Changes in cognitive function from presurgery to 4 months postsurgery in individuals undergoing dysvascular amputation.

OBJECTIVE: To describe cognition among individuals with new amputations at 3 time points: presurgical, 6 weeks postamputation, and 4 months postamputation. DESIGN: Prospective cohort. SETTING: Medical centers. PARTICIPANTS: Referred sample Veterans who were primarily men (N=80) experiencing their first lower extremity amputation as a result of complications of diabetes mellitus or peripheral arterial disease. Patients were screened for the absence of gross cognitive impairment using the Short Portable Mental Status Questionnaire (SPMSQ). Of those 87 individuals who were eligible, 64% enrolled; 29 were enrolled presurgically and have cognitive data for all 3 time points, and 58 were enrolled postamputation. Eighty of the 87 individuals enrolled by 6 weeks remained enrolled at 4 months. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Demographic and general health information, general mental status (SPMSQ), and 4 brief, well-established neuropsychological measures. RESULTS: Most mean neuropsychological test scores fell in the low average or average range. For most participants, overall cognitive status improved from pre- to postsurgery and then remained stable between 6 weeks and 4 months. There were significant improvements between pre- and postsurgical test scores in verbal learning and memory, and these remained unchanged between 6 weeks and 4 months. Better 4 month cognitive performance was associated with higher perceived general health. CONCLUSIONS: Overall cognitive performance is poorest presurgically. Though there is improvement between pre- and postamputation, cognition appears generally stable between 6 weeks and 4 months.

Effects of drug countermeasures for space motion sickness on working memory in humans.

Space motion sickness (SMS) is a problem during the first 72 h of space flight and during transitions from different gravity environments. There currently are no effective drug countermeasures for SMS that also accommodate the retention of optimal cognitive function. This creates a dilemma for astronauts because cognitive skills are particularly important during gravity transitions (e.g., take-off and landing). To quantify the cognitive side effects of potential drug countermeasures, an automated delayed matching-to-sample (DMTS) procedure was used to assess visual working memory before and after drug countermeasures (meclizine 25 mg, scopolamine 0.4 mg, promethazine 25 mg, or lorazepam 1 mg, given orally approximately 45 min prior to testing) and/or the induction of SMS by vestibular stimulation in a rotary chair (spinning). Sixty-seven normal healthy volunteers (mean age, in years, 26.6+/-4.8 S.D.; 24 females and 43 males) each participated in two test sessions, one 'off' drug and one 'on' drug. Spinning by itself significantly decreased task accuracy (Acc) and choice response speed, especially at longer recall delays. Meclizine alone had no effect on Acc or speed with or without spinning. Scopolamine alone decreased Acc, and with spinning, slowed speed. Promethazine alone had no adverse effect, but combined with spinning, decreased Acc and speed. Lorazepam alone decreased speed, and with spinning, decreased Acc. The data suggest that, at clinically useful doses, the rank order of the drugs with the best cognitive profiles is meclizine>scopolamine>promethazine>lorazepam.

Developmental aspects of timing behavior in children.

This research examined the association of age, sex, and intelligence on the performance of a time production (temporal response differentiation, TRD) task. Variations of this task have been used extensively with both animals and humans to study factors that affect aspects of timing ability. The participants in this study (720 children, ages 5 to 13 years) were required to hold down a response lever for at least 10 s, but no more than 14 s, to receive a nickel. Older children made more correct lever holds and exhibited less variability in the duration of their lever holds than did the younger children. Boys and girls performed similarly on this task, whereas children with higher IQs made more correct lever holds. Young children with below average IQs exhibited increased variability in lever hold duration compared with young children with average and above average IQs. The results of this study illustrate that both age and intelligence influence timing ability. The use of this timing task in children, which also has been widely used in animal models, provides unique opportunities for interspecies comparisons.

Stimulant medication improves recognition memory in children diagnosed with attention-deficit/hyperactivity disorder.

The effect of stimulant medication on recognition memory was examined in 18 children with attention-deficit/hyperactivity disorder (ADHD). Recognition memory was assessed using a delayed matching-to-sample task at 6 delays ranging from 1 to 32 s. Each child was tested on 2 separate occasions, once 60 to 90 min after taking stimulant medication and the other at least 18 hr after taking medication. Children performed significantly better on medication than off. Stimulant administration significantly increased accuracy and the number of nickel reinforcers earned. Decreases in observing response latency and correct choice response latency occurred after taking stimulant medication. The results indicate that stimulant medication improved recognition memory for children with ADHD.