Delis-Kaplan Executive Function System Trail Research Articles

Inferior Prefrontal Cortex Mediates the Relationship between Phosphatidylcholine and Executive Functions in Healthy, Older Adults.

Objectives: This study examines the neural mechanisms that mediate the relationship between phosphatidylcholine and executive functions in cognitively intact older adults. We hypothesized that higher plasma levels of phosphatidylcholine are associated with better performance on a particular component of the executive functions, namely cognitive flexibility, and that this relationship is mediated by gray matter structure of regions within the prefrontal cortex (PFC) that have been implicated in cognitive flexibility.Methods: We examined 72 cognitively intact adults between the ages of 65 and 75 in an observational, cross-sectional study to investigate the relationship between blood biomarkers of phosphatidylcholine, tests of cognitive flexibility (measured by the Delis–Kaplan Executive Function System Trail Making Test), and gray matter structure of regions within the PFC. A three-step mediation analysis was implemented using multivariate linear regressions and we controlled for age, sex, education, income, depression status, and body mass index.Results: The mediation analysis revealed that gray matter thickness of one region within the PFC, the left inferior PFC (Brodmann’s Area 45), mediates the relationship between phosphatidylcholine blood biomarkers and cognitive flexibility.Conclusion: These results suggest that particular nutrients may slow or prevent age-related cognitive decline by influencing specific structures within the brain. This report demonstrates a novel structural mediation between plasma phosphatidylcholine levels and cognitive flexibility. Future work should examine the potential mechanisms underlying this mediation, including phosphatidylcholine-dependent cell membrane integrity of the inferior PFC and phosphatidylcholine-dependent cholinergic projections to the inferior PFC.

Neuropsychological profiles of adults and older adults with HIV

The wider availability of highly active antiretroviral therapy has resulted in a concomitant increase in adults aging with HIV and the persistence of milder forms of neuropsychological impairment in this cohort. This study investigated the differences in neuropsychological functioning between a group of HIV+ adults and older adults and an HIV− matched control group. Participants from a semi-urban community clinic volunteered to participate in the study. The performance of 50 participants (33 HIV+ and 17 HIV−) who met the inclusion criteria were compared on the following measures: Dementia Rating Scale-2, the Stroop Color and Word Test, the Symbol Digits Modalities Test, and the Delis–Kaplan Executive Function System Trail Making Test. The results indicated that the HIV+ in comparison with the HIV− negative group had poorer performance profiles in global cognitive functioning, memory, executive functioning, visuoconstruction ability, psychomotor functioning, and processing speed. The findings suggest that further research in South Africa will contribute to a better understanding of the neuropsychological profiles of adults aging with HIV and inform intervention strategies specific to addressing the mental healthcare needs of this subgroup.

Combined Cognitive-Strategy and Task-Specific Training Affects Cognition and Upper-Extremity Function in Subacute Stroke: An Exploratory Randomized Controlled Trial.

The purpose of this study was to estimate the effect of Cognitive Orientation to Daily Occupational Performance (CO-OP) compared with usual occupational therapy on upper-extremity movement, cognitive flexibility, and stroke impact in people less than 3 mo after stroke. An exploratory, single-blind randomized controlled trial was conducted with people referred to outpatient occupational therapy services at two rehabilitation centers. Arm movement was measured with the Action Research Arm Test, cognitive flexibility with the Delis-Kaplan Executive Function System Trail Making subtest, and stroke impact with subscales of the Stroke Impact Scale. A total of 35 participants were randomized, and 26 completed the intervention. CO-OP demonstrated measurable effects over usual care on all measures. These data provide early support for the use of CO-OP to improve performance and remediate cognitive and arm movement impairments after stroke over usual care; however, future study is warranted to confirm the effects observed in this trial.

