Measuring impairments in memory and executive function in older people using the Revised Cambridge Cognitive Examination

Impact of Intestinal Microbiota on Cognitive Flexibility by a Novel Touch Screen Operant System Task in Mice

Cognitive flexibility is the ability to rapidly adapt to a constantly changing environment. It is impaired by aging as well as in various neurological diseases, including dementia and mild cognitive impairment. In rodents, although many behavioral test protocols have been reported to assess learning and memory dysfunction, few protocols address cognitive flexibility. In this study, we developed a novel cognitive flexibility test protocol using touch screen operant system. This test comprises a behavioral sequencing task, in which mice are required to discriminate between the “rewarded” and “never-rewarded” spots and shuttle between the two distantly positioned rewarded spots, and serial reversals, in which the diagonal spatial patterns of rewarded and never-rewarded spots were reversely changed repetitively. Using this test protocol, we demonstrated that dysbiosis treated using streptomycin induces a decline in cognitive flexibility, including perseveration and persistence. The relative abundances of Firmicutes and Bacteroides were lower and higher, respectively, in the streptomycin-treated mice with less cognitive flexibility than in the control mice. This is the first report to directly show that intestinal microbiota affects cognitive flexibility.

Age-Related Performance on the Brixton Spatial Anticipation Test in Healthy Child and Adolescent Girls: A Preliminary Evaluation

The Brixton Spatial Anticipation Test assesses individuals' cognitive flexibility in terms of rule detection and attainment. It has been used to assess executive functioning in both clinical and nonclinical adult samples. However, little is currently known about the suitability of this task for younger populations. The current study therefore aimed to provide an initial exploration of this task's suitability for young people. Brixton responses from a healthy sample of children and adolescents were presented to investigate performance in both rule detection and rule attainment, respectively. A convenience sample of 72 female participants (Mage = 14.95 years, SD = 1.53 years, range = 11-17 years; MIQ = 103.76, SD = 10.81) was studied. The sample was divided according to age into four groups (11-12 years, 13-14 years, 15 years, and 16-17 years) to allow for developmental trajectory. No significant age performance differences were found. Small effect sizes between age groups lend support to the null findings. The current study suggests that the Brixton task norms are suitable for use with individuals aged 11 to 17 years old. However, normative work is still needed in this area, incorporating an adult sample for comparison, to comment upon the developmental trajectory specific to this task.

Cognitive Domains and Health-Related Quality of Life in Alzheimer's Disease

OBJECTIVES

The nature of the association between the cognitive decline and quality of life (QoL) during the course of Alzheimer's disease (AD) has not been studied in detail. We designed this study to determine if the association between cognitive domains in AD and health-related quality of life (HRQoL) changed over 18 months.

METHODS

We recruited 80 community-dwelling older adults with mild to moderate AD and 61 healthy elderly controls as well as their next-of-kin. The primary outcome measure was the QoL-AD. Specific cognitive functions were assessed with a broad range of neuropsychological measures, which were later grouped into cognitive domains following factor analyses at the baseline and 18-month assessments. Other explanatory variables included demographics, psychopathology, burden of care, and use of medication.

RESULTS

Self-reported QoL-AD scores were not associated with any of the identified cognitive domains at either assessment. The cognitive domains of people with AD changed between baseline and the 18-month assessment, as did the association of these factors with carer-rated HRQoL. The HRQoL scores assigned by the next-of-kin declined alongside a general measure of cognitive function.

DISCUSSION

These results indicate that HRQoL is not consistently associated with specific cognitive domains in AD and that cognitive-enhancing focused therapies may fail to affect the HRQoL of people with AD.

Covariant perfusion patterns provide clues to the origin of cognitive fluctuations and attentional dysfunction in dementia with Lewy bodies

BACKGROUND

Fluctuating cognition (FC), particularly in attention, is a core and defining symptom in dementia with Lewy bodies (DLB) but is seen much less frequently in Alzheimer's dementia (AD). However, its neurobiological origin is poorly understood. The aim of our study was therefore to characterize perfusion patterns in DLB patients that are associated with the severity and frequency of FC as measured both clinically and using objective neuropsychological assessments.

METHODS

Spatial covariance analyses were applied to data derived from single photon emission computed tomography (SPECT) HMPAO brain imaging in 19 DLB and 23 AD patients. Patients underwent clinical assessment of their FC and cognitive function as well as objective testing of their attention.

RESULTS

Covariant perfusion principal components (PCs) were not associated with either FC or cognitive or attentional measures in AD. However, in DLB patients, the second PC (defined as DLB-cognitive motor pattern, DLB-PCI2) which was characterized by bilateral relative increases in cerebellum, basal ganglia, and supplementary motor areas and widespread bilateral decreases in parietal regions, positively correlated with poorer cognitive function, increased FC and worse attentional function measured both clinically and neurophysiologically (p < 0.05) as well as with the severity of bradykinesia (p = 0.04).

CONCLUSIONS

FC in DLB appears distinct from those seen in AD, and likely to be driven by internal neurobiological perturbations in brain circuitry as evidenced using spatial covariance analyses of cerebral perfusion. FC and certain aspects of attentional dysfunction in DLB may, in part, depend upon both distributed motor and non-motor networks.

Applicability of the Rivermead Behavioural Memory Test - Third Edition (RBMT-3) in Korsakoff's syndrome and chronic alcoholics

PURPOSE

To examine the applicability of the newly developed Rivermead Behavioural Memory Test - Third Edition (RBMT-3) as an ecologically-valid memory test in patients with alcohol-related cognitive disorders.

PATIENTS AND METHODS

An authorized Dutch translation of the RBMT-3 was developed, equivalent to the UK version, and administered to a total of 151 participants - 49 patients with amnesia due to alcoholic Korsakoff's syndrome, 49 patients with cognitive impairment and a history of chronic alcoholism, not fulfilling the Korsakoff criteria, and 53 healthy controls. Between-group comparisons were made at subtest level, and the test's diagnostic accuracy was determined.

RESULTS

Korsakoff patients performed worse than controls on all RBMT-3 subtests (all P-values < 0.0005). The alcoholism group performed worse than controls on most (all P-values < 0.02), but not all RBMT-3 subtests. Largest effects were found between the Korsakoff patients and the controls after delayed testing. The RBMT-3 had good sensitivity and adequate specificity.

CONCLUSION

The RBMT-3 is a valid test battery to demonstrate everyday memory deficits in Korsakoff patients and non-Korsakoff patients with alcohol abuse disorder. Korsakoff patients showed an impaired performance on subtests relying on orientation, contextual memory and delayed testing. Our findings provide valuable information for treatment planning and adjustment in patients with alcohol-related cognitive impairments.

The diagnostic accuracy of dementia-screening instruments with an administration time of 10 to 45 minutes for use in secondary care: a systematic review

Early screening for dementia is crucial for identifying reversible causes as well as managing, counseling, and other therapeutic interventions. Many reviews have compared the suitability of very brief screening instruments for use in primary care, but reviews on more extensive instruments in secondary care are scarce. In addition, results on diagnostic accuracy are often biased due to methodological shortcomings, differences in the spectrum of patients or reporting. This systematic review reports the diagnostic accuracy of dementia-screening instruments with an administration time of 10 to 45 minutes, validated in secondary care, restricted to mild dementia and validation studies of ''high quality.'' Characteristics such as cognitive domains and reliability figures are also highlighted.