Kunihiro Iwamoto

Poor sleep quality impairs cognitive performance in older adults.

The prevalence of insomnia increases with age. Short sleep duration is associated with deficits in cognitive performance. We hypothesized that short sleep duration and sleep quality influence cognitive performance in older adults. The study included 78 adults aged 60 years and over (72.2 ± 5.9 years). Total sleep time and sleep efficiency (total sleep time/time in bed × 100) were calculated using actigraphy. We evaluated cognitive performance with the continuous performance test‐identical pairs and the number‐back test. Sleep apnea was evaluated overnight with a portable home monitoring system. The accuracy of the 0‐back test significantly decreased in participants with total sleep time less than 5 h compared with those with total sleep time greater than 7 h, but there was no significant difference in continuous performance test‐identical pairs between the two groups. Participants with sleep efficiency <85% showed a significant decrease in 0‐ and 1‐back test accuracy compared with those with sleep efficiency ≥85%. There were no significant differences in the accuracy of number‐back tests and continuous performance test‐identical pairs between apnea–hypopnea index ≥15 h−1 and apnea–hypopnea index <15 h−1 groups, or among lowest SpO2 ≥ 90%, lowest 80–90%, and lowest SpO2 < 80% groups. Age, total sleep time and sleep efficiency were significantly correlated with accuracy on the 0‐back test. Age and sleep efficiency were significantly correlated with accuracy on the 1‐back test. Multiple regression analysis revealed that total sleep time was independently correlated with accuracy on the 0‐back test, while age was independently correlated with accuracy on the 1‐back test. Our findings suggest that sleep duration and sleep quality may play a role in cognitive performance in older adults.

Insufficient sleep impairs driving performance and cognitive function

Cumulative sleep deprivation may increase the risk of psychiatric disorders, other disorders, and accidents. We examined the effect of insufficient sleep on cognitive function, driving performance, and cerebral blood flow in 19 healthy adults (mean age 29.2 years). All participants were in bed for 8h (sufficient sleep), and for <4h (insufficient sleep). The oxyhaemoglobin (oxyHb) level by a word fluency task was measured with a near-infrared spectroscopy recorder on the morning following sufficient and insufficient sleep periods. Wisconsin card sorting test, continuous performance test, N-back test, and driving performance were evaluated on the same days. The peak oxyHb level was significantly lower, in the left and right frontal lobes after insufficient sleep than after sufficient sleep (left: 0.25+/-0.13 vs. 0.74+/-0.33 mmol, P<0.001; right: 0.25+/-0.09 vs. 0.69+/-0.44 mmol, P<0.01). The percentage of correct responses on CPT after insufficient sleep was significantly lower than that after sufficient sleep (96.1+/-4.5 vs. 86.6+/-9.8%, P<0.05). The brake reaction time in a harsh-braking test was significantly longer after insufficient sleep than after sufficient sleep (546.2+/-23.0 vs. 478.0+/-51.2 ms, P<0.05). Whereas there were no significant correlations between decrease in oxyHb and the changes of cognitive function or driving performance between insufficient sleep and sufficient sleep. One night of insufficient sleep affects daytime cognitive function and driving performance and this was accompanied by the changes of cortical oxygenation response.

The effects of acute treatment with paroxetine, amitriptyline, and placebo on driving performance and cognitive function in healthy Japanese subjects: a double-blind crossover trial.

To assess the effects of antidepressants on driving performance from a different methodological viewpoint in light of the recent traffic accidents.

White matter microstructure of the cingulum and cerebellar peduncle is related to sustained attention and working memory: a diffusion tensor imaging study.

The non-invasive imaging technique of diffusion tensor imaging (DTI) has been used to investigate the microstructural properties of white matter (WM). The present study investigated whether individual differences in the WM structure of normal subjects as measured by fractional anisotropy (FA) values correlate with cognitive performance in terms of sustained attention and working memory. Subjects underwent DTI and performed the Continuous Performance Test (CPT) and N-back task. FA values throughout the brain were correlated with behavioral performance on a voxel-by-voxel basis to investigate relationships between WM microstructure and cognitive function. The discriminability index of CPT correlated positively with FA of the right cingulum. Accuracy of the 2-back task correlated positively with FA in bilateral cerebellar peduncles. WM microstructure of the right cingulum and bilateral cerebellar peduncles appears related to cognitive function such as sustained attention and working memory in the human brain.

The Effects of Acute Treatment with Tandospirone, Diazepam, and Placebo on Driving Performance and Cognitive Function in Healthy Volunteers

To assess the effects of two anxiolytics, diazepam and tandospirone, on driving performance from methodological viewpoints taking frequent rear‐end collisions into account.

