IQ-based norms for highly intelligent adults

Detecting cognitive decline in high-functioning older adults: The relationship between subjective cognitive concerns, frequency of high neuropsychological test scores, and the frontoparietal control network

OBJECTIVE

Neuropsychologists have difficulty detecting cognitive decline in high-functioning older adults because greater neurological change must occur before cognitive performances are low enough to indicate decline or impairment. For high-functioning older adults, early neurological changes may correspond with subjective cognitive concerns and an absence of high scores. This study compared high-functioning older adults with and without subjective cognitive concerns, hypothesizing those with cognitive concerns would have fewer high scores on neuropsychological testing and lower frontoparietal network volume, thickness, and connectivity.

METHOD

Participants had high estimated premorbid functioning (e.g., estimated intelligence ≥75th percentile or college-educated) and were divided based on subjective cognitive concerns. Participants with cognitive concerns (n = 35; 74.0 ± 9.6 years old, 62.9% female, 94.3% White) and without cognitive concerns (n = 33; 71.2 ± 7.1 years old, 75.8% female, 100% White) completed a neuropsychological battery of memory and executive function tests and underwent structural and resting-state magnetic resonance imaging, calculating frontoparietal network volume, thickness, and connectivity.

RESULTS

Participants with and without cognitive concerns had comparable numbers of low test scores (≤16th percentile), p = .103, d = .40. Participants with cognitive concerns had fewer high scores (≥75th percentile), p = .004, d = .71, and lower mean frontoparietal network volumes (left: p = .004, d = .74; right: p = .011, d = .66) and cortical thickness (left: p = .010, d = .66; right: p = .033, d = .54), but did not differ in network connectivity.

CONCLUSIONS

Among high-functioning older adults, subjective cognitive decline may correspond with an absence of high scores on neuropsychological testing and underlying changes in the frontoparietal network that would not be detected by a traditional focus on low cognitive test scores.

Neuropsychological normative standards for late career physicians

Objective: In the context of an aging, vital physician workforce, there is clear value in establishing a specialized neuropsychological normative dataset for the evaluation of late career physicians practicing clinical medicine. Methods: Physicians aged 60 and over in active clinical practice at 3 major medical centers in North Carolina were recruited to complete a comprehensive neuropsychological test battery. Results: The sample (n = 100) was aged 60-78. Reflecting medical school distributions for this age group, the sample was mostly male (76%) and was fairly racially homogenous (96% White). To amplify utility of the dataset, data were obtained for several measures across neurocognitive domains. Results are presented in percentile bands stratified by age and sex where needed, and regression formulas are presented for predictive precision for measures where both age and sex predicted performance. Important distinctions between our sample, the general population, and current comparative demographic norms were also confirmed. Conclusions: Here we present a preliminary normative dataset on a comprehensive neuropsychological test battery for late career physicians, the HEATS norms for highly educated aging treaters. These standards facilitate accurate, objective cognitive measurement as a part of clinical diagnostic and capacity evaluations. Co-norming the battery in a single, specialized sample further augments its utility in characterizing cognition. Future work to enhance the dataset to be maximally applicable across demographic groups is anticipated, as is research to explore the relationship between these standards and professional performance outcomes.

Neuropsychological and resting-state electroencephalographic markers of older adult neurocognitive adaptability

OBJECTIVE

This study was undertaken to explore multimethod neurocognitive screening tools to aid in detection of older adults who may be at heightened risk of pathological cognitive decline (preclinical dementia). In so doing, this study advances the theoretical conceptualization of neurocognitive adaptability in the context of aging and dementia.

METHOD

This article reports original data from the baseline measurement occasion of a longitudinal study of healthy, community-dwelling older adults from the Victoria, British Columbia region. Participants were diagnosed as normal, subtle decline, or mild cognitive impairment according to actuarial neuropsychological criteria (adjusted for age only or adjusted for age and premorbid IQ). Diagnostic classification was employed to illustrate group differences in a novel metric of multi-timescale neural adaptability derived from 4-min of resting-state electroencephalographic data collected from each participant (immediately following their neuropsychological evaluation).

RESULTS

Prior findings were replicated; adjusting raw neuropsychological test scores for individual differences in estimated premorbid IQ appeared to increase the sensitivity of standardized clinical tasks to subtle cognitive impairment. Moreover, and consistent with prior neuroscientific research, timescale-specific (i.e. at ∼12-20 ms timescales) differences in resting-state neural adaptability appeared to characterize groups who differed in terms of neuropsycholgoical diagnostic classification.

CONCLUSIONS

Recently proposed actuarial neuropsychological criteria for subtle cognitive decline identify older adults who show timescale-specific changes in resting brain function that may signal the onset of preclinical dementia. The subtle decline stage may represent a critical inflection point-partial loss of neurocognitive adaptability-on a pathological aging trajectory. These findings illustrate areas of potential future development in neurocognitive health care.

