Nick M. Wisdom

The effects of apolipoprotein E on non-impaired cognitive functioning: A meta-analysis

Nearly twice as many participants are represented in the current literature than were available at the time of the last major meta-analytic neurocognitive examination of apolipoprotein E (ApoE) epsilon allele combinations [Small, B.J., Rosnick, C.B., Fratiglioni, L., Backman, L., 2004. Apolipoprotein E and cognitive performance: a meta-analysis. Psychol. Aging 19, 592-600]. The meta-analysis in the current study sought to specifically examine (1) small effects and (2) possible moderating variables associated with ApoE allele combinations that may have been undiscoverable in previous examinations of smaller data sets. A total of 77 studies, representing 40,942 cognitively healthy adults were identified for inclusion in the current meta-analysis (random effects design). Results were congruent with the previous meta-analytic findings indicating that carriers of ApoE allele 4 (ɛ4) perform significantly worse on measures of episodic memory, executive functioning, and overall global cognitive ability. In addition, the current analysis revealed a small effect suggesting that ApoE allele 4 adversely impacts perceptual speed. In contrast to earlier studies, the results also indicate that increases in age result in significantly larger differences between ApoE ɛ4 carriers and ApoE non-ɛ4 carriers on measures of episodic memory and global cognitive ability. ApoE ɛ4 exerts broad, but specific, adverse small effects on a range of neurocognitive functions in cognitively healthy adults.

PTSD and Cognitive Functioning: Importance of Including Performance Validity Testing

Many studies have observed an association between post-traumatic stress disorder (PTSD) and cognitive deficits across several domains including memory, attention, and executive functioning. The inclusion of response bias measures in these studies, however, remains largely unaddressed. The purpose of this study was to identify possible cognitive impairments correlated with PTSD in returning OEF/OIF/OND veterans after excluding individuals failing a well-validated performance validity test. Participants included 126 men and 8 women with a history of mild traumatic brain injury (TBI) referred for a comprehensive neuropsychological evaluation as part of a consortium of five Veterans Affairs hospitals. The PTSD CheckList (PCL) and Word Memory Test (WMT) were used to establish symptoms of PTSD and invalid performance, respectively. Groups were categorized as follows: Control (PCL < 50, pass WMT), PTSD-pass (PCL ≥ 50, pass WMT), and PTSD-fail (PCL ≥ 50, fail WMT). As hypothesized, failure on the WMT was associated with significantly poorer performance on almost all cognitive tests administered; however, no significant differences were detected between individuals with and without PTSD symptoms after separating out veterans failing the WMT. These findings highlight the importance of assessing respondent validity in future research examining cognitive functioning in psychiatric illness and warrant further consideration of prior studies reporting PTSD-associated cognitive deficits.

Diagnostic Utility of the Structured Inventory of Malingered Symptomatology to Detect Malingering in a Forensic Sample

The Structured Inventory of Malingered Symptomatology (SIMS) is a 75-item, self-report measure to be used with individuals at least 18 years of age, which may be utilized to assess potential malingering of psychosis, neurologic impairment, amnesia, low intelligence, or affective disorder. However, no studies in the literature have examined the diagnostic validity of this instrument in a known-groups design involving medicolegal referrals diagnosed as malingering using the criteria outlined by Slick and colleagues [Slick, D. J., Sherman, E. M. S., & Iverson, G. L. (1999). Diagnostic criteria for malingered neurocognitive dysfunction: Proposed standards for clinical practice and research. The Clinical Neuropsychologist, 13, 545-561]. The current known-groups, archival study was designed to examine the effectiveness of the SIMS at identifying malingering in patients involved in personal injury lawsuits or disability claims. Findings indicate that a higher cut score on the SIMS for identification of malingering may be appropriate for use with this population. Limitations, clinical implications, and suggestions for further research are discussed.

The use of all three Test of Memory Malingering trials in establishing the level of effort.

