请将这段话改写避免与原文出现连续5个字相同的句子使语言更高级逻辑更连贯：Several previous study showed that the expression of miR-137-5p was decreased in the blood of AD patients Therefore we further explore the molecular mechanism under

Several previous studies have indicated a decrease in miR-137-5p expression in the blood of individuals with AD. Consequently, we sought to investigate the intricate molecular mechanisms that underlie the involvement of miR-137-5p in the formation and progression of AD. Our study provides compelling evidence supporting the notion that AD patients exhibit decreased expression of miR-137-5p and increased expression of USP30. Furthermore, we have identified USP30 as a direct target of miR-137-5p. Intriguingly, our findings suggest that the restoration of miR-137-5p expression contributes to the toxicity and apoptosis induced by Ab1-42 through its targeting of USP30.