[How far reaches earliness of optical coherence tomography in cognitive impairment]

INTRODUCTION

Alzheimer's disease (AD) is the leading cause of dementia in the world today. Increasingly greater efforts are being made to be able to detect cognitive impairment in earlier stages, and diagnostic entities such as mild cognitive impairment (MCI) and subjective memory complaints (SMC) are appearing. The number of biomarkers studied with the aim of reaching this goal continues to rise, and include optical coherence tomography.

SUBJECTS AND METHODS

The study conducted employed optical coherence tomography to measure the macular thickness and the retinal nerve fibre layer in patients diagnosed with AD (n = 36), in patients with MCI (n = 33), in individuals with SMC (n = 24) and in control subjects (n = 45).

RESULTS

Statistically significant differences have been found in terms of the macular thickness among all the groups studied (SMC: 261.8 ± 25.88 µm; MCI: 259.19 ± 22.582 µm; mild AD: 258.53 ± 14.804 µm; moderate AD: 249.32 ± 18.467 µm) and control subjects (271.96 ± 15.57 µm). The same occurs as regards the retinal nerve fibre layer and the difference is statistically significant compared with the control group (94.51 ± 9.203 µm) of all the groups (SMC: 90.44 ± 9.059 µm; MCI: 89.4 ± 10.421 µm; mild AD: 87.12 ± 10.279 µm; moderate AD: 82.25 ± 10.636 µm).

CONCLUSION

Optical coherence tomography could be a future biomarker and support tool to facilitate the early diagnosis of cognitive impairment and AD.

Addressing the bias problem in the assessment of the quality of life of patients with dementia: determinants of the accuracy and precision of the proxy ratings

OBJECTIVES

We aimed to examine the discrepancy between patients and caregivers' ratings of quality of life in terms of accuracy and precision, and identify factors associated with it, in order to facilitate the use of this scale as dementia progresses.

DESIGN

Cross-sectional analytic study.

SETTING

Day care centres.

PARTICIPANTS

Community-living patients with Alzheimer's disease in early or moderate stage and their principal caregivers.

MEASUREMENTS

PARTICIPANTS rated patients' quality of life using DEMQOL. The discrepancy was assessed using the individual difference score and the residuals for each domain of DEMQOL. The scores on Mini-Mental State Examination, Geriatric Depression Scale, Neuropsychiatric Inventory, Clinical Insight Rating Scale, Cumulative Illness Rating Scale, Health Utilities Index Mark 3 and Zarit Burden Interview were considered as possible predictors of the discrepancy.

RESULTS

A total of 276 subjects participated in the study (138 patients with Alzheimer's disease and their caregivers). Discrepancy measured by individual difference score was lower than that measured by the residuals. Burden and mood-related symptoms explained the positive differences and residuals, while pain, self-perceived depression and cognition determined the negative ones.

CONCLUSIONS

Differences exist between patients and caregivers' perceptions about subjective states. The evaluations of each informant seem to be influenced by their own emotional state and the inner experience of the effects of the disease. Caregivers' ratings on DEMQOL could be useful to monitor the efficacy of any treatment whenever burden is low and patients have no great physical or emotional suffering.

Changes in the neuronal activity in the pedunculopontine nucleus in chronic MPTP-treated primates: an in situ hybridization study of cytochrome oxidase subunit I, choline acetyl transferase and substance P mRNA expression

The pedunculopontine nucleus is a mesencephalic nucleus that has widespread and reciprocal connections with the basal ganglia. It has been implicated in the physiopathology of akinesia, rigidity, gait failure and sleep disorders associated with Parkinson's disease. In this study, in situ hybridization was used to examine the changes in neuronal metabolic activity (measuring cytochrome oxidase subunit I) and in the level of acetylcholine and Substance P synthesis in the pedunculopontine nucleus of monkeys chronically treated with MPTP. Significant reductions were observed in cytochrome oxidase subunit I (p = 0.001), choline acetyl transferase (p = 0.003) and substance P (p = 0.006) mRNA expression in parkinsonian animals compared with controls, indicating that pedunculopontine cholinergic neurons activity decreases with parkinsonism.