Development of an assessment scale for engagement in activities for patients with moderate to severe dementia

BACKGROUND

Various types of therapy, including occupational therapy, are utilised for the treatment of moderate to severe dementia. In order to determine the optimal rehabilitation strategy for such patients and examine the treatment efficacy, an assessment scale for engagement in various group activities that can be easily applied in clinical situations is required. We herein report the development of the Assessment Scale for Engagement in Activities (ASEA) and its clinical utility.

METHODS

The ASEA was developed by nine occupational therapists and a psychiatrist with experience in developing measures for dementia, in accordance with the COSMIN (COnsensus-based Standards for the selection of health status Measurement INstruments) checklist. This assessment comprises 10 items covering four domains: Engagement in the Activity, Interaction, Arousal, and Affect. Participants with moderate to severe dementia who resided in a psychiatric acute phase hospital in Japan were assessed in terms of engagement in activities using the ASEA and Todai-shiki Observational Rating Scale (TORS), and in terms of cognitive function using the Mini-Mental State Examination (MMSE). We examined the internal consistency, inter- and intra-rater reliability, content validity, and concurrent validity of the ASEA.

RESULTS

Cronbach's alpha of the ASEA was 0.889. The overall inter-rater reliability was 0.937 (Spearman rank correlation, P < 0.001), and the intraclass correlation (ICC) for each item was 0.490-0.965 (P < 0.018-0.001). The overall test-retest reliability was 0.778 (Spearman's rank correlation, P < 0.001), and the ICC for each item was 0.498-0.863 (P < 0.023-0.001). The test-retest correlations were significant for almost all items, aside from 'Interaction with others' (P = 0.051). The concurrent validity, examined using the TORS and MMSE, was 0.920 and 0.304 (Spearman's rank correlation, P < 0.001-0.006).

CONCLUSIONS

The ASEA has confirmed reliability and validity, aside from 'Interaction with others' regarding test-retest reliability. Generally, this assessment tool has clinical utility and allows the evaluation of activity engagement among patients with moderate to severe dementia.

Association of Oral Hypofunction with Frailty, Sarcopenia, and Mild Cognitive Impairment: A Cross-Sectional Study of Community-Dwelling Japanese Older Adults

Oral hypofunction is a new concept that addresses the oral function of older adults. Few studies have investigated the relationship between oral hypofunction and general health conditions such as frailty, sarcopenia, and mild cognitive impairment. This paper explores these relationships in a large-scale, cross-sectional cohort study. The relationships of oral hypofunction with frailty, sarcopenia, and mild cognitive impairment were examined using data from 832 individuals who participated in the 2018 health survey of the residents of Tarumizu City, Kagoshima Prefecture, Japan. Individuals with frailty, sarcopenia, and mild cognitive impairment had significantly higher rates of oral hypofunction. Frailty was independently associated with deterioration of the swallowing function (odds ratio 2.56; 95% confidence interval, 1.26-5.20), and mild cognitive impairment was independently associated with reduced occlusal force (odds ratio 1.48; 95% confidence interval, 1.05-2.08) and decreased tongue pressure (odds ratio 1.77; 95% confidence interval, 1.28-2.43). There was no independent association found between sarcopenia and oral function. In conclusion, early intervention for related factors such as deterioration of the swallowing function in frailty, reduced occlusal force, and decreased tongue pressure in mild cognitive impairment could lead to the prevention of general hypofunction in older adults.

Usefulness of navigation application for outdoor mobility guides in community-dwelling older adults: a preliminary study

PURPOSE

This study aimed to examine a mobile device navigation application's (apps) usefulness as a guide based on the required time and accuracy of moving to a destination for community-dwelling older adults.

METHODS

Twelve older adults, aged ≥65 years (mean age 77.0 ± 8.0, 62% female) who used the day-care centre for older adults, based on the long-term care insurance system in Kagoshima Prefecture, participated in this study. Study participants performed a Route Navigation Task (RNT), which is a simple real-world navigation test based on the actual living environment, after a brief assessment of physical function, cognitive function, and daily living routine. RNT required that participants arrive at a destination for the shortest time, under three tasks: map-, app-, and photo-language. The order of implementation of each task, determined by one of the tasks, was randomized, with a span of a minimum 1 month between tasks.

