Aaron Nelson

Self-recognition and the right hemisphere.

Although monkeys can perceive complex stimuli such as faces, only the higher apes are capable of recognizing their own face in a mirror. Here we show that in humans the right hemisphere of the brain seems to be preferentially involved in self-face recognition. Our findings indicate that neural substrates of the right hemisphere may selectively participate in processes linked to self-awareness.

Bedside Cognitive Screening Instruments: A Critical Assessment

Bedside cognitive screening instruments are used increasingly in clinical and research settings to detect cognitive impairment and to quantify its severity. The authors review the five most frequently cited bedside screening tests that use an interview format and require brief administration times: the Mini-Mental State Examination, the Cognitive Capacity Screening Examination, Mattis Dementia Rating Scale, Kahns Mental Status Questionnaire, and the Short Portable Mental Status Questionnaire. The tests all have adequate inter-rater reliability, and adequate test-retest reliability has been established for three of the tests. All of the tests show close correspondence with clinical diagnoses of delirium and dementia and are useful for the diagnosis and quantification of these syndromes. However, there is currently no evidence that the tests increase the level of diagnostic accuracy achieved through clinical examination alone. All of the tests have substantial false-negative rates, with false-negative errors frequent among patients with focal lesions, particularly of the right hemisphere. False-positive errors may be more common among patients with less education and lower socioeconomic status. The tests reviewed do not detect many types of cognitive deficit that may bear critically on differential diagnosis and case management. Suggestions are given for further research on the current measures and for the development of new screening tests that would meet a broader range of clinical purposes.

Mild cognitive impairment: a neuropsychological perspective.

Mild cognitive impairment (MCI) is a clinical diagnosis in which deficits in cognitive function are evident but not of sufficient severity to warrant a diagnosis of dementia. For the majority of patients, MCI represents a transitional state between normal aging and mild dementia, usually Alzheimers disease. Multiple subtypes of MCI are now recognized. In addition to presentations featuring memory impairment, symptoms in other cognitive domains (eg, executive function, language, visuospatial) have been identified. Neuropsychological testing can be extremely useful in making the MCI diagnosis and tracking the evolution of cognitive symptoms over time. A comprehensive test battery includes measures of baseline intellectual ability, attention, executive function, memory, language, visuospatial skills, and mood. Informant-based measures of neuropsychiatric symptoms, behaviors, and competency in instrumental activity are also included. Careful assessment can identify subtle deficits that may otherwise elude detection, particularly in individuals of superior baseline intellectual ability. As we move closer to disease-modifying therapy for Alzheimers disease, early identification becomes critical for identifying patients who have an opportunity to benefit from treatment.

Threshold-independent functional MRI determination of language dominance: A validation study against clinical gold standards

Functional MRI (fMRI) is often used for presurgical language lateralization. In the most common approach, a laterality index (LI) is calculated on the basis of suprathreshold voxels. However, strong dependencies between LI and threshold can diminish the effectiveness of this technique; in this study we investigated an original methodology that is independent of threshold. We compared this threshold-independent method against the common threshold-dependent method in 14 patients with epilepsy who underwent Wada testing. In addition, clinical results from electrocortical language mapping and postoperative language findings were used to assess the validity of the fMRI lateralization method. The threshold-dependent methodology yielded ambiguous or incongruent lateralization outcomes in 4 of 14 patients in the inferior frontal gyrus (IFG) and in 6 of 14 patients in the supramarginal gyrus (SMG). Conversely, the threshold-independent method yielded unambiguous lateralization in all the patients tested, and demonstrated lateralization outcomes incongruent with clinical standards in 2 of 14 patients in IFG and in 1 of 14 patients in SMG. This validation study demonstrates that the threshold-dependent LI calculation is prone to significant within-patient variability that could render results unreliable; the threshold-independent method can generate distinct LIs that are more concordant with gold standard clinical findings.

Clinical characteristics of psychogenic nonepileptic seizure status in the long-term monitoring unit

Patients with psychogenic nonepileptic seizures (PNES) mimicking status epilepticus (PNES-status) are at risk of iatrogenic complications. Our aim was to assess whether the population of patients with PNES who develop PNES-status are distinguishable. Retrospectively, we identified patients with PNES-status and compared them with patients with PNES without status and with patients with electroclinical status epilepticus (SE). Of 49 patients with PNES, 9 had PNES-status (18.2%) and 40 had PNES only. Compared with patients with PNES, subjects with PNES-status had taken fewer than three antiepileptic medications (P=0.016), had more than one event per week (P=0.026), were more likely to be admitted emergently to the monitoring unit (P=0.007), had shorter long-term monitoring (LTM) stays (P=0.003), and tended to be diagnosed sooner after initial presentation (P=0.058). Use of fewer than three antiepileptic drugs and emergent admission were independent predictors of PNES-status classification on logistic regression. Of 154 patients with epilepsy, 8 had SE during LTM (5.2%), significantly fewer than the proportion with PNES-status relative to PNES (P=0.008); the only clinical variable distinguishing these two groups was a baseline lower seizure frequency among the patients with epileptic seizures (P=0.045). Our results suggest that patients with PNES-status have features that differentiate them from patients with PNES without status and, to a lesser extent, from patients with epileptic seizures.

