Performance validity testing in a clinical sample of adults with sickle cell disease

Objective: Neuropsychologists utilize performance validity tests (PVTs) as objective means for drawing inferences about performance validity. The Test of Memory Malingering (TOMM) is a well-validated, stand-alone PVT and the Reliable Digit Span (RDS) and Reliable Digit Span-Revised (RDS-R) from the Digit Span subtest of the WAIS-IV are commonly employed, embedded PVTs. While research has demonstrated the utility of these PVTs with various clinical samples, no research has investigated their use in adults with sickle cell disease (SCD), a condition associated with multiple neurological, physical, and psychiatric symptoms. Thus, the purpose of this study was to explore PVT performance in adults with SCD. Method: Fifty-four adults with SCD (M_age = 40.61, SD = 12.35) were consecutively referred by their hematologist for a routine clinical outpatient neuropsychological evaluation. During the evaluation, participants were administered the TOMM (Trials 1 and 2), neuropsychological measures including the WAIS-IV Digit Span subtest, and mood and behavioral questionnaires. Results: The average score on the TOMM was 47.70 (SD = 3.47, range = 34–50) for Trial 1 and 49.69 (SD = 1.66, range = 38–50) for Trial 2. Only one participant failed Trial 2 of the TOMM, yielding a 98.1% pass rate for the sample. Pass rates at various RDS and RDS-R values were calculated with TOMM Trial 2 performance as an external criterion. Conclusions: Results support the use of the TOMM as a measure of performance validity for individuals with SCD, while RDS and RDS-R should be interpreted with caution in this population.     

Test of Memory Malingering (TOMM) Scores are not Affected by Chronic Pain or Depression in Patients with Fibromyalgia

Neuropsychologists routinely give effort tests, such as the Test of Memory Malingering (TOMM). When a person fails one of these tests, the clinician must try to determine whether the poor performance was due to suboptimal effort or to chronic pain, depression, or other problems. Participants were 54 community-dwelling patients who met American College of Rheumatology criteria for fibromyalgia (FM). In addition to the TOMM, they completed the Beck Depression Inventory–Second Edition, Multidimensional Pain Inventory–Version 1, Oswestry Disability Index–2.0, British Columbia Cognitive Complaints Inventory, and the Fibromyalgia Impact Questionnaire. The majority endorsed at least mild levels of depressive symptoms (72%), and 22% endorsed “severe” levels of depression. The average scores on the TOMM were 48.8 (SD = 1.9, range = 40–50) for Trial 1, 49.8 (SD = 0.5, range = 48–50) for Trial 2, and 49.6 (SD = 0.9, range = 45–50) for Retention. Despite relatively high levels of self-reported depression, chronic pain, and disability, not a single patient failed the TOMM. In this study, the TOMM was not affected by chronic pain, depression, or both.     

The use of the Rey 15-Item Test and recognition trial to evaluate noncredible effort after pediatric mild traumatic brain injury

The Rey 15-Item Test (FIT) is a performance validity test commonly used in adult neuropsychological assessment. FIT classification statistics across studies have been variable, so a recognition trial was created to enhance the measure (Boone, K. B., Salazar, X., Lu, P., Warner-Chacon, K., & Razani, J. (2002). The Rey 15-Item recognition trial: A technique to enhance sensitivity of the Rey 15-Item Memorization Test. Journal of Clinical and Experimental Neuropsychology, 24(5), 561–573.). The current study assessed the utility of the FIT and recognition trial in a pediatric mild traumatic brain injury sample (N = 319, M = 14.57 years). All participants were administered the FIT and recognition trial as part of an abbreviated clinical neuropsychological evaluation. Failure on the Medical Symptom Validity Test was used as the criterion for noncredible effort. Fifteen percent of the sample met the criterion. The traditional adult cutoff score of <9 on the FIT recall trial yielded excellent specificity (98%), but very poor sensitivity (12%). When the recognition trial was utilized, a total score of <26 resulted in the best combined cutoff score (sensitivity = 55%, specificity = 91%). Results indicate that the FIT with recognition trial may be useful in the assessment of noncredible effort with children and adolescents, at least among relatively high-functioning populations.     

