Anthony Y Stringer

Emory University, Atlanta, GA, United States

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Publications (17)44.85 Total impact

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    ABSTRACT: Several recent reviews have suggested that cognitive rehabilitation may hold promise in the treatment of memory deficits experienced by patients with mild cognitive impairment. In contrast to the previous reviews that mainly focused on outcome, the current review examines key methodological challenges that are critical for designing and interpreting research studies and translating results into clinical practice. Using methodological details from 36 studies, we first examine diagnostic variability and how the use of cutoffs may bias samples toward more severely impaired patients. Second, the strengths and limitations of several common rehabilitative techniques are discussed. Half of the reviewed studies used a multi-technique approach that precludes the causal attribution between any specific technique and subsequent improvement. Third, there is a clear need to examine the dose-response relationship since this information was strikingly absent from most studies. Fourth, outcome measures varied widely and frequently depended on neuropsychological tests with little theoretical justification or ecological relevance. Fifth, we discuss how the variability in each of these other four areas complicates efforts to examine training generalization. Overall, future studies should place greater emphasis on ecologically relevant treatment approaches and outcome measures and we propose a hierarchical model that may aid in this pursuit. (JINS, 2014, 19, 1-17).
    Journal of the International Neuropsychological Society 12/2013; · 2.70 Impact Factor
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    ABSTRACT: To evaluate the efficacy of mnemonic strategy training versus a matched-exposure control condition and to examine the relationship between training-related gains, neuropsychological abilities, and medial temporal lobe volumetrics in patients with amnestic mild cognitive impairment (aMCI) and age-matched healthy controls. Twenty-three of 45 screened healthy controls and 29 of 42 screened patients with aMCI were randomized to mnemonic strategy or matched-exposure groups. Groups were run in parallel, with participants blind to the other intervention. All participants completed five sessions within 2 weeks. Memory testing for object-location associations (OLAs) was performed during sessions one and five and at a 1-month follow-up. During Sessions 2-4, participants received either mnemonic strategy training or a matched number of exposures with corrective feedback for a total of 45 OLAs. Structural magnetic resonance imaging was performed in most participants, and medial temporal lobe volumetrics were acquired. Twenty-one healthy controls and 28 patients with aMCI were included in data analysis. Mnemonic strategy training was significantly more beneficial than matched exposure immediately after training, p = .006, partial η2 = .16, and at 1 month, p < .001, partial η2 = .35, regardless of diagnostic group (healthy group or aMCI group). Although patients with aMCI demonstrated gains comparable to the healthy control groups, their overall performance generally remained reduced. Mnemonic strategy-related improvement was correlated positively with baseline memory and executive functioning and negatively with inferior lateral ventricle volume in patients with aMCI; no significant relationships were evident in matched-exposure patients. Mnemonic strategies effectively improve memory for specific content for at least 1 month in patients with aMCI.
    Neuropsychology 03/2012; 26(3):385-99. · 3.58 Impact Factor
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    ABSTRACT: Learning and memory deficits typify patients with mild cognitive impairment (MCI) and are generally attributed to medial temporal lobe dysfunction. Although the hippocampus is perhaps the most commonly studied neuroanatomical structure in these patients, there have been few attempts to identify rehabilitative interventions that facilitate its functioning. Here, we present results from a randomized, controlled, single-blind study in which patients with MCI and healthy elderly controls (HEC) were randomized to either three sessions of mnemonic strategy training (MS) or a matched-exposure control group (XP). All participants underwent pre- and posttraining fMRI scanning as they encoded and retrieved object-location associations. For the current report, fMRI analyses were restricted to the hippocampus, as defined anatomically. Before training, MCI patients showed reduced hippocampal activity during both encoding and retrieval, relative to HEC. Following training, the MCI MS group demonstrated increased activity during both encoding and retrieval. There were significant differences between the MCI MS and MCI XP groups during retrieval, especially within the right hippocampus. Thus, MS facilitated hippocampal functioning in a partially restorative manner. We conclude that cognitive rehabilitation techniques may help mitigate hippocampal dysfunction in MCI patients.