The role of sleep in forgetting in temporal lobe epilepsy: A pilot study

The purpose of this study was to examine how sleep impacts memory function in temporal lobe epilepsy (TLE). Patients with TLE (n=7) and control subjects (n=9) underwent training and overnight testing on (1) a motor sequence task known to undergo sleep-dependent enhancement in healthy subjects, and (2) the selective reminding test, a verbal memory task on which patients with TLE have shown impaired performance 24 hours after training. Sleep data were collected by polysomnography. Results indicate that patients with TLE display greater forgetting on the selective reminding test compared with controls over 12 hours of daytime wakefulness, but not over a similar period including a night of sleep. Slow wave sleep is correlated with overnight performance change on the selective reminding test. Patients with TLE show no deficit in sleep-dependent motor sequence task improvement. The findings provide potential insight into the pattern and pathophysiology of forgetting in TLE.

Comparison of outcomes of video/EEG monitoring between patients with epileptic seizures and those with psychogenic nonepileptic seizures

We followed 103 patients for 6-16 months after discharge from elective long-term video/EEG monitoring to compare clinical outcomes and quality of life between patients diagnosed with epileptic (ES) and those diagnosed with psychogenic nonepileptic (PNES) seizures. Outcome measures determined at telephone or mail follow-up included seizure frequency, antiepileptic drug use, and self-reported quality of life using the Quality of Life in Epilepsy inventory. Of the 62 responders, 41 were diagnosed with ES and 11 with PNES, using strictly applied criteria. Those with ES reported significant improvement in Seizure Worry (P=0.003), Medication Side Effects (P<0.001), and Social Function (P<0.001). In addition, both groups showed a decrease in seizure frequency. Furthermore, both groups showed a significant decrease in antiepileptic drug use at follow-up, with a greater, and sustained, decrease for the PNES group. Approximately half the patients in each group reported an improvement in overall condition.

Official Position of the American Academy of Clinical Neuropsychology (AACN): Guidelines for Practicum Training in Clinical Neuropsychology

Practical experience is central to the education and training of neuropsychologists, beginning in graduate school and extending through postdoctoral fellowship. However, historically, little attention has been given to the structure and requirements of practicum training in clinical neuropsychology. A working group of senior-level neuropsychologists, as well as a current postdoctoral fellow, all from a diverse range of settings (The AACN Practicum Guidelines Workgroup), was formed to propose guidelines for practicum training in clinical neuropsychology. The Workgroup reviewed relevant literature and sought input from professional organizations involved in education and training in neuropsychology. The proposed guidelines provide a definition of practicum training in clinical neuropsychology, detail entry and exit criteria across competencies relevant to practicum training in clinical neuropsychology, and discuss the relationship between doctoral training programs and practicum training sites. The proposed guidelines also provide a methodology for competency-based evaluation of clinical neuropsychology practicum trainees and outline characteristics and features that are integral to an effective training environment. Although the guidelines discussed below may not be implemented in their entirety across all clinical neuropsychology practicum training sites, they are consistent with the latest developments in competency-based education.

Response to Bodin and Grote regarding postdoctoral recruitment in clinical neuropsychology.

Abstract Bodin and Grote convey their opinion that the field of clinical neuropsychology would be best served by a match system for recruitment into postdoctoral training. We critically review their arguments and offer an alternative point of view. Our view considers the current state of the match system in neuropsychology, incorporates comparisons with other disciplines that rely on a match system, and addresses the role of postdoctoral training and the specialization that takes shape at this level. We make recommendations aimed at promoting greater unity among postdoctoral training programs with the goal of focusing leadership efforts on advancing our shared mission of providing the highest quality training in clinical neuropsychology.

Cognitive, Emotional, and Behavioral Inflexibility and Perseveration in Neuropsychiatric Illness

Cognitive and behavioral flexibility is a core adaptive function of the executive control system in the human brain. Executive functions include a set of processes that allow for context-appropriate volitional control in “nonroutine situations.” Goal-directed behavior requires not only an ability to represent a goal and then generate a plausible sequence of actions that must be accomplished to achieve it but also an ability to prioritize goals (represent the relative value of various goals at a given time), initiate a goal-directed process, and maintain goal pursuit in the face of unexpected environmental factors that might otherwise command attention. Too much environmental dependency will result in distractibility, a tendency for tasks to be interrupted, and, ultimately, an inability to complete a complex task sequence aimed toward a particular goal. This can manifest clinically as impulsivity, where the individual quickly shifts tasks in response to a novel stimulus, leaving the prior task sequence incomplete. However, one must also be able to discontinue an activity, switching to a different task when appropriate. An excessively rigid adherence to a predetermined task sequence or a previously valued goal prevents an individual from appropriately responding to changing environmental contingencies. We examine a variety of forms of cognitive, emotional, and behavioral perseveration in neuropsychiatric disease, and explore the various mechanisms believed to account for these phenomena. In many neuropsychiatric illnesses, impairments of flexibility in one form or another account for a significant restriction in the range of reactions, feelings, and self-generated behaviors an individual may exhibit, leading to a breakdown in social and occupational functioning, and in many cases, significant suffering. Perseveration, in its broadest conceptualization, can occur at a variety of levels of organization from simple motor behaviors (i.e., tics), verbal utterances, complex cognitions (i.e., obsessions in obsessive compulsive disorder, perseverative rumination in mood and anxiety disorders, fixed delusions in psychosis), complex behaviors (i.e., compulsions in obsessive compulsive disorder and addiction), and perseveration of affect in mood and anxiety disorders.