The relationship between alexithymia and salivary cortisol levels in somatoform disorders

The purpose of this study was to investigate cortisol levels as a function of the hypothalamic–pituitary–adrenal axis (HPA) in relation to alexithymia in patients with somatoform disorders (SFD). Diurnal salivary cortisol was sampled in 32 patients with SFD who also underwent a psychiatric examination and filled in questionnaires (Toronto Alexithymia Scale, TAS scale; Screening for Somatoform Symptoms, SOMS scale; Hamilton Depression Scale, HAMD). The mean TAS total score in the sample was 55.6±9.6, 32% of patients being classified as alexithymic on the basis of their TAS scores. Depression scores were moderate (HAMD=13.2, Beck Depression Inventory, BDI=16.5). The patients’ alexithymia scores (TAS scale “Difficulty identifying feelings”) correlated significantly positively with their somatization scale scores (Symptom Checklist-90 Revised, SCL-90-R); r=0.3438 (P<0.05) and their scores on the Global Severity Index (GSI) on the SCL-90-R; r=0.781 (P<0.01). Regression analysis was performed with cortisol variables as the dependent variables. Cortisol levels [measured by the area under the curve–ground (AUC-G), area under the curve–increase (AUC-I) and morning cortisol (MCS)] were best predicted in a multiple linear regression model by lower depressive scores (HAMD) and more psychopathological symptoms (SCL-90-R). No significant correlations were found between the patients’ alexithymia scores (TAS) and cortisol levels. The healthy control group (n=25) demonstrated significantly higher cortisol levels than did the patients with SFD; in both tests P<0.001 for AUC-G and AUC-I. However, the two groups did not differ in terms of their mean morning cortisol levels (P>0.05). The results suggest that pre-existing hypocortisolism might possibly be associated with SFD.     

Temporal Stability of the Dutch Version of the Wechsler Memory Scale—Fourth Edition (WMS-IV-NL)

Objective: The Wechsler Memory Scale—Fourth Edition (WMS-IV) is one of the most widely used memory batteries. We examined the test–retest reliability, practice effects, and standardized regression-based (SRB) change norms for the Dutch version of the WMS-IV (WMS-IV-NL) after both short and long retest intervals. Method: The WMS-IV-NL was administered twice after either a short (M = 8.48 weeks, SD = 3.40 weeks, range = 3–16) or a long (M = 17.87 months, SD = 3.48, range = 12–24) retest interval in a sample of 234 healthy participants (M = 59.55 years, range = 16–90; 118 completed the Adult Battery; and 116 completed the Older Adult Battery). Results: The test–retest reliability estimates varied across indexes. They were adequate to good after a short retest interval (ranging from .74 to .86), with the exception of the Visual Working Memory Index (r = .59), yet generally lower after a long retest interval (ranging from .56 to .77). Practice effects were only observed after a short retest interval (overall group mean gains up to 11 points), whereas no significant change in performance was found after a long retest interval. Furthermore, practice effect-adjusted SRB change norms were calculated for all WMS-IV-NL index scores. Conclusions: Overall, this study shows that the test–retest reliability of the WMS-IV-NL varied across indexes. Practice effects were observed after a short retest interval, but no evidence was found for practice effects after a long retest interval from one to two years. Finally, the SRB change norms were provided for the WMS-IV-NL.     

Effects of Short-Term Dynamic Psychotherapy for Neurotic,Somatoform, and Personality Disorders: a Prospective 1-Year Follow-Up Study

Time-limited psychodynamic therapies in an outpatient setting are offered for a broad spectrum of psychogenic disorders. Chiefly, meta-analyses have proved their effectiveness where neurotic disorders have been concerned. The Cyclic Maladaptive Pattern/Structural Analysis of Social Behavior (CMP/SASB) model (Tress et al., 1996) of short-term dynamic psychotherapy (STDP) in this study was applied to patients with somatoform and personality disorders. Using a naturalistic design, 41 therapists treated 75 patients with personality (n = 24), somatoform (n = 24), and neurotic (n = 27) disorders. Relevant research instruments were Beeinträchtigungsschwere Score (BSS; an impairment score), Global Assessment of Functioning Scale (GAF), CMP, Symptom Checklist (SCL-90-R), and Intrex Introject Questionnaire based on the SASB. The treatments lasted for 25 sessions, and follow-up examinations were performed after 6 months and 1, 2, and 5 years. Effect sizes for the entire sample by BSS and GAF are reported. Somatoform patients benefited the most, but those with personality disorders also profited. Effect sizes of self-ratings (SCL-90-R and Intrex) were not as high. Thus, the CMP/SASB model of STDP is suited not only for neuroses but is especially appropriate for somatoform disorders as well.     