The effects of age and physical health on processing speed in HIV

The impact of age and physical health on processing speed was investigated in 42 non-demented HIV+ individuals ranging in age from 30 to 75. We used the Medical Outcomes Study-HIV Healthy Survey (MOS-HIV) to measure self-reported physical health, neuropsychological tests to measure psychomotor and cognitive processing speed (Delis–Kaplan Executive Function System Trail Making Test, Grooved Pegboard Test, letter and category fluency), and a test of the foreperiod effect to measure reaction time under increasing attentional load. Results indicated that aging and worse physical health each independently contributed to slowing on different processing speed measures, while the interaction between aging and physical health did not contribute to processing speed. These findings highlight the importance of considering physical health separately from age when measuring cognitive function in HIV+ adults.

Anterior cingulate cortex mediates the relationship between O3PUFAs and executive functions in APOE e4 carriers.

Introduction: Although diet has a substantial influence on the aging brain, the relationship between biomarkers of diet and aspects of brain health remains unclear. This study examines the neural mechanisms that mediate the relationship between omega-3 polyunsaturated fatty acids (O3PUFAs) and executive functions in at-risk (APOE e4 carriers), cognitively intact older adults. We hypothesized that higher levels of O3PUFAs are associated with better performance in a particular component of the executive functions, namely cognitive flexibility, and that this relationship is mediated by gray matter volume of a specific region thought to be important for cognitive flexibility, the anterior cingulate cortex.Methods: We examined 40 cognitively intact adults between the ages of 65 and 75 with the APOE e4 polymorphism to investigate the relationship between biomarkers of O3PUFAs, tests of cognitive flexibility (measured by the Delis-Kaplan Executive Function System Trail Making Test), and gray matter volume within regions of the prefrontal cortex (PFC).Results: A mediation analysis revealed that gray matter volume within the left rostral anterior cingulate cortex partially mediates the relationship between O3PUFA biomarkers and cognitive flexibility.Conclusion: These results suggest that the anterior cingulate cortex acts as a mediator of the relationship between O3PUFAs and cognitive flexibility in cognitively intact adults thought to be at risk for cognitive decline. Through their link to executive functions and neuronal measures of PFC volume, O3PUFAs show potential as a nutritional therapy to prevent dysfunction in the aging brain.

Neurocognitive Effects of Repetitive Transcranial Magnetic Stimulation in Adolescents with Major Depressive Disorder

Objectives: It is estimated that 30–40% of adolescents with major depressive disorder (MDD) do not receive full benefit from current antidepressant therapies. Repetitive transcranial magnetic stimulation (rTMS) is a novel therapy approved by the US Food and Drug Administration to treat adults with MDD. Research suggests rTMS is not associated with adverse neurocognitive effects in adult populations; however, there is no documentation of its neurocognitive effects in adolescents. This is a secondary post hoc analysis of neurocognitive outcome in adolescents who were treated with open-label rTMS in two separate studies.Methods: Eighteen patients (mean age, 16.2 ± 1.1 years; 11 females, 7 males) with MDD who failed to adequately respond to at least one antidepressant agent were enrolled in the study. Fourteen patients completed all 30 rTMS treatments (5 days/week, 120% of motor threshold, 10 Hz, 3,000 stimulations per session) applied to the left dorsolateral prefrontal cortex. Depression was rated using the Children’s Depression Rating Scale-Revised. Neurocognitive evaluation was performed at baseline and after completion of 30 rTMS treatments with the Children’s Auditory Verbal Learning Test (CAVLT) and Delis–Kaplan Executive Function System Trail Making Test.Results: Over the course of 30 rTMS treatments, adolescents showed a substantial decrease in depression severity. Commensurate with improvement in depressive symptoms was a statistically significant improvement in memory and delayed verbal recall. Other learning and memory indices and executive function remained intact. Neither participants nor their family members reported clinically meaningful changes in neurocognitive function.Conclusion: These preliminary findings suggest rTMS does not adversely impact neurocognitive functioning in adolescents and may provide subtle enhancement of verbal memory as measured by the CAVLT. Further controlled investigations with larger sample sizes and rigorous trial designs are warranted to confirm and extend these findings.

Genetic architecture of the Delis-Kaplan executive function system Trail Making Test: Evidence for distinct genetic influences on executive function.

