KR102341233B1 - Novel biomarker microRNA for diagnosing mild cognitive impairment or early Alzheimer's disease - Google Patents

Abstract

The present invention relates to a novel microRNA biomarker for the early diagnosis of mild cognitive impairment or Alzheimer's dementia. A novel microRNA of SEQ ID NO: 1 or SEQ ID NO: 3 obtained by a molecular-based analysis of the present invention is expressed in the plasma of a patient group with mild cognitive impairment and Alzheimer's dementia, and has the effect of reducing the expression of proteins associated with mild cognitive impairment and Alzheimer's dementia. By utilizing novel microRNA present in plasma with relatively low invasiveness as a molecular diagnostic index, the present invention has the effect of enabling early diagnosis before the emergence of symptoms of mild cognitive impairment or Alzheimer's dementia.

Description

Novel biomarker microRNA for diagnosing mild cognitive impairment or early Alzheimer's disease

The present invention relates to a novel microRNA biomarker for early diagnosis of mild cognitive impairment or Alzheimer's dementia.

Currently, Alzheimer's dementia is diagnosed through neuropsychological examination and imaging based on the cognitive impairment and amyloid hypothesis. Efforts are being actively pursued.

miRNA is a single-stranded small RNA with about 20 nucleotide sequences, a short sequence that binds to 3'-UTR (3'-untranslated regions) of a specific target mRNA and regulates protein through translational inhibition of mRNA is the RNA of About 1,000 miRNAs have been identified so far in humans, but most of the miRNAs have unknown functions.

Currently, the analysis of dementia using blood mainly relies on protein, but there is a significant difference between patients compared to structural stability, and there are disadvantages in that the pathology of Alzheimer's dementia cannot be fully reflected in blood. In order to derive a more sensitive diagnostic index, a smaller size target is required. In particular, in the case of Alzheimer's dementia, since the aggregation of abnormal proteins is induced by various environmental stimuli rather than by genetic factors, the fundamental target is analyzed by analyzing changes in gene expression regulation prior to protein translation, rather than protein results. It is considered to be important to find. When miRNA is used as a diagnostic index, it is a single-stranded RNA of 21 to 25 nucleotides present in all living fluids, including blood, urine, and saliva, and plays a role in directly controlling gene expression by inhibiting the translation of mRNA. In addition, it is resistant to degradation by RNase and is stably present in the blood, and defects in miRNA metabolism or function are closely related to the onset of dementia. have.

For the diagnosis of Alzheimer's disease, it is very important to take an accurate history through the report of a caregiver who knows the patient best. The doctor will check if there is any change in cognitive function, including memory, compared to before, and if so, when and how it appeared, and biochemical tests such as physical examination, neurological examination, mental state examination, daily living function level test, blood test, etc. , brain imaging tests, neuropsychological tests, etc. However, there are still several limitations in diagnosing Alzheimer's disease, making early diagnosis difficult. Mainly, Alzheimer's dementia is diagnosed through neuropsychological examination and imaging based on the cognitive impairment and amyloid hypothesis. is being done

On the other hand, miRNA is a single-stranded small RNA with about 20 base sequences. It is a short sequence of RNA. About 1,000 human miRNAs have been identified so far, but most of them have unknown functions.

Dementia analysis using blood mainly relies on protein, but compared to structural stability, patient-specific deviations are severe and the pathology of Alzheimer's dementia cannot be fully reflected in blood. You need a target. In particular, in the case of Alzheimer's dementia, since the aggregation of abnormal proteins is induced by various environmental stimuli rather than by genetic factors, the fundamental target is analyzed by analyzing changes in gene expression regulation prior to protein translation, rather than protein results. It is important to find

For example, when miRNA is used as a diagnostic index, it is a single-stranded RNA of 21 to 25 nucleotides present in all biological fluids including blood, urine and saliva, and serves to directly control gene expression by inhibiting the translation of mRNA. In addition, it is resistant to degradation by RNase and is stably present in the blood, and defects in miRNA metabolism or function are closely related to the onset of dementia. have.

On the other hand, as a diagnosis-related technology for cognitive dysfunction, Korean Patent No. 1992539 discloses a miRNA-based composition and method for diagnosing cognitive impairment, and Korean Patent No. 1718940 discloses Alzheimer's dementia or welfare for mild cognitive impairment. Although a composition for early diagnosis of genetics has been disclosed, a novel microRNA biomarker for early diagnosis of mild cognitive impairment or Alzheimer's dementia of the present invention has not been disclosed yet.

