Neuroimaging Study in Dementia Syndrome---Clinical Analysis of Alzheimer's Disease , Dementia with Lewy Body and Fronto-Temporal Lobe Dementia

Alzheimer’s disease (AD) is the most common neurodegeneration disease leading to progressive cognitive decline in memory and other aspects of cognition. The duration from onset of symptoms to nursing home placement is about 5~7 years, and from symptom onset to death is 7~10 years. Dementia with Lewy bodies(DLB), or diffuse Lewy body disease, Lewy body dementia, senile dementia of Lewy body type, is the second commonest etiology of dementia in old population, particularly in 30% of those aged older than 80 years. The international workshop (1995) in Newcastle upon Tyne and (1998) in Amsterdam have published the international consensus diagnostic criteria of DLB. The major diagnostic factures of DLB include fluctuating cognitive impairment, parkinsonism and visual hallucination. Other minor supportive features include syncope, transient loss of consciousness, frequent falls, depression, delusion, sleep disorder, and neuroleptic hypersensitivity. Although the specificity of diagnostic criteria of DLB is high, the sensitivity is variable. There have been no CSF biomarkers to support a diagnosis of DLB. However neuroimaging studies can be helpful as a biomarker in differentiating the clinical diagnosis between AD and DLB. Brain magnetic resonance imaging (MRI) usually reveal a relative preservation of the medial temporal lobe particularly the hippocampus as compared with AD patients. Brain dopamine transporter (DAT) can be helpful in differential diagnosis between AD and DLB because of loss of DAT uptake in the caudate and putamen in dopaminergic single photon emission computed tomography (SPECT) in DLB and normal DAT in AD. Fronto-temporal lobe dementia (FTLD), or Pick disease once considered a rare disorder, is now the 3rd commonest cause of neurodegenerative dementia particularly inearly-onset dementia. The diagnosis of FTLD is based on clinical features including personality changes and language disturbance. Patients typically present in their 50s~60s with impairment in social comportment, language production or semantic knowledge. The clinical characteristics are overlapped among AD, DLB and FTLD. Accurate diagnosis of the dementia syndrome especially in the early stage of the disease is very important. Recently various neuroimaging studies may provide a very important structural and functional analysis among AD, DLB and FTLD. Particularly with recent studies of position emission tomography (PET) studies with β-amyloid (PIB) have shown an abnormal deposition in the brain cortex. Because the PIB is labeled with C-11 which is short in half life. The clinical application is restricted in only a few limited medical centers. Recently another new compound [18F]-AV-45 is labeled with F-18 and can be used to detect the Aβ plaque. The tracer, [18F]-AV-45 chemical name (E)-4-(2-(6-(2-(2-(2-[18F] fluoroethoxy)ethoxy)ethoxy)pyridine-3-yl)vinyl)N-methylbenzenamine) permits the visualization of amyloid in the brains of Alzheimer’s patients. In this project, we aim to study the clinical manifestations, and neuroimaging studies in DLB, FTLD as well as AD. We try to use the AV-45-compound PET to study the uptake pattern in AD, DLB and FTLD. To our knowledge, this compound has no advanced data in differential diagnosis among AD, DLB and FTLD.

Project ID:PC9808-0585
External Project ID:NSC98-2314-B182-056