[Recent advances in Alzheimer's disease research]

Vascular dementia (VD) and Alzheimer's disease (AD) are two main causes of dementia in the aged. Recent epidemiological studies in Japan indicate that the incidence of AD is becoming slightly higher than that of VD. Among various approaches to clarify the etiology of AD, research through the mechanism of formation of senile plaque and neurofibrillary tangle, which characterize AD pathology, seems to be the most orthodox as well as fruitful. Genetic studies on hereditary AD reveal that the etiologies of AD are heterogeneous, but the deposition of beta amyloid followed by the accumulation of abnormally phosphorylated tau-protein seems to be the common process specific to AD. In regards to the clinical problems of AD, development of the diagnostic markers for early definite diagnosis and effective therapeutic agents is most urgent. The index of A beta 40/A beta 42 x tau calculated from measurements of A beta and tau levels in cerebrospinal fluid is the best marker at present. On the other hand, many antidementia drugs are now on trial. Most of them are acetylcholine stimulating agents, including tacrine and donepezil, which have been admitted recently in the USA and some other countries. Such drugs which suppress the development of AD should be called true antidementia agents, but the present drugs are not true antidementia drugs.