The present invention has been derived from the above needs, and the present invention provides a novel micro RNA biomarker for early diagnosis of mild cognitive impairment or Alzheimer's dementia, and the novel miRNA of SEQ ID NO: 1 or SEQ ID NO: 3 according to the present invention is expressed in the plasma of the mild cognitive impairment patient group and the Alzheimer's dementia patient group for early diagnosis of mild cognitive impairment or Alzheimer's dementia, and confirmed that the expression of Alzheimer's dementia-related protein can be reduced, thereby completing the present invention.

In order to achieve the above object, the present invention provides a biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia comprising a novel microRNA comprising the nucleotide sequence of SEQ ID NO: 1 or SEQ ID NO: 3 as an active ingredient.

In addition, the present invention provides a biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia, comprising as an active ingredient an agent capable of detecting microRNA consisting of the nucleotide sequence of SEQ ID NO: 1 or SEQ ID NO: 3.

In addition, the present invention provides a kit for early diagnosis of mild cognitive impairment or Alzheimer's dementia comprising the biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia as an active ingredient.

In addition, the present invention comprises the steps of (1) collecting blood from a subject;

(2) separating plasma from the blood of step (1); and

(3) confirming whether miRNA expression of SEQ ID NO: 1 or SEQ ID NO: 3 in the plasma isolated in step (2) is provided; a method of providing information for early diagnosis of mild cognitive impairment or Alzheimer's dementia, including; to provide.

The present invention relates to a novel microRNA biomarker for early diagnosis of mild cognitive impairment or Alzheimer's dementia, wherein the novel miRNA of SEQ ID NO: 1 or SEQ ID NO: 3 according to the present invention is expressed in the plasma of a group of patients with mild cognitive impairment, Alzheimer's It has the effect of reducing the expression of dementia-related proteins. Therefore, the present invention has the effect of enabling early diagnosis before the symptoms of Alzheimer's dementia appear by utilizing the novel miRNA present in plasma with relatively low invasiveness as a diagnostic index.

1 shows the stem loop structure and sequence information of the novel miRNA2 identified in the present invention.
Figure 2 shows the stem loop (stem loop) structure and sequence information of the novel miRNA3 confirmed in the present invention.
Figure 3 shows mimic and inhibitor synthesis sequences of miRNA2 (A) and miRNA3 (B) for confirming the novel miRNA function of the present invention.
Figure 4 is a Western blot result confirming the expression level of the novel miRNA2 target gene proteins BDNF, NRG3 and NEFL of the present invention. *, **, *** indicates that there is a statistically significant difference in target gene expression level between the control group untreated and the group treated with miRNA mimic or miRNA inhibitor of the present invention, * is p<0.05, ** is p<0.01, *** is p<0.001.
5 is a Western blot result confirming the change in the expression level of the novel miRNA3 target gene protein HOOK3 of the present invention. * and *** indicate that there is a statistically significant difference in target gene expression level between the control group untreated and the group treated with miRNA mimic or miRNA inhibitor of the present invention, * is p <0.05, *** is p <0.001.
6 is a result of confirming the change in the expression level of the novel miRNA3 target gene protein HOOK3 of the present invention by immunocytochemistry.

The present invention relates to a biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia comprising a novel microRNA comprising the nucleotide sequence of SEQ ID NO: 1 or SEQ ID NO: 3 as an active ingredient.

In the present invention, micro RNA (miRNA) refers to 21 to 23 non-coding RNAs that regulate gene expression after transcription by promoting degradation of target RNA or inhibiting their translation. Not only miRNAs represented by specific nucleotide sequences, but also precursors of the miRNAs (pre-miRNA, pri-miRNA), miRNAs having biological functions equivalent to them, such as homologues (i.e., homologs or orthologs), variants such as polymorphisms, and derivatives.

The novel microRNA is preferably derived from human plasma, but is not limited thereto.

The novel micro-RNA of SEQ ID NO: 1 reduces the expression levels of BDNF (Brain-Derived Neurotrophic Factor), NRG3 (Neuregulin3) and NEFL (Neurofilament Light Chain) genes, and the novel micro-RNA of SEQ ID NO: 3 is HOOK3 (Protein Hook homolog) 3) It is characterized by reducing the expression level of the gene.