    Hippocampus 02/2012; 22(8):1652-8. · 5.49 Impact Factor
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    ABSTRACT: Posterior reversible encephalopathy syndrome (PRES) is a neurotoxic and neurometabolic state associated with a distinct appearance on computed tomography and magnetic resonance imaging, as well as particular clinical features. While PRES is defined as a reversible condition, instances of irreversible or persisting cytotoxic edema have been reported and appear to be associated with poor outcomes. Studies addressing the post-acute neurocognitive findings in persisting/irreversible PRES are lacking. We report two cases of persisting PRES with associated neurocognitive deficits and functional limitations following acute presentation. Neuroimaging revealed abnormalities within the posterior parietal lobes, along with bilateral involvement of the occipital and frontal lobes. The results from the neuropsychological examination revealed a pattern of impairment generally affecting spatial-perceptual and related functions and aspects of executive function. These cases document instances of irreversible/persisting PRES with associated neurocognitive deficits and functional limitations generally corresponding with the areas implicated on neuroimaging. Studies addressing the post-acute neurocognitive presentation and functional outcomes of PRES are needed.
    The Clinical Neuropsychologist 11/2011; 25(8):1386-402. · 1.68 Impact Factor
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    ABSTRACT: Remembering the location of objects in the environment is both important in everyday life and difficult for patients with amnestic mild cognitive impairment (aMCI), a clinical precursor to Alzheimer's disease. To test the hypothesis that memory impairment for object location in aMCI reflects hippocampal dysfunction, we used an event-related functional magnetic resonance imaging paradigm to compare patients with aMCI and healthy elderly controls (HEC) as they encoded 90 ecologically relevant object-location associations (OLAs). Two additional OLAs, repeated a total of 45 times, served as control stimuli. Memory for these OLAs was assessed following a 1-h delay. The groups were well matched on demographics and brain volumetrics. Behaviorally, HEC remembered significantly more OLAs than did aMCI patients. Activity differences were assessed by contrasting activation for successfully encoded Novel stimuli vs. Repeated stimuli. The HEC demonstrated activity within object-related (ventral visual stream), spatial location-related (dorsal visual stream), and feature binding-related cortical regions (hippocampus and other memory-related regions) as well as in frontal cortex and associated subcortical structures. Activity in most of these regions correlated with memory test performance. Although the aMCI patients demonstrated a similar activation pattern, the HEC showed significantly greater activity within each of these regions. Memory test performance in aMCI patients, in contrast to the HEC, was correlated with activity in regions involved in sensorimotor processing. We conclude that aMCI patients demonstrate widespread cerebral dysfunction, not limited to the hippocampus, and rely on encoding-related mechanisms that differ substantially from healthy individuals.
    Neuropsychologia 04/2011; 49(9):2349-61. · 3.48 Impact Factor
  • Anthony Y Stringer
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    ABSTRACT: The current study looked for a differential response to memory rehabilitation, testing the hypotheses that outcome would vary significantly as a function of patient diagnosis and severity of memory impairment. Unblinded, open-label, pre/post-treatment comparison of memory rehabilitation in patients stratified by diagnosis (brain injury, n = 15; stroke, n = 12; other neurological condition, n = 6) and memory impairment severity. Patients underwent an ecologically-oriented, strategy-based intervention for memory impairment and were evaluated pre- and post-treatment on seven simulations (four with alternate forms, randomized to the pre- or post-test) of everyday declarative or prospective memory tasks. Patients at all levels of severity and in all three diagnostic groups showed equivalent, statistically significant improvement in memory performance. Neither practice effects from repeat test administration nor spontaneous recovery accounted for the improvement in memory performance. The current study provided evidence of improved performance in everyday memory content domains with compensatory-based cognitive rehabilitation. Comparable improvement was seen across diagnostic groups and severity ranges. Additional case series and randomized clinical trials are needed to evaluate further the efficacy of compensation-based approaches to cognitive rehabilitation.
    Brain Injury 01/2011; 25(2):169-78. · 1.51 Impact Factor
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    ABSTRACT: Mild cognitive impairment (MCI) is often a precursor to Alzheimer disease. Little research has examined the efficacy of cognitive rehabilitation in patients with MCI, and the relevant neural mechanisms have not been explored. The authors previously showed the behavioral efficacy of cognitive rehabilitation using mnemonic strategies for face-name associations in patients with MCI. Here, the authors used functional magnetic resonance imaging (fMRI) to test whether there were training-specific changes in activation and connectivity within memory-related areas. A total of 6 patients with amnestic, multidomain MCI underwent pretraining and posttraining fMRI scans, during which they encoded 90 novel face-name pairs and completed a 4-choice recognition memory test immediately after scanning. Patients were taught mnemonic strategies for half the face-name pairs during 3 intervening training sessions. Training-specific effects comprised significantly increased activation within a widespread cerebral cortical network involving medial frontal, parietal, and occipital regions; the left frontal operculum and angular gyrus; and regions in the left lateral temporal cortex. Increased activation common to trained and untrained stimuli was found in a separate network involving inferior frontal, lateral parietal, and occipital cortical regions. Effective connectivity analysis using multivariate, correlation-purged Granger causality analysis revealed generally increased connectivity after training, particularly involving the middle temporal gyrus and foci in the occipital cortex and the precuneus. The authors' findings suggest that the effectiveness of explicit-memory training in patients with MCI is associated with training-specific increases in activation and connectivity in a distributed neural system that includes areas involved in explicit memory.
