Predicting response of older adults to mnemonic training: who will benefit?

OBJECTIVES: To identify profiles of subjects who respond to mnemonic training for serial word and proper name recall. DESIGN: Analysis of J. O. Brooks et al.'s (1999) mnemonic training data using Quality Receiver Operating Characteristic (QROC) and longitudinal regression analyses (LRA). SETTING: Community. PARTICIPANTS: 224 community-dwelling adults 55 years of age and older who wished to improve their memory. MEASUREMENTS: Performance on serial word and proper name tests; performance on cognitive ability tests. RESULTS: Although the QROC and LRA identified several common predictors (baseline performance, mental rotation ability, and paired associate learning), the QROC identified additional predictors and cognitive ability profiles associated with successful response. CONCLUSIONS: Similar degrees of response to mnemonic training are associated with heterogeneous cognitive profiles. This finding highlights the fact that participants rely on a variety of abilities to derive benefit from mnemonic training and thus suggests different avenues from which to approach this training.

The APOE epsilon4 allele is associated with decline on delayed recall performance in community-dwelling older adults.

OBJECTIVE: This study investigated whether the Apolipoprotein (APOE) epsilon4 allele was associated with cognitive decline in community-dwelling older adults. DESIGN: Longitudinal cognitive performance of older adults with the epsilon3/epsilon4 genotype was compared with that of older adults with the epsilon3/epsilon3 genotype. SETTING: Aging Clinical Research Center, Stanford University. PARTICIPANTS: One hundred community-dwelling older adults were recruited from a pool of 531 individuals who had participated in a memory training study 4 to 5 years earlier. These individuals were concerned about their memory functioning and were recruited through newspaper advertisements and contacts with local senior centers. The 100 individuals who agreed to participate in the follow-up investigation were between 59 and 95 years of age. MEASUREMENTS: At both baseline and follow-up, subjects were administered a battery of seven cognitive tests that examined verbal and spatial memory, attention, speed-of-processing, and language abilities. APOE genotype was determined at follow-up. RESULTS: Individuals with the epsilon3/epsilon4 APOE genotype were significantly younger than individuals with the APOE epsilon3/epsilon3 genotype. No significant differences were observed between the two groups on measures of attention, speed-of-processing, vocabulary, immediate verbal memory, and immediate spatial memory. However, those older adults with the epsilon3/epsilon4 genotype exhibited significantly greater decline in performance on delayed recall of verbal material than did those with the epsilon3/epsilon3 APOE genotype. CONCLUSION: These findings are consistent with previous studies, which suggest that the APOE epsilon4 allele predicts decline on measures of delayed recall.

Neutron spectral measurements in an intense photon field associated with a high-energy x-ray radiotherapy machine.

High-energy x-ray radiotherapy machines in the supermegavoltage region generate complex neutron energy spectra which make an exact evaluation of neutron shielding difficult. Fast neutrons resulting from photonuclear reactions in the x-ray target and collimators undergo successive collisions in the surrounding materials and are moderated by varying amounts. In order to examine the neutron radiation exposures quantitatively, the neutron energy spectra have been measured inside and outside the treatment room of a Sagittaire medical linear accelerator (25-MV x rays) located at Yale-New Haven Hospital. The measurements were made using a Bonner spectrometer consisting of 2-, 3-, 5-, 8-, 10- and 12-in.-diameter polyethylene spheres with 6Li and 7Li thermoluminescent dosimeter (TLD) chips at the centers, in addition to bare and cadmium-covered chips. The individual TLD chips were calibrated for neutron and photon response. The spectrometer was calibrated using a known PuBe spectrum Spectrometer measurements were made at Yale Electron Accelerator Laboratory and results compared with a neutron time-of-flight spectrometer and an activation technique. The agreement between the results from these independent methods is found to be good, except for the measurements in the direct photon beam. Quality factors have been inferred for the neutron fields inside and outside the treatment room. Values of the inferred quality factors fall primarily between 4 and 8, depending on location.