The 'diagnosis' of the present invention is to determine the susceptibility of an object, that is, a test subject, to a specific disease or disorder, to determine whether an object currently has a specific disease or disorder, Concepts involving determining the prognosis of an affected subject or therametrics (eg, monitoring a subject's condition to provide information on treatment efficacy).

In addition, the present invention relates to a biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia, comprising as an active ingredient an agent capable of detecting a microRNA comprising the nucleotide sequence of SEQ ID NO: 1 or SEQ ID NO: 3.

The agent may be an antisense oligonucleotide, primer, or probe complementary to the microRNA, but is not limited thereto.

Mild cognitive impairment refers to an intermediate stage between cognitive decline and dementia due to normal aging. In other words, it refers to a state in which cognitive abilities are lowered compared to those of the same age group, and it is different from dementia in that it is possible to carry out daily life. This mild cognitive impairment is an intermediate stage between normal and dementia, and is known as a high-risk group for dementia.

Therefore, in the present invention, the 'mild cognitive impairment or Alzheimer's dementia patient group' was adopted as an experimental group for early diagnosis of mild cognitive impairment or Alzheimer's dementia.

In addition, the present invention comprises a biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia comprising as an active ingredient an agent capable of detecting a novel microRNA consisting of the nucleotide sequence of SEQ ID NO: 1 or SEQ ID NO: 3 as an active ingredient. It relates to a kit for early diagnosis of mild cognitive impairment or Alzheimer's dementia.

The kit is preferably for RT-PCR, real-time PCR, isothermal PCR, northern blotting, RNA protection assay or microarray chip, but is not limited thereto.

The kit of the present invention may additionally include a nucleic acid capable of specifically binding to the microRNA of SEQ ID NO: 1 or SEQ ID NO: 3, wherein the nucleic acid is RNA, DNA, or RNA/DNA (chimera). The DNA may include all of cDNA, genomic DNA, and synthetic DNA.

In addition, the RNA may include total RNA, mRNA, rRNA, miRNA, siRNA, snoRNA, snRNA, non-coding RNA, and synthetic RNA. The kit of the present invention may include a known nucleic acid or a nucleic acid that can be discovered in the future that enables early diagnosis of Alzheimer's dementia in addition to the nucleic acid, and an antibody for measuring a known marker for early diagnosis of Alzheimer's dementia can also be included. The nucleic acids included in the kit may be packaged in different containers individually or in any combination.

The kit of the present invention may include a fluorescent material for labeling, an enzyme and medium for nucleic acid amplification, instructions for use, and the like. The kit of the present invention is a device for early diagnosis of Alzheimer's dementia in which the nucleic acid is bound or attached to a solid phase, for example. Examples of the solid material include plastic, paper, glass, silicone, and the like, and a preferred solid material from the viewpoint of ease of processing may be plastic. The shape of the solid phase is arbitrary, and may be, for example, a square, a circle, a rectangle, a film shape, and the like.

The kit of the present invention may be included in a device for high-throughput-screening (HTS)-based multiplexed POCT that simultaneously processes a large amount of miRNA samples. The cartridge in the device can consist of a thermostat, agitator, disposable tip, and sample injection container. When human blood is injected with an all-in-one device with a built-in ultra-small whole blood separator, fluorescence detector, and liquid handler, a 'dementia risk index' is automatically derived. Algorithms and fully automatic detection systems may be included.

In addition, the present invention comprises the steps of (1) collecting blood from a subject;

(2) separating plasma from the blood of step (1); and

(3) confirming the expression of miRNA of SEQ ID NO: 1 or SEQ ID NO: 3 in the plasma isolated in step (2); In a method of providing information for early diagnosis of mild cognitive impairment or Alzheimer's dementia, including it's about

Hereinafter, the present invention will be described in more detail using examples. These examples are only for illustrating the present invention in more detail, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited thereto.

1. Securing samples from Alzheimer's dementia patients

Mild cognitive impairment (MCI) and Alzheimer's disease (AD) among the patient groups classified according to the severity of Alzheimer's disease through screening tool (K-MMSE, SNSB) scores and imaging diagnostics (PET, fMRI, CT) Blood was collected from 10 patients per classified patient group and plasma was isolated. The separated plasma was stored frozen at -70°C until use. Meanwhile, as a control group, blood was collected from 10 normal people, plasma was separated, and stored frozen at -70°C until used in the same manner as in the patient group.

