Risk of dementia and mild cognitive impairment in older people with subjective memory complaints: meta-analysis

Objective: To investigate whether people with subjective memory complaints (SMC) but no objective deficits are at increased risk of developing mild cognitive impairment (MCI) and dementia. Method: Major electronic databases were searched till 03/2014, and a meta-analysis was conducted using inception cohort studies. Results: Across 28 studies, there were 29 723 unique individuals (14 714 with SMC and 15 009 without SMC) (mean 71.6 years) followed on average for 4.8 years through to dementia. The annual conversion rate (ACR) of SMC to dementia was 2.33% (95% CI = 1.93%–2.78%) a relative risk (RR) of 2.07 (95% CI = 1.76–2.44) compared with those without SMC (n = 15 009). From 11 studies the ACR of developing MCI was 6.67% (95% CI = 4.70–8.95%). In long-term studies over 4 years, 14.1% (9.67–19.1%) of people with SMC developed dementia and 26.6% (95% CI = 5.3–39.7) went on to develop MCI. The ACR from SMC to dementia and MCI were comparable in community and non-community settings. Conclusion: Older people with SMC but no objective complaints are twice as likely to develop dementia as individuals without SMC. Approximately 2.3% and 6.6% of older people with SMC will progress to dementia and MCI per year

Current Challenges for the Early Detection of Alzheimer's Disease: Brain Imaging and CSF Studies

The development of prevention therapies for Alzheimer's disease (AD) would greatly benefit from biomarkers that are sensitive to the subtle brain changes that occur in the preclinical stage of the disease. Reductions in the cerebral metabolic rate of glucose (CMRglc), a measure of neuronal function, have proven to be a promising tool in the early diagnosis of AD. In vivo brain 2-[18F]fluoro-2-Deoxy-D-glucose-positron emission tomography (FDG-PET) imaging demonstrates consistent and progressive CMRglc reductions in AD patients, the extent and topography of which correlate with symptom severity. There is increasing evidence that hypometabolism appears during the preclinical stages of AD and can predict decline years before the onset of symptoms. This review will give an overview of FDG-PET results in individuals at risk for developing dementia, including: presymptomatic individuals carrying mutations responsible for early-onset familial AD; patients with Mild Cognitive Impairment (MCI), often a prodrome to late-onset sporadic AD; non-demented carriers of the Apolipoprotein E (ApoE) ε4 allele, a strong genetic risk factor for late-onset AD; cognitively normal subjects with a family history of AD; subjects with subjective memory complaints; and normal elderly followed longitudinally until they expressed the clinical symptoms and received post-mortem confirmation of AD. Finally, we will discuss the potential to combine different PET tracers and CSF markers of pathology to improve the early detection of AD