Selective serotonin reuptake inhibitors and Alzheimer’s disease

Given the failure to develop disease-modifying therapies for Alzheimer’s disease(AD),strategies aiming at preventing or delaying the onset of the disease are being prioritized.While the debate regarding whether depression is an etiological risk factor or a prodrome of AD rages on,a key determining factor may be the timing of depression onset in older adults.There is increasing evidence that untreated early-onset depression is a risk factor and that late-onset depression may be a catalyst of cognitive decline.Data from animal studies have shown a beneficial impact of selective serotonin reuptake inhibitors on pathophysiological biomarkers of AD including amyloid burden,tau deposits and neurogenesis.In humans,studies focusing on subjects with a prior history of depression also showed a delay in the onset of AD in those treated with most selective serotonin reuptake inhibitors.Paroxetine,which has strong anticholinergic properties,was associated with increased mortality and mixed effects on amyloid and tau deposits in mice,as well as increased odds of developing AD in humans.Although most of the data regarding selective serotonin reuptake inhibitors is promising,findings should be interpreted cautiously because of notable methodological heterogeneity between studies.There is thus a need to conduct large scale randomized controlled trials with long follow up periods to clarify the dose-effect relationship of specific serotonergic antidepressants on AD prevention.

Young blood products:emerging treatment for Alzheimer's disease?

Alzheimer＇s disease is the most common neurodegenerative disorder and no disease-modifying treatment is currently available.Research has shown that while brain neurogenesis continues in adult life,it declines with age.Using parabiosis,plasma transfusions and direct administration of neural growth factors,animal studies have demonstrated the positive impact of exposure to young blood products on neurogenesis and synaptic plasticity in an aging brain.The hippocampus and the sub-ventricular zones were identified as the main regions affected.Promising findings have prompted researchers to experiment their effects in subjects with an established neurocognitive disorder,such as Alzheimer＇s disease.They argued that modification of brain vasculature,reactivation of adult neural stem cells,and remodeling of their synaptic activity/plasticity may lead to cognitive enhancement and increased neurogenesis.One pilot human study found that young donor plasma infusion protocols for adults with Alzheimer＇s disease were safe and feasible;however,no statistically significant improvements in cognition were detected.There is a need to conduct additional placebo-controlled human studies in larger samples.Future studies should focus on identifying an “optimal age” at which an intervention in humans may yield significant cognitive enhancement,as well as determining the types of transfusions with the best efficacy and tolerability profiles.