The 15-item version of the Boston Naming Test as an index of English proficiency

Objective: The present study was designed to examine the potential of the Boston Naming Test – Short Form (BNT-15) to provide an objective estimate of English proficiency. A secondary goal was to examine the effect of limited English proficiency (LEP) on neuropsychological test performance.Method: A brief battery of neuropsychological tests was administered to 79 bilingual participants (40.5% male, M_Age = 26.9, M_Education = 14.2). The majority (n = 56) were English dominant (EN), and the rest were Arabic dominant (AR). The BNT-15 was further reduced to 10 items that best discriminated between EN and AR (BNT-10). Participants were divided into low, intermediate, and high English proficiency subsamples based on BNT-10 scores (≤6, 7–8, and ≥9). Performance across groups was compared on neuropsychological tests with high and low verbal mediation.Results: The BNT-15 and BNT-10 respectively correctly identified 89 and 90% of EN and AR participants. Level of English proficiency had a large effect (partial η² = .12–.34; Cohen’s d = .67–1.59) on tests with high verbal mediation (animal fluency, sentence comprehension, word reading), but no effect on tests with low verbal mediation (auditory consonant trigrams, clock drawing, digit-symbol substitution).Conclusions: The BNT-15 and BNT-10 can function as indices of English proficiency and predict the deleterious effect of LEP on neuropsychological tests with high verbal mediation. Interpreting low scores on such measures as evidence of impairment in examinees with LEP would likely overestimate deficits.     

Isolation and characterization of 113 polymorphic microsatellite loci for the Tibetan frog (Nanorana parkeri) using next generation sequencing

We developed and characterized 113 polymorphic microsatellites in the Tibetan frog (Nanorana parkeri) using 454 GS-FLX next generation sequencing technology. These loci were tested in 46 individuals from two N. parkeri populations from the Tibetan plateau. The average number of alleles per locus was 8.09 (range = 2–20). The average observed heterozygosities (H _O) per locus in the two populations were 0.58 (range = 0.04–1) and 0.29 (range = 0–0.87), respectively. These microsatellites will be useful for population and conservation genetics studies of N. parkeri and other closely related species.     

Prevalence of psychological symptoms in contemporary Chinese rural-to-urban migrant workers: an exploratory meta-analysis of observational studies using the SCL-90-R

Purpose

(1) To estimate the pooled prevalence of psychological symptoms in Chinese migrant workers (CMWs), as measured using the Symptom Checklist-90-R (SCL-90-R) in observational studies conducted in China, and (2) to explore the potential variables associated with the SCL-90-R Global Severity Index (GSI), the overall mental health indicator of CMWs.

Methods

We performed a comprehensive literature search of the major English and Chinese databases (to June 2012). Cross-sectional surveys and case–control studies of CMWs (and controls where appropriate) that reported at least one subscale score of the SCL-90-R were included. Multilevel meta-analysis was used to pool the symptom scores of cross-sectional surveys and mean differences of symptom scores (“Cohen’s d” values) between CMWs and controls of case–control studies. Multilevel meta-analysis with ecological- or study-level covariates was used to explore the associations between variables and SCL-90-R GSI score.

Results

The search yielded 48 cross-sectional surveys (comprising 42,813 CMWs) and seven surveys that included control samples. The pooled psychological symptom scores (95 % confidence interval) of CMWs were statistically higher than those of norms from Chinese general population on all scales of SCL-90-R, except for obsessive–compulsive subscale in study quality subgroup analysis. CMWs also scored statistically higher than those of urban counterpart controls on all scales of SCL-90-R. Multilevel regression meta-analysis model revealed that four covariates that accounted for 33.9 % of SCL-90-R GSI heterogeneity across all surveys, including: “mean age of study sample,” “geographic area,” “per capita GDP,” and “statutory minimum monthly wage” of study site in implementation year.

