Comparison of general data of patients with mild and moderate AD
There were 13 patients in the mild AD group, 14 patients in the moderate AD group. There was no statistically significant difference between the mild and moderate AD group in terms of age, gender, education level, and course of disease (Additional table 1, P values > 0.05). The difference in the MMSE and MoCA scores between the two group was statistically significant (Additional table 1, P value < 0.0001).
Comparison of distribution characteristics of Aβ in patients with mild and moderate AD
Preliminary visual analysis revealed that among 27 AD patients, 22 had visible Aβ load, accounting for 81.48%. Compared with patients with mild AD, the range and degree of Aβ load were not significantly different in moderate AD. However, there were 5 patients (2 mild and 3 moderate AD patients) with no Aβ load in the cerebral cortex (Figure 1).
NeuroQ software divided the cerebral cortex into 30 different functional brain regions according to the Anatomical Automatic Labeling (AAL) method. In the present study, we used the number of brain areas with increased AV45 deposition to indicate the extent of brain areas involved. It was found that moderate patients had an average increase of 0.87 brain region with increased AV45 deposition compared with mild patients, but the difference between the two was not statistically significant (Table 1, P value = 0.25).
Further comparing the degree of Aβ load in the frontal, temporal, parietal and occipital lobes, it was found that there was no statistically significant differences in the degree of Aβ load between the patients with mild and moderate AD (Additional table 2, P values > 0.05).
Correlation between Aβ load and cognitive impairment in AD patients
In order to explore the relationship between Aβ load and cognitive impairment in AD patients, we analyzed the correlation of the range and degree of Aβ load in the functional areas of the frontal, temporal, parietal, occipital lobes and the total score of the MMSE and MoCA scales and subtests scores of MoCA. The results showed that the range of Aβ load in the cerebral cortex was not correlated with the total scores of MMSE and MOCA (Table 2, P value > 0.05). While the degree of Aβ load of the left superior parietal lobe, the left associative visual cortex, and the right Broca area was negatively correlated with the language and abstract reasoning subtest of MoCA (Additional table 3, P values are 0.02, 0.04, and 0.04, respectively).
Comparison of FDG metabolism reduction in patients with mild and moderate AD
According to the preliminary visual analysis, 26 of the 27 AD patients had a decrease of FDG metabolism, accounting for 96.30%. Compared with mild AD patients, the range and degree of FDG metabolism reduction was significantly increased in moderate AD. Only one mild AD patient had no reduction of FDG metabolism, and there was no Aβ load in any brain areas of this patient (Figure 2).
We used the number of brain areas with reduced FDG metabolism to indicate the extent of brain areas involved. Comparing the range of reduced FDG metabolism in 30 brain functional areas, we found an increase of 1.83 brain regions in moderate AD patients compared with mild AD patients and the difference between the two was statistically significant (Table 1, P value < 0.001).
Further comparing the degree of FDG metabolism, we found that the FDG metabolism reduction in some brain functional areas were significantly increased in moderate AD patients (Table 3).
Correlation between decreased FDG metabolism and impaired cognitive function in AD patients
To explore the relationship between decreased FDG metabolism and cognitive impairment in AD patients, the correlation of reduced FDG metabolism in brain functional areas and the total score of MMSE or the total score and subtest scores of MOCA were analyzed.
The results showed that 1) The range of reduced FDG metabolism in the cerebral cortex was negatively correlated with the total scores of MMSE or MoCA (Table 2, P value < 0.05); 2) The degree of FDG metabolism in some brain functional areas was positively correlated with the total score of MMSE scale or MoCA scale (Table 4); 3) The correlation between the degree of FDG metabolism and subtests scores of MoCA were shown in Additional table 4.