Khamis Abu-Hasaballah

White matter abnormalities in mobility-impaired older persons

Objective: To investigate the relationship between white matter abnormalities and impairment of gait and balance in older persons. Methods: Quantitative MRI was used to evaluate the brain tissue compartments of 28 older individuals separated into normal and impaired groups on the basis of mobility performance testing using the Short Physical Performance Battery. In addition, individuals were tested on six indices of gait and balance. For imaging data, segmentation of intracranial volume into four tissue classes was performed using template-driven segmentation, in which signal-intensity–based statistical tissue classification is refined using a digital brain atlas as anatomic template. Results: Both decreased white matter volume, which was age-related, and increased white matter signal abnormalities, which were not age-related, were observed in the mobility-impaired group compared with the control subjects. The average volume of white matter signal abnormalities for impaired individuals was nearly double that of control subjects. Conclusions: This cross-sectional study suggests that decreased white matter volume is age-related, whereas increased white matter signal abnormalities are most likely to occur as a result of disease. Both of these changes are independently associated with impaired mobility in older persons and therefore likely to be additive factors of motor disability.

Using daily interactive voice response technology to measure drinking and related behaviors in a pharmacotherapy study

BACKGROUND Interactive voice response technology (IVR) allows investigators to collect daily measures of drinking, medication adherence, mood, and other treatment-relevant variables that may change day to day during a clinical trial. Despite these advantages, no published studies have used IVR in alcohol pharmacotherapy trials. METHODS Subjects provided daily data via IVR during the 12-week treatment period. Seven subjects completed the trial. RESULTS We found a high level of participant adherence to the IVR protocol, higher levels of drinking reported by IVR than by a commonly used recall method, and distinct within-day associations between daily mood and alcohol consumption: these could not be obtained through traditional assessment methods. CONCLUSIONS IVR seems to be feasible for the collection of daily indicators of treatment outcomes and processes in pharmacotherapy studies among problem drinkers.

Stance perturbation-evoked potentials in old people with poor gait and balance.

OBJECTIVE Cerebral cortical potentials can be evoked by stance perturbation, and there is speculation that they represent the activation of supraspinal centers in preparation for the control and coordination of motor movements that maintain balance. We sought to determine if these potentials differed in old people at risk of falls. METHODS Cortical potentials were generated by the sudden forward translation of a weight-bearing platform in 8 healthy young subjects and in 33 old subjects stratified by their functional capacity. Dependent measures were compared with non-parametric tests of significance. RESULTS Perturbing the stance of young subjects produced a biphasic scalp potential centered at the vertex with an early positive peak at 60 ms and a larger, 45 microV, negative peak at 123 ms. In old subjects the response was delayed and the vertex-negative component was smaller and bifid. The interval between the two components of the negative peak was prolonged in a subgroup of old subjects with reduced mobility. CONCLUSIONS Delays in sensory conduction may play a role in subsequent maladaptive motor responses to stance perturbation that can result in falls and injury in old people.

The idiographic study of inconsistent condom use behavior of persons living with HIV.

Abstract A pilot study was conducted to assess the feasibility of using, in a multiply disadvantaged population, an electronic daily diary to test hypotheses linking affective states to variability in psychosocial determinants of condom use. Twenty-one mostly non-Caucasian individuals reporting profound economic disadvantage, heavy alcohol use and HIV infection completed a 5–7 minute interactive voice response (IVR) telephone-based survey daily for three weeks. Potentially affect-related within-person variability was observed in HIV-preventive attitudes, intentions and self-efficacy. Surprisingly, in this sample, HIV-preventive attitudes, intentions and self-efficacy exhibited as much, or greater, variability within persons as compared to between persons. Positive affect was found to significantly co-vary with self-efficacy to practice safer sex B=0.20, t (199)=2.14, p=0.03. For each unit increase in daily positive affect, daily self-efficacy increased by 0.20. Results suggest that a daily diary methodology is both feasible in a high-risk population and may offer new insights into understanding unprotected sexual behavior.

Quantitative analysis of long-term potentiation in the hippocampal dentate gyrus of the freely-moving 15-day-old rat

The magnitude and duration of long-term potentiation (LTP) of perforant path/dentate granule cell synapses was examined in freely moving rats beginning at 15 days of age. Measures of dentate granule cell population EPSP slope and population spike amplitude (PSA) obtained before and after tetanization were used to evaluate the level of LTP. Tetanization resulted in significant enhancement of both the population EPSP slope (approximately +75%) and PSA (approximately +40%) measures. This enhancement was maintained without significant change for 18 h, after which both measures began a steady and continuous rise. Daily input/output response measures from age-matched nontetanized animals were used to factor out enhancement related to normal development. Under this schema, tetanization-induced enhancement of both EPSP slope and PSA measures decayed slowly, beginning 18-24 h after tetanization, returning to baseline 5 days after tetanization. Enhancement obtained from 90-day-old animals decayed to baseline 24 h after tetanization. The longer duration of LTP obtained from preweanlings is discussed with regard to the development of inhibitory systems modulating granule cell excitability.

Association between interactive voice response adherence and subject retention in a randomized controlled trial

INTRODUCTION Interactive voice response (IVR) technology uses the telephone to collect patient reports. This study examined whether IVR adherence during a year-long clinical trial was related to subject retention in the trial. METHODS As part of a randomized, double-blind, placebo-controlled study of daily multivitamin supplementation for recurrent aphthous stomatitis, 160 study participants were asked to make 1 weekly IVR call for the one-year study duration. RESULTS The 114 subjects who completed the study made 90.5% of their expected number of IVR calls, as compared to 55.7% of expected calls made by the 46 subjects who withdrew prematurely (p<0.001). Subjects who successfully completed the study were also more likely to initiate their IVR calls as compared to subjects who withdrew from the study (p<0.001). A multivariable model incorporating different adherence variables was able to successfully predict retention status of more than 80% of subjects. IVR adherence during the first few weeks of study participation was strongly predictive of subsequent retention and successful completion of this one-year study. DISCUSSION Subjects who withdrew prematurely had more missing data than study completers, even after accounting for period of study participation, potentially introducing bias into IVR results. Sub-optimal adherence to weekly IVR might provide an early signal of subsequent premature withdrawal in clinical trials. IVR adherence could be used as a screening tool during a trial period, to identify subjects most likely to stay on long clinical trials. CONCLUSION IVR adherence may be useful in anticipating retention in long-term clinical studies.