Conclusion

CMWs have more severe psychological symptoms than the general population, and thus, appear to experience higher level of psychological distress. Macro-economic factors may have impact on the overall mental health of CMWs, but the factors that contribute to mental health and mental distress among CMWs remain to be explored and understood.     

Prospective memory and subjective memory decline: A neuropsychological indicator of memory difficulties in community-dwelling older people

Introduction: Prospective memory difficulties are known to occur in Alzheimer’s disease, and may provide an early indicator of cognitive decline. Older people reporting high levels of subjective memory decline (SMD) but without evidence of cognitive decline on standard neuropsychological tests are increasingly considered at increased risk for Alzheimer’s disease. Therefore, the objective of this study was to investigate whether prospective memory performance is differentially impaired in older people reporting high levels of SMD as compared to a control group. Method: A total of 195 community-dwelling older adults (M_age = 73.48 years) were assessed for self-reported complaints of memory decline and allocated to either a group reporting high levels of SMD (SMD, n = 96) or a healthy control group (HC, n = 99). Groups were assessed on neuropsychological tests, an experimental prospective memory task (focal vs. nonfocal cue conditions), and a naturalistic prospective memory task. Results: The groups did not differ in performance on standard neuropsychological tests of working memory, executive attention, and episodic retrospective memory. Furthermore, on an experimental task of prospective memory (the Supermarket Shopping Trip task), although performance of both groups was better when cues for prospective memory were focal to the ongoing activity (η² = .35), the SMD group were not impaired relative to the control group. On a naturalistic prospective memory task, however, there was a small but significant effect, with the SMD group performing more poorly than the HC group (η² = .02). Conclusions: In older adults with high levels of SMD, naturalistic measures of prospective memory provide an approach to assessing memory performance that can offer a means of investigating the memory complaints of people with SMD. Identifying prospective memory difficulties in SMD also offers a focus for intervention.     

Symptom Checklist 90–Revised in neurological outpatients

The Symptom Checklist 90–Revised (SCL-90-R) is an international, widely used, self-report questionnaire of multidimensional complaints with normative data for healthy control subjects and psychiatric patients. The questionnaire is also often used in neurological patients. Little is known about the amount and pattern of complaints in this group, and normative data are lacking. We therefore analyzed self-reported symptoms on the SCL-90-R of a neurological population (N = 600). Moreover, we compared the answer patterns of five subgroups: neurodegenerative disease, cerebrovascular disease, epilepsy, brain tumor, and traumatic brain injury. Neurological outpatients scored significantly higher in comparison with normative data from healthy control subjects, with most pronounced scores on Inadequacy of Thinking and Acting, Depression, and Somatization (p < .01, effect sizes 1.69, 0.83, and 0.83). No differences between the various pathologies were found. Although it is difficult to determine whether the complaints arise directly from the neurological disease or more indirectly from psychiatric disturbances accompanying the disease, simply comparing a neurological patient to normative data for healthy control subjects can lead to inappropriate classifications. Complaints of our patients should not be directly interpreted as psychopathology. A two-step procedure in which scores on the SCL-90-R are first compared to healthy control subjects and secondly to neurological patients can be helpful in the interpretation.     

The impact of pediatric neuropsychological consultation in mild traumatic brain injury: a model for providing feedback after invalid performance

Objective: In recent years, pediatric practitioners have increasingly recognized the importance of objectively measuring performance validity during clinical assessments. Yet, no studies have examined the impact of neuropsychological consultation when invalid performance has been identified in pediatric populations and little published guidance exists for clinical management. Here we provide a conceptual model for providing feedback after noncredible performance has been detected. In a pilot study, we examine caregiver satisfaction and postconcussive symptoms following provision of this feedback for patients seen through our concussion program. Methods: Participants (N = 70) were 8–17-year-olds with a history of mild traumatic brain injury who underwent an abbreviated neuropsychological evaluation between 2 and 12 months post-injury. We examined postconcussive symptom reduction and caregiver satisfaction after neuropsychological evaluation between groups of patients who were determined to have provided noncredible effort (n = 9) and those for whom no validity concerns were present (n = 61). Results: We found similarly high levels of caregiver satisfaction between groups and greater reduction in self-reported symptoms after feedback was provided using the model with children with noncredible presentations compared to those with credible presentations. Conclusion: The current study lends preliminary support to the idea that the identification and communication of invalid performance can be a beneficial clinical intervention that promotes high levels of caregiver satisfaction and a reduction in self-reported and caregiver-reported symptoms.     