2. Total miRNA extraction

Total RNA in each plasma of the obtained patient group and normal group was extracted using the QIAGEN miRNeasy Serum/Plasma Separation Kit, which can mainly purify miRNA and other small RNAs from a small amount of serum and plasma.

Thereafter, it was confirmed whether a sufficient amount of RNA was secured for library production for NGS analysis using the Bioanalyzer RNA Small RNA chip.

3. Next Generation Sequencing (NGS) analysis

A small RNA-seq library was generated on the Illumina Platform using the SMARTer smRNA-Seq Kit, which can produce a high-quality miRNA library even with a small amount of RNA. Prepared samples were sequenced with the NovaSeq 6000 sequencing platform according to the SMARTer smRNA-Seq Kit manual.

4. Selection of miRNA data through raw data analysis

In the order of trimming of adapter, quality, and length of the raw data obtained by NGS analysis, contaminating or small data present in plasma were removed. Through this trimming process, miRNA Deep2* sequencing was performed with clean data from which unnecessary information was removed.

5. miRNA Deep2* Sequencing

miRNA Deep2* is a software that can identify new miRNAs from purified raw data. According to the RNAfold algorithm, miRBase (Pre-miRNA) libraries cut short in mature, star and loop sequences are arranged side by side to predict new miRNAs. The RNAfold algorithm can be derived in a way that predicts the secondary structure of the RNA sequence with the least free energy using the most similar thermodynamic model. The RNA fold generation graphic includes the number of reads for each part of the hairpin, the score for the least free energy, the score for the randfold, and the conserved seed sequence score.

The miRDeep2* system can detect known miRNAs and new miRNAs by mapping using an RNA database.

6. Verification of novel miRNA related to Alzheimer's disease reflected in blood

For functional verification of how novel miRNAs are related to Alzheimer's dementia, they were screened using miRDB software that scores target genes (miRNAs) based on the sequence of miRNAs. It was verified through expression level analysis of genes related to Alzheimer's dementia among target genes with high gene scores.

SH-SY5Y cells used as models for neural function and differentiation were used, and a miRNA mimic showing the overexpression effect of selected new miRNAs, a miRNA inhibitor that suppresses the expression of new miRNAs, and a negative control miRNA were transfected into SH-SY5Y After injection, the protein expression of the target gene was confirmed by Western blot.

Example 1. Sample acquisition and total RNA extraction

Using the QIAGEN miRNeasy Serum/Plasma Kit, which can purify miRNA and other small RNAs from a small amount of serum and plasma, total RNA in each plasma collected from the patient group and the normal group was extracted. Afterwards, it was confirmed that a sufficient amount of RNA was secured for NGS analysis by quantifying RNA using the Bioanalyzer RNA Small RNA chip to see if a sufficient amount of RNA was secured for library production for NGS.

Example 2. Next Generation Sequencing (NGS)

(1) Library construction and raw data derivation

In generating a small RNA-seq library for sequencing on the Illumina Platform for NGS, SMARTer smRNA-Seq Kit, which can produce high-quality miRNA libraries even from a small amount of RNA, was used. A library was prepared for sequencing the total RNA of the patient group and the normal group obtained from plasma, and sequencing was performed using the prepared library and the NovaSeq 6000 sequencing platform to derive raw data.

(2) Selection of miRNA data from raw data

The raw data obtained from NGS analysis was trimmed in the order of Adapter, Quality, and Length to remove contaminated or small amount of data.

In Total Read Count, which is the raw data obtained by sequencing, the presence of adapter (nonAdapter Read Count), appropriate length (Short Read Count), and low quality (Low Quality Read Count) were checked. miRNA Deep2* sequencing was performed using the primary processing data from which information has been removed.

(3) miRNA Deep2* sequencing

miRNA Deep2* predicts new miRNAs by arranging miRBase (Pre-miRNA) libraries cut short in mature, star, and loop sequences according to the software's RNAfold algorithm that can identify newly known miRNAs from the primary processed data. The RNAfold algorithm was derived in a way that predicts the secondary structure of the RNA sequence with the minimum free energy using the most similar thermodynamic model.

The RNA fold generation graphic includes the number of reads for each part of the hairpin, the score for the minimum free energy, the score for the randfold, and the conserved seed sequence score. The miRDeep2* system detected known miRNAs and new miRNAs by mapping using an RNA database.

