Differential blood miRNA expression in brain amyloid imaging-defined Alzheimer's disease and controls

Background

Peripheral blood microRNAs (miRNA) have been identified as potential biomarkers for Alzheimer’s disease (AD). Study results have generally been inconsistent and limited by sample heterogeneity. The aim of this study is to establish candidate blood miRNA biomarkers for AD by comparing differences in miRNA expression between participants with brain amyloid imaging-defined AD and normal cognition.

Methods

Blood RNA was extracted from a subset of participants from the Australian Imaging Biomarkers Lifestyle Study of Ageing cohort (AIBL) with brain amyloid imaging results. MiRNA profiling was performed using small RNA sequencing on 71 participants, comprising 40 AD with high brain amyloid burden on imaging (amyloid positive) and 31 cognitively normal controls with low brain amyloid burden (amyloid negative). Cross-sectional comparisons were made between groups to examine differential miRNA expression levels using Fisher’s exact tests. Replication of results was undertaken using a publicly available dataset of blood miRNA data of AD and controls. In silico analysis of downstream messenger RNA targets of candidate miRNAs was performed to elucidate potential biological function.

Results

After quality control, 816 miRNAs were available for analysis. There were 71 significantly differentially expressed miRNAs between the AD and control groups (p < 0.05). Two of these miRNAs, miR-146b-5p and miR-15b-5p, were also significant in the replication cohort. Pathways analysis showed these miRNAs to be involved in innate immune system and regulation of the cell cycle, respectively, both of which have relevance to AD pathogenesis.

Conclusion

Blood miR-146b-5p and miR15b-5p showed consistent differential expression in AD compared to controls. Further replication and translational studies in strictly phenotyped cohorts are needed to establish their role as biomarkers for AD to have clinical utility.

Therapeutic effects of cerebrolysin added to risperidone in patients with schizophrenia dominated by negative symptoms

OBJECTIVE

Cerebrolysin is a nootropic drug with unique neurotrophic activities directly affecting cerebral neurons. This study evaluated the efficacy and safety of cerebrolysin added to risperidone in patients with schizophrenia dominated by negative symptoms.

METHODS

The trial was a double-blind, placebo-controlled, parallel-group design. A total of 109 patients who met the DSM-IV diagnostic criteria for schizophrenia were randomly assigned to cerebrolysin (cerebrolysin plus risperidone, n=55) or placebo (risperidone only, n=54) groups. Intravenous infusions of 30 ml cerebrolysin or placebo were given once daily from Monday to Friday for 4 weeks. Efficacy was assessed with measurements including the Positive and Negative Symptoms Scale (PANSS), Wechsler Memory Scale (WMS), modified Chinese Wechsler Adult Intelligence Scale (mWAIS). and Clinical Global Impression (CGI).

RESULTS

Patients in both groups demonstrated improvements in psychiatric symptoms and cognitive and memory performance as assessed by PANSS, mWAIS, and WMS over the trial. There was no difference in rates of change in the PANSS total score or negative score between the two treatment groups. Patients treated with cerebrolysin showed significantly greater improvements in cognitive and memory function from week 2. No severe treatment adverse events were observed in either group. The frequency of adverse events was comparable between the two groups at the end of the treatment.

CONCLUSION

Cerebrolysin added to risperidone did not augment the efficacy of risperidone in treating the psychotic symptoms of schizophrenia patients over an 8-week trial. Cerebrolysin at 30 ml per day as an adjunctive treatment was safe and may improve cognitive and memory functions of patients with schizophrenia dominated by negative symptoms.

Future research on dementia relating to culturally and linguistically diverse communities

About one in five older Australians were born overseas. However, there has been very little information published in Australia or internationally about dementia in persons from culturally and linguistically diverse (CALD) backgrounds. This limits our ability to plan for and provide evidence-based medical care, social care and aged care services to persons from CALD backgrounds. This paper describes challenges to conducting CALD dementia research; these include sampling, having valid instruments and costs. Nine key research recommendations in the areas of epidemiology, community knowledge, carers, service delivery, screening and assessment, medical management, residential aged care and minority CALD reached by consensus by an expert group are presented. The paper closes with some strategies to encourage CALD research. The material presented here will provide guidance for future research endeavours.

Differences in psychological morbidity among Australian and Chinese caregivers of persons with dementia in residential care

OBJECTIVE

The aim of the present study was to determine the effects of culture on caregiver psychological morbidity among informal caregivers of institutionalised persons with dementia in three different populations: (1) Shanghai, (2) Australian-Chinese and (3) Australian mainstream (non-Chinese).

METHODS

Caregivers and residents with dementia were recruited from (1) a dementia hospital in Shanghai, (2) three ethno-specific Chinese nursing homes in Sydney and (3) four mainstream nursing homes in Sydney. Psychological morbidity was assessed using the Geriatric Depression Scale, mental health component (MHC) of the RAND-36 Health Status Inventory and a guilt scale.

RESULTS

There were no significant differences between the three groups as measured by the guilt scale and MHC. Shanghai caregivers had higher mean depression scores than Australian-Chinese caregivers (p < 0.001), who in turn had higher mean depression scores than Australian mainstream caregivers (p = 0.015). Higher depression scores were found to be inversely associated with the caregiver's education level and physical health status, and associated with increased frequency of nursing home visits, but not with levels of behavioural and psychological symptoms of dementia (BPSD).

CONCLUSION

Levels of depression in caregivers of institutionalised persons with dementia differ by culture and country of residence.