Assessing the criterion validity of four highly abbreviated measures from the Minimal Assessment of Cognitive Function in Multiple Sclerosis (MACFIMS)

Objective: Cognitive dysfunction is prevalent in multiple sclerosis. As self-reported cognitive functioning is unreliable, brief objective screening measures are needed. Utilizing widely used full-length neuropsychological tests, this study aimed to establish the criterion validity of highly abbreviated versions of the Brief Visuospatial Memory Test – Revised (BVMT-R), Symbol Digit Modalities Test (SDMT), Delis–Kaplan Executive Function System (D-KEFS) Sorting Test, and Controlled Oral Word Association Test (COWAT) in order to begin developing an MS-specific screening battery. Method: Participants from Holy Name Medical Center and the Kessler Foundation were administered one or more of these four measures. Using test-specific criterion to identify impairment at both ?1.5 and ?2.0 SD, receiver-operating-characteristic (ROC) analyses of BVMT-R Trial 1, Trial 2, and Trial 1 + 2 raw data (N = 286) were run to calculate the classification accuracy of the abbreviated version, as well as the sensitivity and specificity. The same methods were used for SDMT 30-s and 60-s (N = 321), D-KEFS Sorting Free Card Sort 1 (N = 120), and COWAT letters F and A (N = 298). Results: Using these definitions of impairment, each analysis yielded high classification accuracy (89.3 to 94.3%). Conclusions: BVMT-R Trial 1, SDMT 30-s, D-KEFS Free Card Sort 1, and COWAT F possess good criterion validity in detecting impairment on their respective overall measure, capturing much of the same information as the full version. Along with the first two trials of the California Verbal Learning Test – Second Edition (CVLT-II), these five highly abbreviated measures may be used to develop a brief screening battery.     

Evaluation of performance validity using a Rey Auditory Verbal Learning Test forced-choice trial

Objective: Forced-choice (FC) recognition memory is a common performance validity assessment methodology. This study introduces and evaluates the classification accuracy of a FC recognition trial for the Rey Auditory Verbal Learning Test (RAVLT). Method: The present sample of 122 military veterans (Mean age = 35.4, SD = 9.3) were all administered the RAVLT along with the FC procedure as part of a full neuropsychological protocol. Veterans were assigned to valid (n = 94) or invalid (n = 28) groups based on outcomes of performance validity measures. Results: The FC procedure was found to have strong sensitivity (67.9%) and specificity (92.6%) in predicting validity group status based on a cutoff score of ≤ 13. The FC trial outperformed RAVLT recognition hits (sensitivity = 46.4%, specificity = 91.5%) as a predictor of invalid performance. Conclusions: The RAVLT FC is demonstrated to be an effective measure of performance validity and is recommended for use as an adjunctive trial for the RAVLT.     

Predictors of Suicidal Ideation in People with Epilepsy Living in Korea

Background and Purpose

The risk of suicide or suicide attempts is reported higher in people with epilepsy (PWE) than in the general population. Although epileptic, psychiatric, and psychosocial factors are known risk factors for suicide or suicide attempt, no studies have evaluated the predictors of the severity of suicidal ideation-which is a warning sign for suicide attempts-in PWE. Therefore, we measured the severity of suicidal ideation and its risk factors.

Methods

Consecutive PWE who were medicated with antiepileptic drugs (AEDs) and attended epilepsy clinic were included in the study. The subjects completed self-reported questionnaires, which included the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), Symptom Checklist-90-Revised (SCL-90-R), and Scale for Suicide Ideation-Beck (SSI-Beck). We compared the patients'' demographic and clinical variables, and BDI, BAI, and SCL-90-R scores with their SSI-Beck score, and used our findings to determine the predictors for suicidal ideation.