Assessment of the effort level is an essential step in establishing the internal validity of any neuropsychological evaluation. The use of response bias measures as part of a core battery, however, is less common outside of forensic evaluations. The amount of time needed to administer many of these tests is often cited as a likely explanation for their exclusion from routine neuropsychological evaluations. This study examined all three trials of the Test of Memory Malingering (TOMM) in a large sample (n = 213) of inpatients on an epilepsy monitoring unit with the goal of establishing cut scores for early termination. TOMM Trial 1 demonstrated impressive diagnostic accuracy for determining both adequate and suboptimal levels of effort; various cut scores and classification statistics are presented. The optional Retention trial from the TOMM also increased the hit rate 16% in the detection of poor effort. Clinical implications, limitations, and directions for further research are discussed.

A retrospective review of digit span-related effort indicators in probable Alzheimer's disease patients.

There has been extensive research on the use of both stand-alone and embedded measures of effort in neuropsychological testing; however, relatively few studies have reported on their utility in the context of dementia. Previous studies that have examined the specificity of traditionally used cut-scores on embedded measures of effort with dementia samples have largely found high rates of false positive errors. The present study examined the specificity of several Digit Span derived embedded measures of effort in a large clinical sample of patients with probable Alzheimers disease stratified by level of dementia severity. Of the measures that were examined, only the Vocabulary – Digit Span score demonstrated promising specificity through the moderate level of dementia severity. All of the remaining indices, including Reliable Digit Span, Digit Span Age-Corrected Scaled Score, and Longest Digits Forward (1 & 2 Trials), yielded unacceptable rates of false positive errors as dementia severity increased. The implications for these findings are discussed, including the limitations of importing methods of assessing effort from one sample to another.

Diagnostic utility of the Structured Inventory of Malingered Symptomatology for identifying psychogenic non-epileptic events

The Structured Interview of Malingered Symptomatology (SIMS) is a self-report instrument that asks patients whether they experience atypical or implausible symptoms. The instrument has not been evaluated in an epilepsy population, and the potential for it to accurately distinguish between patients with psychogenic non-epileptic events (PNEE) and epileptic event groups has not been established. The SIMS was administered to patients in long-term video-EEG monitoring of these patients, 91 with PNEE and 29 with epilepsy were included in this study. Structured Interview of Malingered Symptomatology total scores as well as neurological and affective subscales were found to be predictors of group membership. Sensitivity and specificity across several different base rates of PNEE as well as maximum level likelihood ratios are presented. The findings not only demonstrate the utility of marked score elevations in differentiating PNEE from epilepsy but also point to considerable caution in interpreting mild elevations. Implications for the utility of this instrument in epilepsy evaluations are discussed.

Intact vs. impaired ictal sensorium: Does it affect outcome of psychogenic nonepileptic events following disclosure of diagnosis?

It remains uncertain whether particular ictal manifestations of psychogenic nonepileptic events (PNEE) can reflect distinctive psychological processes or prognostic outcomes. We hypothesize that the integrity of ictal sensorium may affect the clinical outcome of PNEE following disclosure of diagnosis. We prospectively studied 47 veterans who were diagnosed with video-EEG-confirmed PNEE, presented with the diagnosis utilizing a standardized communication strategy, and followed for their clinical progress. When compared to patients with intact ictal sensorium, significantly smaller proportion of patients with impaired ictal sensorium endorsed improvement of either PNEE frequency or intensity across both the initial 1- to 3-month (p=0.005) and ensuing 6- to 9-month (p=0.01) follow-ups. However, improvement among patients with impaired ictal sensorium was more significantly associated with their level of understanding for the PNEE diagnosis across both the initial (rho=0.41, p=0.017) and ensuing (rho=0.43, p=0.015) follow-ups. Our study presents preliminary evidence underscoring the potential clinical significance of ictal sensorial integrity when evaluating patients with PNEE.