| It has been commonly accepted that cognitive function impairment in the old is a dynamic progression, which can be separated into four steps:normal, age associated memory impairment (AAMI), mild cognitive impairment (MCI) and dementia. Unfortunately, few promising and effective treatment or intervention of dementia are, as of yet, available. Therefore, in order to reduce the risk of dementia and to develop better diagnostic tool, it is important to identify people who are high susceptibility or have been in the first stage. It has been thought that people diagnosed as amnestic MCI (aMCI) are much more susceptible to suffer Alzheimer’s disease (AD). However, assessments about aMCI are not reliable, and cutoff score in such assessments is confusing in China. Some neuroimaging studies have showed that people with dysfunction in temporal and parietal lobe have high risk to develop to AD from aMCI. Further researches are needed to estimate whether other regions are associated to this deterioration. In the present study, there are two main parts. Firstly, we are interested in the cutoff score of MMSE (Mini-Mental State Examination) in the community of the old, when age and education were taken into account. The cutoff score could be considered as a prerequisite of assessment of aMCI. Secondly, we aimed to investigate the corresponding underlying mechanism of aMCI by using SPECT and 18F-fluorodeoxyglucose- hybrid PET. We made comparison among patients with aMCI, AD patient (mild, moderate, and severe group), and health control (HC). As the result, firstly, we found that MMSE had a cutoff score 27 when participants’ education was primary school or below. Then, cutoff score of MMSE was 28 when participants’ education level was junior school or above. In addition, regardless of age, the cutoff score of MMSE was 28. Secondly, in terms of the findings by 18F-FDG-hPET and 99mTc-ECD-SPECT, we revealed hypometabolism in temporal lobe, parietal lobe and hippocampus in patients with aMCI, compared with health check (HC). Morever, reduced normalised radioactivity was detected in the cortex of AD patients. Specifically, hypometabolism and hypoperfusion were found in the frontal lobe, temporal lobe, parietal lobe and hippocampus in the patients with mild AD. By the development into modetare/severe stage of AD, hypometabolism and hypoperfusion were revealed in frontal lobe, tempral lobe, parietal lobe and occipital lobe. By taking cerebral metabolism, blood flow, age, education and neuropsychology assessment into account, we could draw two main conclusions. Firstly, cerebral metabolism are negetively correlated with age in both left and right sides of hippocampus, negatively correlated with ADL in right parietal lobe, positively correlated with WMS in left precuneus, thalamus and caudate nucleus, positively correlated with MMSR in left anterior angulate cortex, left precuneus, left caudate nucleus and left hippocampus. Secondly, cerebral blood flow were negatively related with education in right precuneus, anterior angulate cortex, thalamus and putamen, negatively related with ADL in right temporal lobe, positively related with ADL in left parietal lobe and right occipital lobe, positively related with WMS in left posterior cingulate cortex, positively related with MMSE in left caudate nucleus. In sum, the present study verified that cognitive function change can be seen as a progression from normal, aMCI to AD in the old. aMCI Patients with dysfunction in temporal and parietal lobe are highly susceptible to develop as AD, and dysfunction in parietal and occipital lobe can be seen as the earliest diagnostic symptom. |
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