Results

In total, 257 PWE were enrolled in the study. SSI-Beck scores correlated strongly with several seizure-related variables, duration of education, IQ, BDI and BAI scores, and nine domains of the SCL-90-R questionnaire. However, the strongest predictor for suicidal ideation was BDI score (β=0.41, p<0.001), followed by several SCL-90-R domains, such as obsessive-compulsive (β=-0.39, p<0.001), depression (β=0.38, p<0.001), hostility (β=0.22, p=0.002), paranoid ideation (β=0.17, p=0.01), and IQ (β=-0.10, p=0.017). These variables explained 59% of the variance in the SSI-Beck score. The seizure-related variables that influenced the BDI score were seizure frequency, duration of education, MRI abnormality, and number of AEDs. However, these variables explained only 18% of the variance in the BDI score.

Conclusions

Major risk factors for suicidal ideation in PWE were depressive and psychiatric symptoms rather than seizure-related variables. Therefore, clinicians should focus on screening for depression and other psychiatric problems and treat them appropriately in order to reduce suicidal behavior in PWE. Since seizure-related variables also exhibited a minor role in determining depressive symptoms, stronger seizure-related risk factors for depression should be sought, such as seizure severity or psychosocial factors, to minimize suicidal behavior.     

A clinimetric analysis of the Hopkins Symptom Checklist (SCL-90-R) in general population studies (Denmark,Norway, and Italy)

Background: Although the Symptom Checklist (SCL-90-R) is one of the most widely used self-reported scales covering several psychopathological states, the scalability of the SCL-90-R has been found to be very problematic. Aims: We have performed a clinimetric analysis of the SCL-90-R, taking both its factor structure and scalability (i.e. total scale score a sufficient statistic) into account. Methods: The applicability of the SCL-90-R has been found acceptable in general population studies from Denmark, Norway and Italy. These studies were examined with principal component analysis (PCA) to identify the factor structure. The scalability of the traditional SCL-90-R subscales (i.e. somatization, hostility, and interpersonal sensitivity) as well as the affective subscales (i.e. depression and anxiety and ADHD), were tested by Mokken’s item response theory model. Results: Across the three general population studies the traditional scaled SCL-90-R factor including 83 items was identified by PCA. The Mokken analysis accepted the scalability of both the general factor and the clinical SCL-90-R subscales under examination. Conclusion: The traditional, scaled, general 83 item SCL-90-R scale is a valid measure of general psychopathology. The SCL-90-R subscales of somatization, hostility, and interpersonal sensitivity as well as the affective subscales of depression, anxiety, and ADHD were all accepted by the Mokken test for scalability, i.e. their total scores are sufficient statistics.     

Utility of various WAIS-IV Digit Span indices for identifying noncredible performance validity among cognitively impaired and unimpaired examinees

Objective: Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) Reliable Digit Span (RDS), RDS-revised (RDS-R), and age-corrected scaled score (ACSS) are validated and commonly used embedded performance validity tests (PVTs), though existing validation studies have largely examined younger (approximate ages 19–35) patients with mild traumatic brain injury or those without cognitive impairment. This study compared the classification accuracy of RDS, RDS-R, and ACSS in a mixed clinical sample of relatively older (M age = 54.61) veterans with and without neurocognitive impairment. Method: During a comprehensive neuropsychological evaluation, 113 clinically-referred veterans completed the WAIS-IV Digit Span subtest and the following criterion PVTs: Dot Counting Test, Word Choice Test, and Test of Memory Malingering. Those with ≤1 criterion PVT failure were classified as valid (n = 87), whereas those with ≥2 failures were classified as noncredible (n = 26). Among valid participants, 49% were cognitively impaired. Results: RDS, RDS-R, and ACSS all significantly predicted validity group membership with respective areas under the curve (AUCs) of .79, .81, and .85, and optimal cut scores of RDS ≤ 5, RDS-R ≤ 9, and ACSS ≤ 5. Lower accuracy and AUCs were observed for the valid-cognitively impaired subsample across indices, but to a greater degree for traditional RDS. ACSS evidenced maximal sensitivity/specificity for the total sample (≤5; .62/.87), cognitively unimpaired subsample (≤5; .62/.95), and cognitively impaired subsample (≤4; .39/.86). Conclusions: ACSS yielded better classification accuracy and sensitivity/specificity than RDS and RDS-R. While all three indices have utility as embedded PVTs, ACSS ≤ 5 may be most robust to cognitive impairment while identifying noncredible performance.     

