Establishing construct validity of neuropsychological tests in cancer survivors.

OBJECTIVE: Cancer-related cognitive impairments (CRCI) are frequently reported among cancer survivors, and attention is the most frequently assessed cognitive domain in CRCI. However, there is no consensus as to whether attention is impaired. We suggest that a major reason for this lack of agreement is a lack of construct validity for neuropsychological attention tests. We propose to assess the construct validity of neuropsychological attention tests with respect to experimental paradigms from cognitive psychology. METHODS: Self-reported cancer survivors (N = 314) completed an online battery comprising six experimental attention paradigms and eight neuropsychological tests. Confirmatory factor analysis was used to evaluate the fit of five models derived from a general population sample (N = 636) in a previous study (M. Treviño, Cogn Res Princ Implic, in press). We then subjected the best-fitting model to a measurement invariance analysis. RESULTS: The best-fitting model was a six intercorrelated factor structure, comprising Capacity, Search, Digit Span, Arithmetic, Sustained Attention, and Flanker Interference factors. Configural and weak invariance held, indicating that the factor loadings were invariant across groups. Strong invariance, indicating that intercepts were also invariant, held except for the Approximate Number Sense test. CONCLUSIONS: According to our factor model, Spatial Span and Digit Symbol Coding measure attentional capacity, while the Trail Making Test (A&B) and Letter Cancellation tests measure visual search ability. However, Digit Span and Arithmetic tests do not measure attention. We hope that these results will lead to better scientific models, better patient education, and, ultimately, improved outcomes for survivors.

Patient and service-related barriers and facitators to the acceptance and use of interventions to promote communication in health and social care: a realist review.

BACKGROUND: More people living into old age with dementia. The complexity of treatment and care, particularly those with multiple health problems, can be experienced as disjointed. As part of an evaluation of a 'healthcare passport' for people living with dementia we undertook a realist review of communication tools within health and social care for people living with dementia. AIMS: To explore how a 'healthcare passport' might work in the 'real world' of people living with dementia through a better understanding of the theoretical issues related to, and the contextual issues that facilitate, successful communication. METHODS: A realist review was considered the most appropriate methodology to inform the further development and evaluation of the healthcare passport. We undertook a purposive literature search related to communication tools to identify (a) underlying programme theories; (b) published reports and papers on their use in various healthcare settings; (c) evidence on barriers and facliitators of their use. RESULTS: Communication tools were noted as a way of improving communication and outcomes through: (1) improvement of service user autonomy; (2) strengthening the therapeutic alliance; and (3) building integrated care. However, while intuitively perceived to of benefit, evidence on their use is limited and key barriers to their acceptance and use include: (1) difficulties in clearly defining purpose, content, ownership and usage; (2) understanding the role of family caregivers; and (3) preparation among healthcare professionsals. CONCLUSION: Patient-held communication tools may be helpful to some people living with dementia but will require considerable preparation and engagement with key stakeholders.

Modeling TNT ignition.

A 2,4,6-trinitrotoluene (TNT) ignition model was developed using data from multiple sources. The one-step, first-order, pressure-dependent mechanism was used to predict ignition behavior from small- and large-scale experiments involving significant fluid motion. Bubbles created from decomposition gases were shown to cause vigorous boiling. The forced mixing caused by these bubbles was not modeled adequately using only free liquid convection. Thorough mixing and ample contact of the reactive species indicated that the TNT decomposition products were in equilibrium. The effect of impurities on the reaction rate was the primary uncertainty in the decomposition model.

Unconscious, stimulus-dependent priming and conscious, percept-dependent priming with chromatic stimuli.

Using metacontrast masking to suppress the conscious registration of a prime stimulus, Breitmeyer, Ro, and Singhal (2004) showed that color priming produced by a masked prime disk occurs at unconscious stimulus-dependent rather than at percept-dependent levels of visual processing. The current set of experiments compares this type of unconscious stimulus-dependent priming to conscious priming produced by a prime that, in two separate ways, is rendered visible and thus activates percept-dependent visual processes. The results indicate that while the masked prime again acts at a stimulus-dependent level of processing, the unmasked, visible primes additionally act at a later percept-dependent level of processing.

Target recovery in metacontrast: the effect of contrast.

The visibility of a target stimulus (T) can be reduced by an aftercoming and spatially non-overlapping mask stimulus (M1), a phenomenon known as metacontrast masking. Interestingly, the visibility of the masked target can be recovered when a secondary mask (M2) is added to the T-M1 sequence. We analyzed a computational model of retino-cortical dynamics (RECOD) and derived the prediction that contrast dependence of metacontrast and target recovery should parallel the contrast dependence of afferent magnocellular and parvocellular pathways, respectively. In a psychophysical experiment, we tested this prediction by systematically varying (a) M2's contrast and (b) the M1-M2 onset asynchrony (SOA). At the optimal M1-M2 SOA, target recovery effect increased with M2's contrast without saturating, but at the optimal M1-M2 metacontrast SOA, reduction of M1's visibility saturated very rapidly as M2's contrast increased. Quantitative comparisons of psychophysical results with model simulations provide support for our prediction. We conclude that metacontrast masking is driven by signals originating from the magnocellular pathway and target recovery in metacontrast is driven by signals originating from the parvocellular pathway.

Meta- and paracontrast reveal differences between contour- and brightness-processing mechanisms.

We investigated meta- and paracontrast masking using tasks requiring observers to judge the surface brightness or else the contours of target stimuli. The contour task revealed strongest metacontrast at SOAs shorter than those obtained for the brightness task. Paracontrast revealed related temporal differences between the tasks. Additionally, the paracontrast results support the existence not only of prolonged inhibitory effects but also of facilitatory effects. The combined results comport with the existence of cortical mechanisms for: (i) fast contour processing, (ii) slow surface-brightness processing, (iii) prolonged inhibition, and (iv) facilitation.

Outpatient laparoscopic Nissen fundoplication.

Gastroesophageal reflux disease affects more than 40% of Americans, causing heartburn and reflux of gastric contents into the esophagus when bending or lying down. Lifestyle modification, such as weight loss and a diet rich in protein and low in fat and glucose, should increase the patient's resting lower esophageal sphincter pressure. Avoiding exacerbating substances, such as mint, chocolate, alcohol, and tobacco, also may reduce symptoms. Medications may be prescribed to reduce persistent symptoms, although no medication currently available cures the disease process. Patients who need antireflux medication regularly for four to six weeks or more may be candidates for laparoscopic Nissen fundoplication. Patients who do not want to take antireflux medication for the rest of their lives, cannot afford the medication for an extended period of time, or suffer significant side effects from the medication also are candidates. This article describes performing Nissen fundoplication laparoscopically on an outpatient basis. The average length of hospital stay has been decreased to two to three hours when performed laparoscopically on an outpatient basis from 10 days for the open procedure and two to three days when performed laparoscopically on an inpatient basis. The incidence of recurrent heartburn is less than 2% when the procedure is performed laparoscopically and does not appear to be clinically significant.