between normal cognition and dementia, where interventions can be taken to stop or delay the progression to dementia. It is broadly of 2 types-amnestic, where memory loss is the chief concern and nonamnestic, where it is not. One variant of nonamnestic, dysexecutive, being more prevalent is sometimes known as a separate subtype by itself. Diagnosis of MCI is mostly clinical and is aided by various scales and neuropsychological testing. Functional imaging studies help in early detection and is superior to biomarkers or structural magnetic resonance imaging. Although there is no evidence supporting any pharmacological intervention, cognitive rehabilitation, memory training, and caregiver support play a strong role in limiting and sometimes reversing the ongoing cognitive decline. As the spectrum of MCI is heterogeneous, making the right diagnosis can be a challenging; hence, we need a systematic yet cost-effective algorithm for the timely management of MCI.
    American Journal of Alzheimer s Disease and Other Dementias 12/2013; 29(4). DOI:10.1177/1533317513517040 · 1.43 Impact Factor
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    ABSTRACT: Mild functional difficulties have been associated with early cognitive decline in older adults and increased risk for conversion to dementia in mild cognitive impairment, but our understanding of this decline has been limited by a dearth of objective methods. This study evaluated the reliability and validity of a new system to code subtle errors on an established performance-based measure of everyday action and described preliminary findings within the context of a theoretical model of action disruption. Here 45 older adults completed the Naturalistic Action Test (NAT) and neuropsychological measures. NAT performance was coded for overt errors, and subtle action difficulties were scored using a novel coding system. An inter-rater reliability coefficient was calculated. Validity of the coding system was assessed using a repeated-measures ANOVA with NAT task (simple versus complex) and error type (overt versus subtle) as within-group factors. Correlation/regression analyses were conducted among overt NAT errors, subtle NAT errors, and neuropsychological variables. The coding of subtle action errors was reliable and valid, and episodic memory breakdown predicted subtle action disruption. Results suggest that the NAT can be useful in objectively assessing subtle functional decline. Treatments targeting episodic memory may be most effective in addressing early functional impairment in older age.
    The Clinical Neuropsychologist 11/2013; 28(1). DOI:10.1080/13854046.2013.852624 · 1.58 Impact Factor
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    ABSTRACT: The everyday, functional impairments associated with dementia remain poorly understood from a neuropsychological perspective. This study investigated relations between brain structure volumes and two measures of everyday action-caregiver questionnaire and direct assessment-in 57 participants with dementia. Results showed that caregiver ratings reflecting more functional impairment were strongly associated with smaller volumes of deep white matter. Direct assessment of everyday task performance in a subsample revealed relations between unique neurological substrates and discrete everyday action error types. Findings emphasize differences in functional assessment methods and highlight the role of white matter in functional deficits in dementia.
    Journal of Clinical and Experimental Neuropsychology 10/2013; DOI:10.1080/13803395.2013.844773 · 2.16 Impact Factor
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    ABSTRACT: This study establishes that sparse canonical correlation analysis (SCCAN) identifies generalizable, structural MRI-derived cortical networks that relate to five distinct categories of cognition. We obtain multivariate psychometrics from the domain-specific sub-scales of the Philadelphia Brief Assessment of Cognition (PBAC). By using a training and separate testing stage, we find that PBAC-defined cognitive domains of language, visuospatial functioning, episodic memory, executive control, and social functioning correlate with unique and distributed areas of gray matter (GM). In contrast, a parallel univariate framework fails to identify, from the training data, regions that are also significant in the left-out test dataset. The cohort includes164 patients with Alzheimer's disease, behavioral-variant frontotemporal dementia, semantic variant primary progressive aphasia, non-fluent/agrammatic primary progressive aphasia, or corticobasal syndrome. The analysis is implemented with open-source software for which we provide examples in the text. In conclusion, we show that multivariate techniques identify biologically-plausible brain regions supporting specific cognitive domains. The findings are identified in training data and confirmedin test data.
    NeuroImage 10/2013; 84. DOI:10.1016/j.neuroimage.2013.09.048 · 6.13 Impact Factor

Publication Stats

2k Citations
594.62 Total Impact Points

Institutions

  • 1991–2014
    • Drexel University
      • • Department of Neurology
      • • Department of Psychology
      Filadelfia, Pennsylvania, United States
  • 2007–2012
    • William Penn University
      Filadelfia, Pennsylvania, United States
  • 2008–2011
    • Temple University
      • Department of Psychology
      Philadelphia, Pennsylvania, United States
    • Drexel University College of Medicine
      • Department of Neurology
      Philadelphia, Pennsylvania, United States
  • 2010
    • King's College London
      • Department of Psychology
      London, ENG, United Kingdom
  • 2006
    • Columbia University
      • Department of Neuroscience
      New York City, NY, United States
  • 2005–2006
    • Stratford University
      Stratford, Connecticut, United States
  • 2004
    • Hospital of the University of Pennsylvania
      • Department of Neurology
      Philadelphia, Pennsylvania, United States
  • 2002
    • Boston University
      • Department of Psychiatry
      Boston, Massachusetts, United States
  • 1996–2002
    • Crozer Chester Medical Center
      Upland, Pennsylvania, United States
  • 1990
    • Albert Einstein Medical Center
      Philadelphia, Pennsylvania, United States