Reducing case ascertainment costs in U.S. population studies of Alzheimer's disease, dementia, and cognitive impairment-Part 2

Dementia of the Alzheimer's type (DAT) is a major public health threat in developed countries where longevity has been extended to the eighth decade of life. Estimates of prevalence and incidence of DAT vary with what is measured, be it change from a baseline cognitive state or a clinical diagnostic endpoint, such as Alzheimer's disease. Judgment of what is psychometrically "normal" at the age of 80 years implicitly condones a decline from what is normal at the age of 30. However, because cognitive aging is very heterogeneous, it is reasonable to ask "Is 'normal for age' good enough to screen for DAT or its earlier precursors of cognitive impairment?" Cost containment and accessibility of ascertainment methods are enhanced by well-validated and reliable methods such as screening for cognitive impairment by telephone interviews. However, focused assessment of episodic memory, the key symptom associated with DAT, might be more effective at distinguishing normal from abnormal cognitive aging trajectories. Alternatively, the futuristic "Smart Home," outfitted with unobtrusive sensors and data storage devices, permits the moment-to-moment recording of activities so that changes that constitute risk for DAT can be identified before the emergence of symptoms.

Accounting for estimated IQ in neuropsychological test performance with regression-based techniques

Regression-based normative techniques account for variability in test performance associated with multiple predictor variables and generate expected scores based on algebraic equations. Using this approach, we show that estimated IQ, based on oral word reading, accounts for 1-9% of the variability beyond that explained by individual differences in age, sex, race, and years of education for most cognitive measures. These results confirm that adding estimated "premorbid" IQ to demographic predictors in multiple regression models can incrementally improve the accuracy with which regression-based norms (RBNs) benchmark expected neuropsychological test performance in healthy adults. It remains to be seen whether the incremental variance in test performance explained by estimated "premorbid" IQ translates to improved diagnostic accuracy in patient samples. We describe these methods, and illustrate the step-by-step application of RBNs with two cases. We also discuss the rationale, assumptions, and caveats of this approach. More broadly, we note that adjusting test scores for age and other characteristics might actually decrease the accuracy with which test performance predicts absolute criteria, such as the ability to drive or live independently.

Begabungsdiagnostik mit dem Grundintelligenztest (CFT 20-R)

Zusammenfassung. Der CFT 20-R ist ein in der psychologischen Praxis häufig eingesetzter Test zur Diagnostik der fluiden Intelligenz. Er dient damit auch zur Diagnose von Hochbegabung. Gegenstand dieses Artikels ist die psychometrische Überprüfung der Kurzform 1 des Grundintelligenztests (CFT 20-R; Weiß, 2006 ) hinsichtlich der Messäquivalenz des Verfahrens zwischen normal- und höher begabten Schülern. Berichtet werden Ergebnisse auf Item- sowie Subtestebene. Eine Stichprobe von insgesamt N = 1886 Haupt-, Real- sowie Gymnasialschülern beiderlei Geschlechts bearbeitete die Kurzform 1 des CFT 20-R. Mittels DIF-Analysen (Itemebene) kann beim Vergleich von höher (IQ ≥ 120) sowie normal begabten Schülern (IQ < 120) gezeigt werden, dass größtenteils Messäquivalenz hinsichtlich der Itemschwierigkeiten, weniger hinsichtlich der Trennschärfen vorliegt. Die Messäquivalenz auf der Ebene der Subtests ist hoch. Das Verfahren kann damit im Rahmen eines ersten (Hoch-)Begabungsscreenings gut eingesetzt werden.

Cognitive status impacts age-related changes in attention to novel and target events in normal adults

In this study, the authors investigated the relationship between the cognitive status of normal adults and age-related changes in attention to novel and target events. Old, middle-age, and young subjects, divided into cognitively high and cognitively average performing groups, viewed repetitive standard stimuli, infrequent target stimuli, and unique novel visual stimuli. Subjects controlled viewing duration by a button press that led to the onset of the next stimulus. They also responded to targets by pressing a foot pedal. The amount of time spent looking at different kinds of stimuli served as a measure of visual attention and exploratory activity. Cognitively high performers spent more time viewing novel stimuli than cognitively average performers. The magnitude of the difference between cognitively high and cognitively average performing groups was largest among old subjects. Cognitively average performers had slower and less accurate responses to targets than cognitively high performers. The results provide strong evidence that the link between engagement by novelty and higher cognitive performance increases with age. Moreover, the results support the notion of there being different patterns of normal cognitive aging and the need to identify the factors that influence them.