Apolipoprotein E (APOE) ε4 genotype is associated with reduced neuropsychological performance in military veterans with a history of mild traumatic brain injury

Introduction: The purpose of this study was to investigate the effect of the apolipoprotein E (APOE) ε4 allele on neuropsychological functioning in military Veterans with a remote history of mild traumatic brain injury (mTBI).

Method: This cross-sectional study included 99 Veterans (mTBI = 53; military controls, MC = 46) who underwent neuropsychological assessment and APOE genotyping. Three neurocognitive composite scores—memory (α = .84), speed (α = .85), and executive functioning (α = .76)—were computed from 24 norm-referenced variables, and the total number of impaired scores (>1.5 SDs below mean) for each participant was calculated.

Results: Analyses of covariance adjusting for ethnicity and posttraumatic stress disorder (PTSD) symptoms revealed that although no significant differences were observed between mTBI ε4 allele groups on the executive functioning composite (p > .05), mTBI ε4+ Veterans performed more poorly than ε4? Veterans on the memory (p = .045, η_p² = .083) and speed (p = .023, η_p² = .106) composites. Furthermore, Mann–Whitney U tests showed that ε4+ mTBI Veterans displayed a significantly greater number of impaired scores than did ε4? mTBI Veterans (p = .010, r = .355). In contrast, there were no significant differences across any of the cognitive variables between ε4+ and ε4? MCs (all p > .05).

Conclusions: Results suggest that APOE ε4 genotype is related to reduced memory and processingspeed performance, as well as overall cognitive impairment, in those with a history of mTBI, but does not appear to have the same negative effects on cognition in the absence of neurotrauma. Although results are preliminary, the present study advances understanding of genetic influences on cognitive functioning in Veterans with remote mTBIs. Future longitudinal work is needed to elucidate the underlying brain-based mechanisms of ε4 allelic effects on cognitive and clinical outcomes following TBI.     

Vitamin D and executive functioning: Are higher levels better?

Objectives: Insufficiency of 25-hydroxyvitamin D has been associated with cognitive impairment, particularly worse executive functioning. However, it remains unclear whether supratherapeutic levels (≥100 nmol L^–1) are associated with even better performance than sufficient levels (defined as ≥50 nmol L^–1 or even ≥75 nmol L^–1). The current investigation sought to examine this question. Method: Healthy adults (n = 142) were tested on four measures of executive functioning, including verbal fluency, digit span backward, CANTAB® Spatial Working Memory, and One Touch Stockings of Cambridge. A measure of attention (digit span forward) and memory (CANTAB® Verbal Recognition) were also assessed. Based on blood 25-hydroxyvitamin D [25(OH)D] levels, participants were divided into four groups: insufficient (<50 nmol L^–1), low sufficient (50 to <75 nmol L^–1), high sufficient (75 to <100 nmol L^–1), and supratherapeutic (≥100 nmol L^–1). Relationships between vitamin D status and cognition were assessed by analyses of covariance and hierarchical multiple regression, adjusted for age, education, sex, body mass index, mood, and physical activity level. Multivariate regression spline analyses were utilized to investigate nonlinearity. Results: Performance on verbal fluency, but not other measures, differed by vitamin D status, analysis of covariance (ANCOVA), F(3, 127) = 2.70, p = .048; d = 0.50. Specifically, participants with supratherapeutic levels provided a greater number of words (M = 16.1, SE = 1.0) than those with insufficient (M = 12.0, SE = 1.0; p = .007, d = 0.78), low (M = 13.4, SE = 0.7; p = .026, d = 0.51), and high sufficient levels (M = 13.9, SE = 0.9; p = .080, d = 0.42). Similarly, vitamin D status was a significant independent predictor of verbal fluency (p = .025, d = 0.40). Spline analyses revealed that there is a positive, near-linear association between verbal fluency and 25(OH)D levels up to and exceeding 100 nmol L^–1. Discussion: Supratherapeutic levels of vitamin D were associated with significantly better performance on verbal fluency. Importantly, commonly used cutoff levels and sufficiency categories have been based on bone health and optimal levels for cognition are unknown. These findings suggest that levels exceeding 100 nmol L^–1 may be optimal for at least some aspects of executive functioning.