The primary cognitive deficit among males with fragile X-associated tremor/ataxia syndrome (FXTAS) is a dysexecutive syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS) is a neurodegenerative disorder associated with a premutation trinucleotide repeat expansion in the fragile X mental retardation 1 gene. Symptoms include gait ataxia, action tremor, and cognitive impairment. The objectives of the study were to clarify the nature of the dysexecutive syndrome observed in FXTAS and to assess the contribution of executive impairment to deficits in nonexecutive cognitive functions. Compared to controls, men with FXTAS demonstrated significant executive impairment, which was found to mediate group differences in most other cognitive abilities. Asymptomatic premutation carriers performed similarly to controls on all but two measures of executive functioning. These findings suggest that the impairment of nonexecutive cognitive skills in FXTAS is in large part secondary to executive dysfunction.

The impact of executive cognitive functioning on rates of smoking cessation in the San Luis Valley Health and Aging Study

Cigarette smoking is one of the leading preventable causes of death. Previous research has shown that many common smoking cessation interventions are effective with older smokers; a few interventions have been tailored to this population. To our knowledge, however, no smoking cessation research or interventions targeted at older adults have addressed the influence of cognition on successful smoking cessation. We hypothesized that impairment of executive cognitive functioning (ECF), which is relatively prevalent among older adults, would negatively influence smoking cessation rates among older smokers. The relationship of ECF to smoking cessation was examined in a population-based sample of 1,338 community-dwelling older persons in Colorado's San Luis Valley, 204 of whom were current smokers. As predicted, current ECF did not predict early smoking behaviour, but was a significant predictor of successful smoking cessation. Older persons suffering from executive dysfunction were less likely to have quit smoking than were their cognitively intact counterparts (OR = 1.10, 95% CI 1.04-1.17, P < 0.01). Among those with normal ECF, 73.7% had quit smoking, compared with 65.1% of participants showing any level of ECF impairment. Limiting the sample to individuals who were active smokers at or after the age of 65, when executive impairment is relatively common, produced similar results. Individuals with better executive functioning were more likely to have quit smoking (OR = 1.12, 95% CI 1.02-1.23, P = 0.02).

Simulated neural networks to predict outcomes, costs, and length of stay among orthopedic rehabilitation patients

Our purpose was to develop a set of simulated neural networks that would predict functional outcomes, length of stay, and costs among orthopedic patients admitted to an inpatient rehabilitation hospital. We used retrospective data for a sample of 387 patients between the ages of 60 and 89 who had been admitted to a single rehabilitation facility over a period of 12 months. Using age and data on functional capacity at admission from the Functional Independence Measure, we were successful in constructing networks that were 86%, 87%, and 91% accurate in predicting functional outcome, length of stay, and costs to within +/- 15% of the actual value. In each case the accuracy of the network exceeded that of a multiple regression equation using the same variables. Our results show the feasibility of using simulated neural networks to predict rehabilitation outcomes, and the advantages of neural networks over conventional linear models. Networks of this kind may be of significant value to administrators and clinicians in predicting outcomes and resource usage as rehabilitation hospitals are faced with capitation and prospective payment schemes.

Endorphins and placebo fear reduction

This study examined whether endorphins play a role in placebo fear reduction in addition to their apparent mediation of placebo analgesia. 27 female undergraduate students were intravenously administered either saline or the endorphin antagonist, naloxone, under double-blind conditions prior to exposure to a nonspecific analogue treatment for snake fear. Analysis indicated that the two groups of subjects performed comparably and significantly better than no-treatment controls on posttest measures of self-efficacy, self-rated fear, and approach toward a live, harmless snake. These preliminary findings suggest that a mechanism other than endorphin release underlies fear reduction in psychological placebo treatments.