Naoko Kawano

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.

Does cerebral small vessel disease predict future decline of cognitive function in elderly people with type 2 diabetes

AIMS We conducted a 3-year longitudinal study concerning an association between cognitive function and cerebral small vessel disease (SVD) seen on magnetic resonance imaging (MRI) in elderly type 2 diabetic patients. METHODS Four cognitive function tests--MMSE, word recall, Digit Symbol Substitution (DSS), and Stroop Color Word (Stroop)--were performed in 67 diabetic patients twice in 2006 and 2009. SVD was diagnosed as silent brain infarct (SBI) and white matter lesions (WMLs) according to MRI. RESULTS Number of SBI was significantly correlated with a decline in DSS and Stroop tests, while WMLs grade was only associated with it in DSS tests after adjustment for age, gender, education years, the presence of hypertension and dyslipidemia, and smoking. Severity of SVD at baseline was stronger associated with cognitive function after the 3-year follow-up than at baseline. WMLs progression was associated with more rapid decline of DSS tests compared to a group without progression. CONCLUSIONS SVD seen on MRI is a good marker for predicting future cognitive decline, and monitoring of treatment through the use of such markers is expected to maintain a good quality of life for elderly diabetic patients.

Common variants in MAGI2 gene are associated with increased risk for cognitive impairment in schizophrenic patients.

Schizophrenia is a complex psychiatric disorder characterized by positive symptoms, negative symptoms, and cognitive impairment. MAGI2, a relatively large gene (∼1.5 Mbps) that maps to chromosome 7q21, is involved in recruitment of neurotransmitter receptors such as AMPA- and NMDA-type glutamate receptors. A genetic association study designed to evaluate the association between MAGI2 and cognitive performance or schizophrenia has not been conducted. In this case-control study, we examined the relationship of single nucleotide polymorphism (SNP) variations in MAGI2 and risk for schizophrenia in a large Japanese sample and explored the potential relationships between variations in MAGI2 and aspects of human cognitive function related to glutamate activity. Based on the result of first schizophrenia genome-wide association study in a Japanese population (JGWAS), we selected four independent SNPs and performed an association study using a large independent Japanese sample set (cases 1624, controls 1621). Wisconsin Card Sorting Test (WCST) was used to evaluate executive function in 114 cases and 91 controls. We found suggestive evidence for genetic association of common SNPs within MAGI2 locus and schizophrenia in Japanese population. Furthermore in terms of association between MAGI2 and cognitive performance, we observed that genotype effect of rs2190665 on WCST score was significant (p = 0.034) and rs4729938 trended toward significance (p = 0.08). In conclusion, although we could not detect strong genetic evidence for association of common variants in MAGI2 and increased schizophrenia risk in a Japanese population, these SNPs may increase risk of cognitive impairment in schizophrenic patients.

Association of chronic kidney disease and cerebral small vessel disease with cognitive impairment in elderly patients with type 2 diabetes.

Background/Aims: In recent years, the relationship between chronic kidney disease (CKD) and cognitive impairment has been attracting attention. Cerebral small vessel disease (SVD) is also associated with an increased risk of cognitive impairment. However, it is still unknown whether CKD markers are associated with cognitive impairment independently of SVD in elderly diabetic patients. Methods: Seventy-nine type 2 diabetic patients (mean age, 76.0 years) were enrolled in the present study. CKD was defined as the presence of albuminuria and/or a low estimated glomerular filtration rate (eGFR <60 ml/min/1.73 m2). SVD was evaluated by the presence and severity of silent brain infarcts (SBIs) and white matter lesions (WMLs) on brain magnetic resonance imaging. Neuropsychological tests were assessed using four validated cognitive instruments. Results: In multiple linear regression analyses, albuminuria was associated with worse modified Stroop Color Word scores (β = 0.284, p = 0.017) and low eGFR was associated with reduced Digit Symbol Substitution scores (β = -0.224, p = 0.026) after adjustment for age, sex, education years, diabetes duration, hypertension, multiple SBIs, and advanced WMLs. In contrast, there were no significant associations between CKD markers and Mini-Mental State Examination or Word Recall scores. Conclusion: Our findings suggest that albuminuria and low eGFR are associated with frontal lobe dysfunction independently of SVD in elderly type 2 diabetic patients.

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.

Factors Associated with Cognitive Decline in Elderly Diabetics

Background/Aims: Although recent evidence has indicated that type 2 diabetes mellitus (T2DM) in the elderly is a risk factor for cognitive dysfunction or dementia, few studies have prospectively observed this potential cognitive decline. In the current study, we performed cognitive assessments at baseline and after 3 years in the same patient group in an attempt to reveal the contributions of diabetes-related factors to the increased decline in cognitive function in elderly patients with T2DM. Methods: We recruited 55 consecutive T2DM patients with a Mini-Mental State Examination (MMSE) score ≧24 from the Diabetic Center at the Chubu Rosai Hospital. These patients ranged in age from 65 to 85 years. Cognitive and clinical assessments, including brain MRI, were performed at baseline and at the 3-year follow-up. Results: The higher plasma insulin and HbA1c levels observed at baseline were significantly associated with a worse cognitive performance at baseline and a more neurocognitive decline at the follow-up visit. Conclusion: The current prospective study suggests that higher insulin and glycohemoglobin levels may be associated with diabetes-related cognitive dysfunction.

Estimated cognitive decline in patients with schizophrenia: A multicenter study

Studies have reported that cognitive decline occurs after the onset of schizophrenia despite heterogeneity in cognitive function among patients. The aim of this study was to investigate the degree of estimated cognitive decline in patients with schizophrenia by comparing estimated premorbid intellectual functioning and current intellectual functioning.

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.

Factors associated with cognitive decline in older adults with type 2 diabetes mellitus during a 6-year observation.

Type 2 diabetes mellitus (T2DM) is a risk for cognitive decline in older adults. The current study was carried out to determine the factors associated with cognitive decline.