Background Alzheimer's disease (AD) will become a prominent public health issue in the future given its cognitively debilitating nature. As the advent of global ageing society is expected, AD may bring tremendous socioeconomical costs if current diagnosis methods stay put. In this article, we performed a systematic review of a recent (less than 10 years) ultrasensitive technology, the immunomagnetic reduction (IMR), which shows promising potential of early diagnosis of AD. Methods We searched the Pubmed and Embase database for studies that included keywords “early-stage Alzheimer's disease” and “immunomagnetic signal reduction.” Results After full-text review, a total of 7 studies were included for final analysis. Most included studies have reported on Aβ40, Aβ42, t-tau, and levels of these biomarkers in the plasma of early AD patients comparing those in the healthy population. The ranges of the mean Aβ40 levels are as follows: 59.2 to 60.9 for control groups and 36.9 to 39.5 pg/mL for AD. Aβ42 and t-tau concentrations are both markedly lower than Aβ40, Aβ42 at 15.5 to 16.1 for control groups and 17.9 to 19 pg/mL for AD; t-tau levels were 13.5 to 14.3 for control groups and 39.4 to 46.7 pg/mL for AD. There is a significant increasing level of plasma Aβ42 by IMR assays in early AD patients across nearly all the included studies. There is a possible relationship between plasma levels of IMR AD biomarkers and (1) degree of hippocampal atrophy using magnetic resonance imaging, and (2) amount of brain amyloid accumulation using positron emission tomography. Conclusion IMR assay is an ultrasensitivity technique that is useful for detection of early AD, which can provide benefits on understanding the disease progression of AD and encourage early medical invention for AD patients.