RESULTS

The app-task resulted in a significantly shorter amount of travel time than did the other tasks (p < 0.05). The factors considerably correlating with travel time in the app-task were walking speed, mobile device proficiency, years of mobile device use, and higher-order activities of daily living.

CONCLUSION

Our findings suggested the possibility that the navigation app was useful as efficient outdoor mobility support, and healthcare providers should encourage the use of mobile devices for improving the active lifestyle of the community-dwelling older adults.IMPLICATIONS FOR REHABILITATIONThe navigation apps in mobile devices are expected to be useful for community-dwelling older adults.We examined the effect of navigation app use on path execution using three tasks in RNT and what factors are associated with the ability of route navigation.A significant reduction in travel time when RNT was performed using a navigation app compared to the other two tasks (map, photo-language).Regardless of cognitive function, mobile device proficiency, and mobile device usage were associated with navigation app use.This study suggests the usefulness of a navigation application in providing route assistance to community-dwelling older adults.

Hearing impairment is associated with cognitive function in community-dwelling older adults: A cross-sectional study

BACKGROUND

Hearing impairment (HI) is associated with dementia. However, the cognitive screening tasks effective in older community dwellers presenting with HI are unclear.

METHODS

We retrospectively and cross-sectionally investigated the associations between HI and cognitive function assessed with screening tasks using data from two healthcare check-up programs for community dwellers ≥65 years old in 2018. We examined demographics, risk factors, cognitive function, hearing condition, lifestyles, and self-care levels. Cognitive function was assessed using the clock drawing task and the delayed three words recall task. Hearing condition was assessed using questionnaires on the use of hearing aids and HI during conversation situations. Multivariate analysis was used to identify independent associations between HI and cognitive assessment tasks.

RESULTS

We analyzed 1602 eligible participants (61.9% women; 74.3 ± 6.5 years old). Hearing aid users (n = 90) were older (80 vs. 73 years, respectively; p < 0.001) and less likely to draw the clock correctly (71.1% vs. 80.1% years, respectively; p = 0.044) than non-hearing aid users. Multivariate logistic regression analysis showed that HI was associated with inability to draw the clock correctly (odds ratio 1.60, 95% confidence interval 1.12-2.26; p = 0.011), independent of age, living alone, memory impairment, and impaired self-care levels.

CONCLUSION

Hearing impairment is independently associated with cognitive decline assessed by the clock drawing task. The clock drawing task may be useful for identifying an increased risk of dementia in older subjects presenting with HI.

Relationship Between Attention Bias and Psychological Index in Individuals With Chronic Low Back Pain: A Preliminary Event-Related Potential Study

Introduction: Attention bias towards pain-related information exists in patients with chronic pain, and recently, attention bias modification (ABM) training has been administered to patients with chronic pain. In this study, we conducted an attention bias modification task in conjunction with event-related potential measurements for individuals with chronic low back pain (LBP) and investigated the relationship between attention bias and psychological assessment.

Methods: Eleven women and two men with chronic LBP participated in the study.

Results: The Japanese version of the STarT Back Screening Tool (J-SBST) total score was significantly correlated with the N1 amplitude of Cz. The J-SBST psychological score was significantly correlated with the N1 amplitude of Cz and with reaction time (RT). The Japanese version of the Pain Catastrophizing Scale (PCS) and Japanese version of the Beck Depression Inventory-Second Edition (BDI-II) scores were significantly correlated with the P2 amplitude at Fz (only PCS), Cz, and Pz.

Conclusions: Our findings suggest that J-SBST, which provides a comprehensive evaluation of psychological factors, PCN with measuring of catastrophizing in the context of actual or anticipated pain, and BDI-II, can likely help identify chronic LBP patients with attention bias. For chronic LBP patients who are classified according to J-SBST or PCN pain-related outcome improvement with ABM training can be expected.