    Neurorehabilitation and neural repair 10/2010; 25(3):210-22. · 4.28 Impact Factor
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    ABSTRACT: Because many visuospatial memory tests do not reliably detect right medial temporal lobe (MTL) dysfunction, we developed a novel object recognition test using complex three-dimensional stimuli. To influence encoding strategy, half the stimuli were multicolored (color towers) and accompanied by verbally based instructions, and half were gray (gray towers) and accompanied by visuospatially based instructions. In Experiment 1, healthy subjects completed the test while performing verbal or visuospatial interference tasks or without interference. In Experiment 2, patients with unilateral amygdalohippocampectomies for intractable epilepsy completed the test without interference. Results suggest that color tower recognition was partially dependent on verbal processing and sensitive to MTL lesions in general. Recognition of gray towers was reliant on visuospatial processing, and the decay in accuracy after a delay was sensitive and specific to right MTL lesions. These findings suggest that test stimuli such as three-dimensional objects can be useful in assessing right MTL dysfunction.
    Epilepsy & Behavior 05/2010; 18(1-2):54-60. · 1.84 Impact Factor
  • NeuroImage 01/2009; 47. · 6.25 Impact Factor
  • Alzheimers & Dementia - ALZHEIMERS DEMENT. 01/2009; 5(4).
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    ABSTRACT: Relatively few studies have examined the use of cognitive rehabilitation in patients with mild cognitive impairment (MCI), largely due to the assumption that training will not improve functioning in patients with progressive conditions. Face-name association, an ecologically valid task, is both dependent on the explicit memory system and difficult for MCI patients. During three hour-long sessions, eight patients diagnosed with MCI were trained in the use of explicit memory strategies with 45 face-name pairs. For each pair, they were taught to visually identify a facial feature, link a phonological cue to that feature, and recall the associated name. There was significant improvement in recognition accuracy, along with faster reaction times, for trained face-name pairs. Improved accuracy persisted when tested one month after training. Significant, but less, improvement was also found on untrained stimuli, raising the possibility of generalization of training strategies. Preliminary results suggest strategy-based cognitive rehabilitation may be beneficial in patients with MCI, though these results must be replicated with a control group to rule out practice effects.
    Journal of the International Neuropsychological Society 10/2008; 14(5):883-9. · 2.70 Impact Factor
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    ABSTRACT: To examine the relationship between gender and cognitive recovery 1 year following traumatic brain injury (TBI). Patients with blunt TBI were identified from the TBI Model Systems of Care National Database, multi-centre cohort study. The included patients (n = 325) were 16-45 years at injury, admitted to an acute care facility within 24 hours, received inpatient rehabilitation, had documented admission Glasgow Coma Scale (GCS) scores, completed neuropsychological follow-up 1 year post-injury and did not report pre-morbid learning problems. Multivariate analyses of variance examined the unadjusted association between gender and six cognitive domains examining attention/working memory, verbal memory, language, visual analytic skills, problem-solving and motor functioning. Analyses of covariance models were constructed to determine if confounding factors biased the observed associations. Females performed significantly better than males on tests of attention/working memory and language. Males outperformed females in visual analytic skills. Gender remained significantly associated with performance in these areas when controlling for confounding variables. These results suggest a better cognitive recovery of females than males following TBI. However, future studies need to include non-TBI patients to control for possible pre-injury gender-related differences, as well as to conduct extended follow-ups to determine the stability of the observed differences.
