Clinical trials of amyloid-based therapies for Alzheimer's disease

Mechanism-based treatments for Alzheimer's disease

Treatment for Alzheimer's disease is entering a new and exciting phase, with several new drugs beginning clinical trials. Many of these new therapies are based on our best current understanding of the pathogenesis of Alzheimer's disease, and are designed to try to either slow or halt the progression of the disease. There are several different theories underlying the current efforts, and these are briefly reviewed. Therapies directed against some aspect of β-amyloid formation, against neurofibrillary tangle formation and against the inflammatory response are all considered, as are the problems associated with each area. It is as yet unclear which, if any, of these approaches will be successful, but the high level of activity in each of these three fields provides some hope that an effective treatment for Alzheimer's disease is on the horizon.

CSF biomarkers, impairment of cerebral hemodynamics and degree of cognitive decline in Alzheimer's and mixed dementia

The in vivo diagnosis of Alzheimer's disease (AD) may be facilitated by cerebro-spinal fluid (CSF) biomarkers in combination with imaging and clinical assessments. By determining the concentration of beta amyloid fragments, total tau (t-tau) and phospho-tau (p-tau), it is possible to detect the conversion of mild cognitive impairment (MCI) to AD or distinguish AD vs. pseudo-dementia. However, these markers are poorly sensitive to the progressive disease stages. And far from clear is their role in "mixed" forms of dementia, as far as hemodynamic deficits complicate the clinical history. We have studied cerebral hemodynamic impairment in AD patients, relative to control subjects. Mean flow velocity (MFV), pulsatility index (PI) and cerebrovascular reactivity (assayed as breath-holding index, BHI) were evaluated by bilateral transcranial Doppler (TCD) monitoring of middle cerebral arteries. MFV and BHI were significantly lower and PI was significantly higher in AD patients with respect to control subjects. The presence of white-matter changes (WMC) in the AD cases did not influence any of the hemodynamic variables. Noticeably, MMSE score was correlated to BHI reduction (P<0.005). Our results, consistent with the recent literature indicate that hemodynamic impairment is a critical marker of cognitive decline and supports once more the hypothesis of a significant pathigenic role of vascular damage in AD. Similar functional alterations might be early hallmarks in a variety of dementia subtypes, including "mixed" dementia, whose prevalence is undoubtedly increased. Assessment of hemodynamic reactivity could provide valuable correlations with individual patient's cognitive profile, which in turn would assist in the identification of critical steps in disease progression and the validation of effective therapies.

Mechanism-based treatments for Alzheimer's disease

Treatment for Alzheimer's disease is entering a new and exciting phase, with several new drugs beginning clinical trials. Many of these new therapies are based on our best current understanding of the pathogenesis of Alzheimer's disease, and are designed to try to either slow or halt the progression of the disease. There are several different theories underlying the current efforts, and these are briefly reviewed. Therapies directed against some aspect of beta-amyloid formation, against neurofibrillary tangle formation and against the inflammatory response are all considered, as are the problems associated with each area. It is as yet unclear which, if any, of these approaches will be successful, but the high level of activity in each of these three fields provides some hope that an effective treatment for Alzheimer's disease is on the horizon.