Association between Daily Activities and Behavioral and Psychological Symptoms of Dementia in Community-Dwelling Older Adults with Memory Complaints by Their Families

It is important and useful to consider information provided by family members about individuals with memory complaints' instrumental activities of daily living (IADL). The purpose of this study was to clarify the characteristics and relevance of individuals with memory complaints' IADL and behavioral and psychological symptoms of dementia (BPSD) assessed from the perspective of the family members using the Process Analysis of Daily Activity for Dementia and short version Dementia Behavior Disturbance scale. A self-administered questionnaire was sent to 2000 randomly selected members of Consumer's Co-operative Kagoshima, and 621 responded. Of the returned responses, there were 159 participants who answered about individuals with memory complaints. The stepwise multiple regression analysis was used to examine the association between IADL and BPSD. The result showed that many IADL of the individuals with memory complaints were associated with BPSD of apathy, nocturnal wakefulness, and unwarranted accusations, adjusted for age, gender, and the observation list for early signs of dementia. In addition, each IADL was associated with BPSD of apathy, nocturnal wakefulness, and dresses inappropriately. Modifying lifestyle early on when families recognize these changes may help maintain and improve the long-term quality of life of the individuals with memory complaints and their family.

Causes of changes in basic activities of daily living in older adults with long-term care needs

OBJECTIVE

To elucidate basic activities of daily living (BADL) changes, and the causes, in older adults with long-term care needs.

METHODS

This retrospective study utilised long-term care insurance (LTCI) certification survey data from 2010 to 2017 in City A.

RESULTS

In decreasing likelihood of requiring assistance, BADL items were grooming, bathing, getting dressed/undressed, mobility, toilet hygiene, functional mobility and self-feeding. Cox proportional hazard regression indicated that age correlated with need for assistance for all BADL items. Male sex corresponded to needing assistance with BADL items other than grooming and functional mobility. Shared living corresponded to needing assistance with BADL items other than grooming and bathing. Visual acuity corresponded to needing assistance with grooming.

CONCLUSION

The most significant result was using survival curves to visualise the changes in BADL items of older adults with LTCI. These findings could help develop rehabilitation programs to prevent the need for BADL assistance in older adults.

Relationship between Performance on the Mini-Mental State Examination Sub-Items and Activities of Daily Living in Patients with Alzheimer's Disease

Mini-mental state examination (MMSE) subitems provide useful information about the cognitive status of patients with Alzheimer's disease (AD). If the relationship between MMSE subitems and activities of daily living (ADL) can be shown, the performance of sub-items can predict ADL status and may provide useful information for early ADL intervention. Therefore, the purpose of this study was to investigate the relationship between MMSE subitem scores and ADL. The study sample consisted of 718 patients with AD. Logistic regression analysis using the Physical Self-maintenance Scale (PSMS) and Lawton's Instrumental ADL (L-IADL) was performed with each of the subitems as the dependent variables and the MMSE subitem as the independent variable. As a result, the subitems of MMSE, which are strongly related to each item in PSMS differed (e.g., toilet: registration odds ratio 3.00, grooming: naming 3.66). In the case of L-IADL, most items were strongly associated with "writing" (e.g., shopping: odds ratio 4.29, laundry 3.83). In clinical practice, we often focus only on the total MMSE score in patients with AD. However, the relationship between each MMSE subitem and ADL suggested in this study may be useful information that can be linked to ADL care from the performance of the MMSE subitem.

Impact of sensory impairments on dementia incidence and symptoms among Japanese older adults

BACKGROUND

Dementia and behavioural and psychological symptoms of dementia affect older adults' care-need levels. With aging comes an increase in the incidence of sensory impairments, which promotes the development of dementia. We investigated the association between sensory impairments - visual impairment (VI), hearing impairment (HI), and dual sensory impairment (DSI), the behavioural and psychological symptoms of dementia, and dementia incidence.

METHODS

This was a retrospective study that used Japanese long-term care insurance certification data from 2010 to 2017 of City A. The 2190 older adults who did not have dementia in 2010 were classified into four impairment categories: VI, HI, DSI, and no sensory impairment. The incidence of dementia was examined using Kaplan-Meier survival analysis and log-rank testing. Cox proportional hazards analysis was used to investigate the risk of developing dementia associated with sensory impairments, compared to the risk for no sensory impairment. Pearson's χ² tests were used to compare the prevalence of behavioural and psychological symptoms of dementia among the four groups.

