Memory and attention test performance of young and elderly subjects after retest practice

Effects of blood glucose levels on resting-state EEG and attention in healthy volunteers

PURPOSE

Although glucose is the primary source of energy for the human brain, only a few studies have quantitatively evaluated the effects of glucose supply in healthy fasting subjects. Thus, this study used an EEG power spectral analysis to investigate whether alterations in EEG are associated with changes in blood glucose levels in healthy fasting subjects.

METHODS

This study included 24 healthy volunteers who underwent resting-state EEG and completed two attention examinations following a fasting period of at least 8 hours. The same tests were repeated after the participants ingested a glucose-rich drink.

RESULTS

After consumption of the glucose-rich drink, significant increases in low alpha (8-10 Hz) and theta (4-8 Hz) power were observed in the whole brain and were especially prominent in the frontal and parieto-occipital regions. The participants performed better on the attention tests after than before the intake of glucose, but regional EEG changes were not correlated with this attentional enhancement.

CONCLUSIONS

The present study demonstrated that recovery from low levels of blood glucose following a prolonged fasting period was associated with increased power in the theta and low alpha bands on a resting-state EEG and that this recovery was accompanied by improved attentional performance.

Preserving cognition through an integrated cognitive stimulation and training program

BACKGROUND

Cognitive decline leads to disability and increased health care expenditures.

METHODS

Effectiveness of an intervention to stimulate multiple cognitive domains was determined using a format combining traditional and computer-based activities (Integrated Cognitive Stimulation and Training Program), 45 minutes a day, 2 days a week, for 6 weeks. Nonimpaired, mildly, and moderately-impaired participants > age 65 (n = 32) were randomly allocated into a control or experimental group. Using a repeated measures design participants were tested again postintervention and at 8 weeks follow-up.

RESULTS

Statistically significant improvement on Dementia Rating Scale scores occurred for mildly and moderately impaired treatment participants (n = 15). Statistical significance was demonstrated on subscales of the WMS-III: Logical Memory I and Logical Memory II.

CONCLUSION

Blending computer-based with traditional cognitive stimulation activities shows promise in preserving cognitive function in elders. Future studies to explore efficacy in larger, more diverse samples are needed.

Basic forms of cognitive plasticity extended into the oldest-old: Retest learning, age, and cognitive functioning

To address the question of whether cognitive plasticity varies by age and level of cognitive functioning in the older population, the authors used a self-guided retest paradigm to assess the basic forms of plasticity of 34 young-olds (M=74.4 years, range=70-79) and 34 oldest-olds (M=84.0 years, range=80-91), with half in each age group screened for high or low (midrange) level of cognitive functioning. As a whole, members of the sample represent about the upper two thirds of their age cohorts. Results show persistent, though age-reduced, learning in all samples and across all tests. However, age is not differentially "kinder" to the more able with respect to the age-graded decline in learning.

Response selection and execution in patients with Parkinson's disease

Different studies report diverse, sometimes conflicting findings, regarding the ability of Parkinson's disease (PD) patients to benefit from advanced cuing in choice reaction time (RT). Thus, conclusions about the changed state of underlying processes such as set formation, motor programming and motor initiation are not certain. In the present study, visual choice RT testing that utilized brief (100 ms) color signals (red/blue), was followed by auditory choice reaction time (CRT) testing with brief (100 ms) low/high pitch sound stimuli. Response consisted of either index or middle finger flexion. The signals were then combined so that the color stimuli cued the sound stimuli with an 800-ms interstimuli interval. Cuing validity was reduced from 100% during training to 76% during final testing. In addition, the same sound stimuli were presented randomly, without visual cuing, in which case response should have been suppressed. Tested subjects include 19 moderate PD patients, 21 elderly controls and 20 young controls. The patients did not differ from the controls in error rate but were slower to respond, except under 100% congruent cuing, indicating that their extended RT in CRT results from slowed stimulus-response linking and not from impaired motor initiation/execution. In the final condition patients showed no perseverance and demonstrated normal speed of set shifting in incongruent trials.

Aging and cognition

A substantial portion of elderly people experience declines in mental capacities. While these changes are often attributable to serious dementing illnesses such as Alzheimer's disease, a surprising number result from apparently normal aging processes. The effects of senescence on cognition may be indirect (i.e., gait instability leading to falling and subsequent head trauma); however, they may have a more direct and subtle impact on the brain. The evidence available to date suggests that only a limited range of cognitive domains are susceptible to these aging effects. Perhaps the most important are short-term memory functions. The specific character of these and other age-related cognitive deficits are reviewed.