Effects of Mild Cognitive Impairment on Driving Performance in Older Drivers

older adult goes back to the concept of frailty. The greater the severity of the infection, the greater the risk of functional decline, but it can also be inferred that the greater the functional decline the greater the frailty (functional status can be evaluated as a risk factor for infectious disease or as an outcome of interest after specific interventions using well-validated instruments). When an acute disease such as infection produces a functional impairment, this condition becomes an index of outcome and should be detected to predict poor clinical course.

Slower Adaptation to Driving Simulator and Simulator Sickness in Older Adults

Background and aims: Methods of assessing driving abilities in the elderly are urgently needed. Although the driving simulator (DS) appears to be a safe and cost-effective method of objectively evaluating driving performance, it may pose adaptation problems for elderly adults. In this study, we examined age-related adaptation deficits on the DS. Methods: Healthy young adults (n=15) and healthy elderly persons (n=17) completed some neuropsychological tests, and then performed a road-tracking task with the DS, which was repeated four times (Trials 1–4). Results: After simulated driving in DS, simulator sickness (SS) was observed in 18.8% of participants. The frequency of SS was 29.4% in elderly adults and 6.7% in young adults, and 17.6% of the elderly participants dropped out of the experiment. Performance on the Necker cube copying task was significantly correlated with the onset of SS. Driving performance also showed a significant interaction between group and trial, for both driving accuracy and vehicle speed. In addition, the performance of elderly adults significantly improved between trials 1 and 4, reaching a plateau in trial 4, whereas that of young adults did not change across trials. Conclusion: This study provides preliminary evidence of slower adaptation to a DS-based driving task by older adults, which was associated with cognitive aging. Age affected driving accuracy and velocity when a road-tracking task was simply repeated. It is concluded that the capacity of elderly people to adapt to DS environments should be taken into consideration when evaluating their performance on DS tasks.

Effects of repeated dosing with mirtazapine, trazodone, or placebo on driving performance and cognitive function in healthy volunteers

This study aimed to evaluate the effects of repeated treatments with the sedative antidepressants mirtazapine and trazodone on driving performance and cognitive function.

Plasma Amitriptyline Level After Acute Administration, and Driving Performance in Healthy Volunteers

Aims:  Amitriptyline triggers the impairment of cognitive and motor functions and has been confirmed to have harmful effects on driving performance. Although interindividual differences in plasma concentration may cause variations in driving performance, the relationship between plasma amitriptyline concentration and its effect on driving performance has not been completely elucidated. Thus, the aim of the present study was to assess the influence of individual pharmacokinetic differences on driving performance and cognitive functions.

Blonanserin Ameliorates Phencyclidine-Induced Visual-Recognition Memory Deficits: the Complex Mechanism of Blonanserin Action Involving D3-5-HT2A and D1-NMDA Receptors in the mPFC

Blonanserin differs from currently used serotonin 5-HT2A/dopamine-D2 receptor antagonists in that it exhibits higher affinity for dopamine-D2/3 receptors than for serotonin 5-HT2A receptors. We investigated the involvement of dopamine-D3 receptors in the effects of blonanserin on cognitive impairment in an animal model of schizophrenia. We also sought to elucidate the molecular mechanism underlying this involvement. Blonanserin, as well as olanzapine, significantly ameliorated phencyclidine (PCP)-induced impairment of visual-recognition memory, as demonstrated by the novel-object recognition test (NORT) and increased extracellular dopamine levels in the medial prefrontal cortex (mPFC). With blonanserin, both of these effects were antagonized by DOI (a serotonin 5-HT2A receptor agonist) and 7-OH-DPAT (a dopamine-D3 receptor agonist), whereas the effects of olanzapine were antagonized by DOI but not by 7-OH-DPAT. The ameliorating effect was also antagonized by SCH23390 (a dopamine-D1 receptor antagonist) and H-89 (a protein kinase A (PKA) inhibitor). Blonanserin significantly remediated the decrease in phosphorylation levels of PKA at Thr197 and of NR1 (an essential subunit of N-methyl-D-aspartate (NMDA) receptors) at Ser897 by PKA in the mPFC after a NORT training session in the PCP-administered mice. There were no differences in the levels of NR1 phosphorylated at Ser896 by PKC in any group. These results suggest that the ameliorating effect of blonanserin on PCP-induced cognitive impairment is associated with indirect functional stimulation of the dopamine-D1-PKA-NMDA receptor pathway following augmentation of dopaminergic neurotransmission due to inhibition of both dopamine-D3 and serotonin 5-HT2A receptors in the mPFC.