RESULTS

HI and DSI were associated with a higher cumulative dementia incidence compared to no sensory impairment (log-rank χ² = 10.42; P  < 0.001, and log-rank χ² = 39.92; P  < 0.001, respectively), and DSI showed higher cumulative dementia incidence than HI (log-rank χ² = 11.37; P  = 0.001). Cox proportional hazards analysis showed that DSI is the greatest risk factor for developing dementia among sensory impairments (hazard ratio, 1.45; 95% CI, 1.22-1.71; P < 0.001). Older adults with VI had a significantly higher prevalence of day-night reversal than the other groups.

CONCLUSIONS

Our results indicate that older adults with sensory impairments have a high incidence of dementia, with DSI presenting the greatest risk. Older adults with VI were found to be more likely to have day-night reversal symptoms when dementia occurs.

Age-Related Changes in Instrumental and Basic Activities of Daily Living Impairment in Older Adults with Very Mild Alzheimer's Disease

Background/Aims

Age-related changes in impairments in activities of daily living (ADL) in older adults with very mild Alzheimer's disease (vmAD) have been scarcely explored. We clarified the characteristics of ADL impairment and examined how ADL impairments differed by age in such patients compared with community-dwelling cognitively normal older adults.

Methods

The participants were 107 older adults with vmAD (Mini-Mental State Examination [MMSE] score ≥24), all of whom were first-visit outpatients at the Dementia Clinic of the Department of Neuropsychiatry, Kumamoto University Hospital. The controls were 682 community-dwelling older adults who participated in the 3rd Nakayama Study with MMSE score ≥24. We examined the association of instrumental and basic ADL (IADL and BADL, respectively) independence with the odds of vmAD using multiple logistic regression analysis and determined differences in ADL impairment by age using age- and sex-matched analysis.

Results

Impairments in handling finances (OR 57.08), managing medication (OR 5.13), and dressing (OR 3.35; BADL) were associated with greater odds of vmAD. Among those aged 65 years and above, there were fewer patients with vmAD than healthy controls who could independently handle finances and medication. Among patients with vmAD, the percentages of those who could independently manage shopping, food preparation, and housekeeping only decreased after age 74. Age-related decreases in independence were observed in few BADL items; these, however, were temporary.

Conclusions

Patients with vmAD show significantly decreased IADL independence from early old age.

Associations between Depressive Symptoms and Satisfaction with Meaningful Activities in Community-Dwelling Japanese Older Adults

The aim of this cross-sectional study was to investigate relationships between individuals' ratings of satisfaction and performance of activities that they found meaningful and depressive symptoms. Data was obtained from 806 older adults (mean age 74.9 ± 6.3 years, women = 63.0%) who participated in a community-based health check survey (Tarumizu Study 2018). Participants selected meaningful activities from 95 activities using the Aid for Decision-Making in Occupation Choice and evaluated their satisfaction and performance. Depressive symptoms were assessed using the 15-item Geriatric Depression Scale (GDS-15) and defined by a GDS-15 score of ≥5. Non-linear logistic regression analyses were used separately by gender to examine the association between satisfaction and performance of meaningful activities and depressive symptoms. The prevalence of depressive symptoms was 15.8%. We found no significant difference between meaningful activity choice between older adults with depressive symptoms and those without, in both men and women. After adjusting for potential covariates, satisfaction was associated with depressive symptoms in both men (OR 0.52, 95% CI 0.35-0.77) and women (OR 0.67, 95% CI 0.49-0.91), but performance was limited in women (OR 0.87, 95% CI 0.77-0.99). Our findings suggest that depressive symptoms are associated with satisfaction in meaningful activities regardless of activity categories.

