Reduced N-acetylaspartate to creatine ratio in the posterior cingulate correlates with cognition in Alzheimer's disease following four months of rivastigmine treatment.

AIM: To determine whether 4 months of rivastigmine treatment would result in metabolic changes and whether metabolic changes correlate with changes in cognition in people with Alzheimer's disease (AD). METHODS: Magnetic resonance spectra were acquired from the posterior cingulate cortex of subjects with AD at 3 T. Magnetic resonance imaging scans and cognitive tests were performed before and 4 months after the beginning of the treatment. Metabolite concentrations were quantified and used to calculate the metabolite ratios. RESULTS: On average, the N-acetylaspartate/creatine (NAA/Cr) ratio decreased by 12.7% following 4 months of rivastigmine treatment, but changes in the NAA/Cr ratio correlated positively with changes in Mini-Mental State Examination scores. CONCLUSION: This positive correlation between changes in NAA/Cr and changes in cognitive performance suggests that the NAA/Cr ratio could be an objective indicator of a response to rivastigmine treatment.

Melatonin decreases delirium in elderly patients: a randomized, placebo-controlled trial.

BACKGROUND: Disturbance in the metabolism of tryptophan and tryptophan-derived compounds (e.g., melatonin) may have a role in the pathogenesis of delirium. OBJECTIVE: To evaluate the efficacy of low dose exogenous melatonin in decreasing delirium. DESIGN: A randomized, double-blinded, placebo-controlled study. SETTING: An Internal Medicine service in a tertiary care centre in London, Ontario, Canada. PARTICIPANTS: 145 individuals aged 65 years or over admitted through the emergency department to a medical unit in a tertiary care hospital. INTERVENTION: Patients were randomized to receive either 0.5 mg of melatonin or placebo every night for 14 days or until discharge. MEASUREMENTS: The primary outcome was the occurrence of delirium as determined by Confusion Assessment Method (CAM) criteria. RESULTS: Of a total of 145 individuals (mean age (standard deviation): 84.5 (6.1) years) 72 were randomly assigned to the melatonin group and 73 to the placebo group. Melatonin was associated with a lower risk of delirium (12.0% vs. 31.0%, p = 0.014), with an odds ratio (OR), adjusted for dementia and co-morbidities of 0.19 (95% confidence intervals (CI): 0.06-0.62). Results were not different when patients with prevalent delirium were excluded. LIMITATION: An intention to treat analysis was not possible due to loss to follow-up. CONCLUSION: Exogenous low dose melatonin administered nightly to elderly patients admitted to acute care may represent a potential protective agent against delirium.