To examine how genes and environments contribute to relationships among Trail Making Test (TMT) conditions and the extent to which these conditions have unique genetic and environmental influences. Participants included 1,237 middle-aged male twins from the Vietnam Era Twin Study of Aging. The Delis-Kaplan Executive Function System TMT included visual searching, number and letter sequencing, and set-shifting components. Phenotypic correlations among TMT conditions ranged from 0.29 to 0.60, and genes accounted for the majority (58-84%) of each correlation. Overall heritability ranged from 0.34 to 0.62 across conditions. Phenotypic factor analysis suggested a single factor. In contrast, genetic models revealed a single common genetic factor but also unique genetic influences separate from the common factor. Genetic variance (i.e., heritability) of number and letter sequencing was completely explained by the common genetic factor while unique genetic influences separate from the common factor accounted for 57% and 21% of the heritabilities of visual search and set shifting, respectively. After accounting for general cognitive ability, unique genetic influences accounted for 64% and 31% of those heritabilities. A common genetic factor, most likely representing a combination of speed and sequencing, accounted for most of the correlation among TMT 1-4. Distinct genetic factors, however, accounted for a portion of variance in visual scanning and set shifting. Thus, although traditional phenotypic shared variance analysis techniques suggest only one general factor underlying different neuropsychological functions in nonpatient populations, examining the genetic underpinnings of cognitive processes with twin analysis can uncover more complex etiological processes.

Normative Adjustments to the D-KEFS Trail Making Test: Corrections for Education and Vocabulary Level

The Delis-Kaplan Executive Function System (D-KEFS) Trail Making Test (TMT), a modification of the original TMT, was created to isolate set-shifting (Letter–Number Switching) from other component skills. This was accomplished by including four baseline conditions (Visual Scanning, Number Sequencing, Letter Sequencing, and Motor Speed) and by placing equal numbers of stimuli in the three sequencing conditions. Given that some studies with the original TMT demonstrated a significant effect of education and intellectual functioning on performance, we utilized the D-KEFS national standardization sample to examine the effects of education and vocabulary level—i.e., Vocabulary subtest from the Wechsler Abbreviated Scale of Intelligence (WASI)—on the D-KEFS TMT. The results indicate a significant effect of these variables on each D-KEFS TMT condition. Normative tables for education- and vocabulary-adjusted scaled scores based on the database from the D-KEFS national normative study were generated.

Nonclinical Obsessive-Compulsive Symptoms and Executive Functions in Schizophrenia

Nonclinical Obsessive-Compulsive Symptoms and Executive Functions in Schizophrenia

The Relationship Between Pain and Mental Flexibility in Older Adult Pain Clinic Patients

Persistent pain and cognitive impairment are each common in older adults. Mental flexibility, memory, and information-processing speed may be particularly vulnerable in the aging brain. We investigated the effects of persistent pain on these cognitive domains among community-dwelling, nondemented older adults. Older Adult Pain Management Program. A total of 56 new patients (mean age 76.1 years) were recruited to describe 1) rates of persistent pain conditions and pain intensity; 2) cognition (mental flexibility, short-term memory, and psychomotor speed); 3) severity of depression; and 4) sleep quality. All patients had nonmalignant pain for at least 3 months. Pain intensity was measured with the McGill Pain Questionnaire and depression severity with the 17-item Hamilton Rating Scale for Depression. Cognition was assessed with 1) Mini-Mental State Exam; 2) Number-Letter-Switching and Motor Speed subtests of the Delis-Kaplan Executive Function System Trail Making Test; 3) Digit Symbol Subtest (DSST) of the Wechsler Adult Intelligence Scales-III; and 4) free and paired recall of the DSST digit-symbol pairs. Multiple linear regression modeled whether these variables predicted poorer cognitive outcomes, after adjusting for the effects of opioids, sleep impairment, depression, medical comorbidity, and years of education. In univariate analysis, pain severity was associated with a greater impairment on number-letter switching (r = -0.42, P = 0.002). This association remained after adjusting for the effects of depression, sleep, medical comorbidity, opioid use, and years of education (t = -1.97, P = 0.056). In community dwelling older adults, neither pain nor mood was associated with measures of short-term memory or information-processing speed. However, pain severity was associated with decreased performance on a test of number-letter switching, indicating a relationship between pain and mental flexibility.