Instrumental Activities of Daily Living: The Processes Involved in and Performance of These Activities by Japanese Community-Dwelling Older Adults with Subjective Memory Complaints

Subjective memory complaints (SMCs) may predict the onset of dementia. The purpose of this study was to clarify characteristics of performance of activities of daily living (ADL) for older adults with SMCs and to offer support options that enable them to maintain their community-based lifestyle. A self-administered questionnaire was sent to 2000 randomly selected members of CO-OP Kagoshima, and 621 responded. 270 responders answered all questions were categorized into SMC (+) group and SMC (−) group (n = 133). Participants were evaluated the Process Analysis of Daily Activity for Dementia. A 2-sample t-test or the Chi-square test were used to compare the averages of continuous variables or the proportions of categorical variables. The results showed the SMC (+) group ranked significantly lower in ability to use the telephone, shop, cook, do housekeeping, manage finances, and manage medications compared with the SMC (−) group. In addition, the SMC (+) group was significantly less independent than the SMC (−) group in many processes requiring the use of tools, operation of machines, management of goods, selection of tools, and monitoring. To enable continued independence of older adults’ experiencing SMCs, it may be important to analyze their performance of ADL and to develop plans for supporting their strengths.

Effect of occupation-based interventions in patients with haematopoietic malignancies undergoing chemotherapy: A pilot randomised controlled trial

BACKGROUND/OBJECTIVE

Chemotherapy for cancer negatively affects activities of daily living and quality of life. This study aimed to validate and compare the efficacy of two different interventions in patients with haematopoietic malignancies undergoing chemotherapy: (1) occupation-based interventions, designed using the Aid for Decision-making in Occupation Choice (ADOC) (an iPAD application) and (2) impairment-based interventions. ADOC helps promote decision-making during activities and participation in occupation-based goal setting. The impairment-based intervention group served as the comparison group and underwent impairment-based interventions focusing on dysfunction.

METHODS

In this single-blinded pilot randomised controlled trial, 19 participants received an occupation-based intervention (n = 9) or an impairment-based intervention (n = 10). The treatment period comprised two sessions. Recruitment, compliance and outcome completion rates were calculated for the study. Effect sizes were examined for outcomes regarding physical performance, instrumental activities of daily living and quality of life as evaluated by a blinded assessor.

RESULTS

In this study, 24.8% (28/113) of the eligible patients with haematopoietic malignancies were enrolled, and 67.9% (19/28) of these were retained up to the post-assessment stage. Recruitment (25%) and compliance (68%) rates were satisfactory. The Functional Assessment of Cancer Therapy-General emotional well-being and total scores were significantly higher for the occupation-based intervention group than for the impairment-based intervention group (both p < 0.05; d = 0.54, d = 0.51, respectively). Other outcomes showed no significant differences.

CONCLUSION

Occupation-based interventions designed using the ADOC application were useful for patients with haematopoietic malignancies.

Factors affecting the self-rated health of elderly individuals living alone: a cross-sectional study

Objective

In Japan, the number of elderly individuals living alone is continuing to increase as society ages. Although studies have considered quality of life, life expectancy, and gender differences in elderly individuals living alone, only a few have considered the health and lifestyle of these individuals. Therefore, we aimed to investigate the factors that affect the self-rated health of elderly individuals living alone to understand this group and how best to offer them support.

Results

We include 113 individuals. There was a significant difference (P < 0.05) in some characteristics (e.g., age, chronic illness, frequency of hospital visits in 1 month, and caregivers), activities of daily living (e.g., motor tasks), and instrumental activities of daily living (e.g., household affairs, heavy housework, outdoor household, and outdoor activities).

Effect of mental practice using inverse video of the unaffected upper limb in a subject with chronic hemiparesis after stroke

[Purpose] The aim of this case study was to investigate whether a method of mental practice (MP) using an inverse video of a subject’s unaffected limb to complement the vividness of motor imagery (MI) would be effective for improving affected upper limb function. [Subjects and Methods] The participant was 60-year-old male in the chronic stage of stroke recovery with left sided hemiparesis. The design of the study was AB method of Single-System-Design. He performed the MP as a home program with DVD. The intervention lasted 30 minutes a session, twice a day, 5 times a week, over 6 weeks. The DVD was created using inverse video of his unaffected upper limb. Primary outcome measures were used the Fugl-Meyer Assessment for upper limb (FMA) and the Motor Activity Log (MAL) 3 times each baseline, intervention and follow-up. The subjective vividness of MI was assessed by the Visual Analog Scale (VAS). [Results] FMA and MAL score during intervention was improved significantly comparing to baseline, and maintained in withdrawal. VAS score was improved in withdrawal comparing to baseline. [Conclusion] Results suggested that effect of mental practice for stroke patients increased by vividness of motor imagery was improved by the inverse video.