    Brain Injury 10/2007; 21(10):1023-30. · 1.51 Impact Factor
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    ABSTRACT: (1) To examine survivors with traumatic brain injury (TBI) for symptoms of avoidance and intrusion, two dimensions of post-traumatic stress (PTS) at 6 and 12 months post-injury. (2) To identify risk factors associated with these symptoms. Prospective follow-up study. Georgia and North Carolina Model Brain Injury Systems participants (n = 198) with mild (19%), moderate (21%) and severe (60%) TBI were interviewed by telephone at 6 and 12 months post-injury. The Impact of Event Scale (IES) was used to identify intrusion and avoidance symptoms. Symptoms consistent with severe PTS increased from 11% at 6 months to 16% 12 months post-injury (p < 0.003). African-Americans (p < 0.01) and women (p < 0.05) reported greater symptomatology at 12 months compared to their counterparts. TBI severity and memory of the event were not associated with PTS-like symptoms. Symptoms increased over time when examined by race, injury intent, gender and age (p < 0.05). Regardless of severity, survivors with TBI are at risk for developing symptoms consistent with PTS. Amnesia for the injury event was not protective against developing these symptoms. African-Americans appear to be at greatest risk.
    Brain Injury 07/2006; 20(7):733-42. · 1.51 Impact Factor
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    ABSTRACT: To examine the relationship between cortical lesion location and brain injury outcome. It was hypothesized that focal frontal lesions after traumatic brain injury (TBI) would result in decreased executive and memory functioning and poor community participation outcome. Three quasi-experimental, prospective studies employed a total of 643 patients with focal frontal, fronto-temporal, non-frontal or no lesions in CT scans. CT scan analysis, neuropsychological assessment, the Neurobehavioural Functioning Inventory (NFI), the Community Integration Questionnaire (CIQ). In study 1, frontal and fronto-temporal groups performed worse in executive functioning and better in constructional ability. Study 2 found no differences in neuropsychological and community re-integration measures at 1-year follow-up. Study 3 found comparable neuropsychological test score improvement across groups over 1 year. Results are consistent with previous findings and document the potential for test score improvement with rehabilitation and suggest that lesion location needs to be considered when individual rehabilitation plans are being implemented in the post-acute stage of TBI.
    Brain Injury 05/2005; 19(4):239-56. · 1.51 Impact Factor
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    ABSTRACT: To validate a model that examines the contribution of premorbid variables, injury severity, and functional and cognitive status to outcome 1 year after traumatic brain injury (TBI). Cross-validation study using a larger, national, prospective, longitudinal sample. Acute inpatient rehabilitation hospitals at Traumatic Brain Injury Model Systems centers. Two sample populations followed through acute rehabilitation to 1 year after TBI. The original sample included 107 patients, and the cross-validation sample included 294 patients. Participants were predominantly young men who had experienced moderate to severe TBI in motor vehicle crashes. Acute medical and rehabilitation care. Disability Rating Scale, Community Integration Questionnaire, and return to employment. Structural equation modeling was used to compare the fit of the data to a path analysis developed through clinical use and previous research. Both samples provided adequate goodness of fit, supporting the model's validity. Injury severity affected cognitive and functional status, and cognitive and functional status significantly influenced 1-year outcome. Premorbid factors and injury severity did not directly influence outcome. Both samples supported the proposed model, which was cross-validated. Injury severity indirectly influences outcome through its effects on cognitive and functional status. Although treatment to decrease injury severity is obviously important, concentrated rehabilitation interventions aimed at improving patients' cognitive and functional status may have a more significant impact on 1-year outcome and should be the focus of future research.
    Archives of Physical Medicine and Rehabilitation 01/2004; 84(12):1803-7. · 2.36 Impact Factor
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    ABSTRACT: To describe the medical and rehabilitation service use of model systems by brain injured participants 1 to 3 months postdischarge from inpatient rehabilitation. Prospective follow-up study. Georgia Model Brain Injury System (GAMBIS). Seventy-three GAMBIS subjects consenting to participate in the utilization substudy. Receipt of services and intensity of service use. Chi-square analysis of receipt of services by severity of injury. The likelihood of service use did not vary with severity of injury. Data suggest that intensity of service use was a function of injury severity. Subjects with mild and moderate injuries were as likely to use a range of medical and rehabilitation services during the 3-month postdischarge period as those with severe injuries. Traditional rehabilitation services, such as physical therapy, were far more likely to be used, than nontraditional services, such as psychological counseling, in spite of the high level of cognitive and social disability associated with traumatic brain injury.
    Journal of Head Trauma Rehabilitation 01/2004; 19(3):217-25. · 4.44 Impact Factor
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    ABSTRACT: Bush BA, Novack TA, Malec JF, Stringer AY, Millis SR, Madan A. Validation of a model for evaluating outcome after traumatic brain injury. Arch Phys Med Rehabil 2003;84:1803–7.
    Archives of Physical Medicine and Rehabilitation - ARCH PHYS MED REHABIL. 01/2003; 84(12):1803-1807.