[Pathophysiology of dementia and medical imaging]

Dementia is not a particular disease but a clinical syndrome based on the subjective and objective symptoms. Morphological imaging modalities such as X-ray computed tomography (CT) and magnetic resonance imaging (MRI) can accurately identify those which can be treated. Functional imaging techniques such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) can visualize the regional decrease of neuronal function as mapping of cerebral blood flow and metabolism. Although they are useful for differential diagnosis and assessment of neuronal activity in patients with dementia, they cannot provide an information about the dementia itself. Recent rapid developments in molecular biology have started to clarify the underlying pathophysiology of various neurological diseases. A combination of these knowledge and the new imaging technique may bring an exciting new field in understanding the cause and the treatment of dementia.