Monitoring Local Regional Hemodynamic Signal Changes during Motor Execution and Motor Imagery Using Near-Infrared Spectroscopy

The aim of this study was to clarify the topographical localization of motor-related regional hemodynamic signal changes during motor execution (ME) and motor imagery (MI) by using near-infrared spectroscopy (NIRS), as this technique is more clinically expedient than established methods (e.g., fMRI). Twenty right-handed healthy subjects participated in this study. The experimental protocol was a blocked design consisting of 3 cycles of 20 s of task performance and 30 s of rest. The tapping sequence task was performed with their fingers under 4 conditions: ME and MI with the right or left hand. Hemodynamic brain activity was measured with NIRS to monitor changes in oxygenated hemoglobin (oxy-Hb) concentration. Oxy-Hb in the somatosensory motor cortex (SMC) increased significantly only during contralateral ME and showed a significant interaction between task and hand. There was a main effect of hand in the left SMC. Although there were no significant main effects or interactions in the supplemental motor area (SMA) and premotor area (PMA), oxy-Hb increased substantially under all conditions. These results clarified the topographical localization by motor-related regional hemodynamic signal changes during ME and MI by using NIRS.

Changes in Cerebral Hemodynamics during Complex Motor Learning by Character Entry into Touch-Screen Terminals

Introduction

Studies of cerebral hemodynamics during motor learning have mostly focused on neurorehabilitation interventions and their effectiveness. However, only a few imaging studies of motor learning and the underlying complex cognitive processes have been performed.

Methods

We measured cerebral hemodynamics using near-infrared spectroscopy (NIRS) in relation to acquisition patterns of motor skills in healthy subjects using character entry into a touch-screen terminal. Twenty healthy, right-handed subjects who had no previous experience with character entry using a touch-screen terminal participated in this study. They were asked to enter the characters of a randomly formed Japanese syllabary into the touch-screen terminal. All subjects performed the task with their right thumb for 15 s alternating with 25 s of rest for 30 repetitions. Performance was calculated by subtracting the number of incorrect answers from the number of correct answers, and gains in motor skills were evaluated according to the changes in performance across cycles. Behavioral and oxygenated hemoglobin concentration changes across task cycles were analyzed using Spearman’s rank correlations.

Results

Performance correlated positively with task cycle, thus confirming motor learning. Hemodynamic activation over the left sensorimotor cortex (SMC) showed a positive correlation with task cycle, whereas activations over the right prefrontal cortex (PFC) and supplementary motor area (SMA) showed negative correlations.

Conclusions

We suggest that increases in finger momentum with motor learning are reflected in the activity of the left SMC. We further speculate that the right PFC and SMA were activated during the early phases of motor learning, and that this activity was attenuated with learning progress.

Excitability of the primary motor cortex increases more strongly with slow- than with normal-speed presentation of actions

Introduction

The aim of the present study was to investigate how the speed of observed action affects the excitability of the primary motor cortex (M1), as assessed by the size of motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS).

Methods

Eighteen healthy subjects watched a video clip of a person catching a ball, played at three different speeds (normal-, half-, and quarter-speed). MEPs were induced by TMS when the model's hand had opened to the widest extent just before catching the ball (“open”) and when the model had just caught the ball (“catch”). These two events were locked to specific frames of the video clip (“phases”), rather than occurring at specific absolute times, so that they could easily be compared across different speeds. MEPs were recorded from the thenar (TH) and abductor digiti minimi (ADM) muscles of the right hand.

Results

The MEP amplitudes were higher when the subjects watched the video clip at low speed than when they watched the clip at normal speed. A repeated-measures ANOVA, with the factor VIDEO-SPEED, showed significant main effects. Bonferroni's post hoc test showed that the following MEP amplitude differences were significant: TH, normal vs. quarter; ADM, normal vs. half; and ADM, normal vs. quarter. Paired t-tests showed that the significant MEP amplitude differences between TMS phases under each speed condition were TH, “catch” higher than “open” at quarter speed; ADM, “catch” higher than “open” at half speed.

Conclusions

These results indicate that the excitability of M1 was higher when the observed action was played at low speed. Our findings suggest that the action observation system became more active when the subjects observed the video clip at low speed, because the subjects could then recognize the elements of action and intention in others.

Ameliorative effect of traditional Japanese medicine yokukansan on age-related impairments of working memory and reversal learning in rats

Aging is thought to impair prefrontal cortical (PFC) structure-sensitive cognitive functions and flexibility, such as working memory and reversal learning. A traditional Japanese medicine, yokukansan (YKS), is frequently used to treat age-related neurodegenerative disorders such as Alzheimer's disease in Japan, but its pharmacological properties have not been elucidated. The present study was designed to examine whether YKS improves age-related cognitive deficits using aged rats. YKS was administered to 21-month-old rats for 3 months. The ability to learn initially a reward rule for a T-maze discrimination task (initial learning) was examined in young control (4-month-old), aged control (24-month-old) and YKS-treated aged (24-month-old) rats. Subsequently, working memory and reversal learning were examined in delayed alternation and reversal discrimination T-maze tasks, respectively. Locomotor activity was also measured in new environments. Although performance accuracy in the initial learning procedure did not differ among any experimental groups, accuracy in the delayed alternation task was significantly decreased in aged rats compared to young rats. Aged rats also showed significant decreases in accuracy in the reversal discrimination task. YKS treatment significantly ameliorated the age-related decreases in accuracy in the delayed alternation and reversal discrimination tasks. The ameliorative effects of YKS on impaired delayed alternation performance were reduced by intracranial infusions of a dopamine D1 receptor antagonist, SCH 23390, into the prelimbic cortical region of the PFC, and the YKS effects on impaired reversal learning were done by the infusions into the orbitofrontal cortex (OFC). Locomotor activity did not change in any experimental group. Thus, YKS ameliorated age-related impairments of working memory and reversal learning, which might be mediated by a dopaminergic mechanism in the PFC structure. These investigations provide information important for the treatment of brain dysfunctions in the elderly people.

Orbitofrontal dopaminergic dysfunction causes age-related impairment of reversal learning in rats

Reversal learning is a domain that involves cognitive flexibility and is defined as the ability to rapidly alter established patterns of behavior when confronted with changing circumstances. This function depends critically on the orbitofrontal cortex (OFC) in the prefrontal cortical (PFC) structure, which is among the most sensitive to the influences of aging, and impaired reversal learning is a common functional disturbance of aged brain. The present study was designed to clarify the precisely neurochemical basis of this impaired learning in rats. For this purpose, we first examined reversal learning in young (3-month-old) and aged (24-month-old) rats using a T-maze discrimination task. The ability of aged rats to learn initially a reward rule for a T-maze discrimination task was almost equal to that of young rats, suggesting that simple discrimination ability was normal in aged rats. However, the ability to learn a reversed rule in a subsequent task was markedly impaired in aged rats. In addition, aged rats had reduced dopaminergic transmission concomitant with attenuated tyrosine hydroxylase (TH) activity in the OFC. Moreover, age-related impairment of reversal learning was improved by an intra-OFC infusion of 30 ng, but not 10 ng, of the D1 receptor agonist SKF 81297. Increasing dose of SKF 81297 to 100 ng also improved the impairment, but this effect was weaker than that of 30 ng, indicating that the SKF 81297 response was an inverted "U" pattern. The maximum SKF 81297 response (30 ng) was abolished by the D1 receptor antagonist SCH 23390. Thus, age-related impairment of reversal learning was due to a D1 receptor-mediated hypodopaminergic mechanism in the OFC. This finding provides direct evidence showing the involvement of OFC dopaminergic dysfunction in the development of cognitive inflexibility during the normal aging process.