The final processed reads for each sample were classified into piRNA, tRNA, snRNA, snoRNA, known miRNA and novel miRNA through miRBase v22.1 and non-coding RNA database (RNAcentral release 14.0).

Genome mapping was processed by Bowtie and STAR using RSEM. Bowtie then used the genome sequence for miRDeep2 analysis. Known/new miRNAs predicted by miRDeep2 and other small RNAs consistent with RNAcentral were aligned using Bowtie (target small RNA, <50nt) and Bowtie2 (target smRNA, ≥50nt).

- RSEM (RNA-Seq by Expectation-Maximization): A tool to quantify RNA-Seq transcripts

- Bowtie: software commonly used for sequence alignment and sequencing

- STAR (Spliced Transcripts Alignment to a Reference): fast RNA-seq read mapper

To predict novel miRNAs, unique clustered reads were separately aligned against the reference genome and precursor miRNAs. miRNAs can predict mature star and loop sequences according to the RNAfold algorithm using miRNA Deep2*. The RNAfold function predicted the least free energy secondary structure of the RNA sequence using the nearest neighbor thermodynamic model. Graphics generated from RNAfold contain actual in silico-folded hairpins, as well as the number of reads for each part of the hairpin, the minimum free energy score, and the randfold score and the score of the conserved seed sequence.

miRDeep2* derived a novel miRNA through a score of -10 to 10. The new miRNAs derived above were expressed in both the mild cognitive impairment group and the Alzheimer's disease group. Among them, two miRNAs with a miRDeep2* score of 1 or more, an RNA fold of "yes", and a number of mature reads of 10 or more were selected.

The stem loop structures of the selected novel miRNA2 and miRNA3 were disclosed in FIGS. 1 and 2 , and sequence information was disclosed in FIG. 3 .

Example 3. Confirmation of control of gene expression level related to Alzheimer's dementia by novel miRNA

In order to verify how the novel miRNA is related to Alzheimer's dementia, miRDB software was used that screens target genes by score based on the sequence of the miRNA. Among the target genes having a high gene score, genes related to Alzheimer's dementia were selected.

SH-SY5Y cells used as a model for neural function and differentiation were used. After transfection of a miRNA mimic that shows the overexpression effect of selected new miRNAs, a miRNA inhibitor that suppresses the expression of new miRNAs, and a negative control miRNA into SH-SY5Y , The protein expression of the target gene was confirmed by Western blot.

miRNA mimic is actually a miRNA that can function like a novel miRNA in a living body, and was made with a double bond. A miRNA inhibitor is a complementary sequence of the derived miRNA, and is a miRNA that is produced as a single bond and can inhibit the corresponding miRNA. On the other hand, the negative control miRNA is a miRNA composed of miRNAs that do not regulate genes, and serves as a verification standard. mimic of the novel miRNA2 and miRNA3 produced; and miRNA inhibitors were disclosed in FIG. 3 .

[ Gene screening using miRDB software ]

Among the genes controlled by the new miRNA, in order to select a target highly related to Alzheimer's dementia, the miRNA 2 mimic among the novel miRNAs is based on the sequence 5'-UAAAGAGGAAAGAGGAAAGAGG-3' (SEQ ID NO: 1), and the miRNA 3 mimic is the sequence Based on 5'-CGGGAGGCAGCAGUGGGC-3' (SEQ ID NO: 3), the genes were screened by score using the target prediction miRDB software. The miRNA inhibitor for miRNA mimic of SEQ ID NO: 1 is 5'-CCUCUUUCCUCUUUCCUCUUUA-3' (SEQ ID NO: 2), and the miRNA inhibitor for miRNA mimic of SEQ ID NO: 3 is 5'-GCCCACUGCUGCCUCCCG-3' (SEQ ID NO: 4).

After setting the cut-off value of the gene score of the corresponding miRNA to 80, synaptic transmission and synaptic plasticity as well as neuronal survival and differentiation in the central nervous system as a miRNA2 target gene related to nerve and synaptic function, and as neurotrophins BDNF (Brain-Derived Neurotrophic Factor), which is essential for the molecular mechanism of Light Chain), NRG3 (Neuregulin3), which regulates the growth and differentiation of epithelial and glial cells, and plays an important role in the development, maintenance and repair of the nervous system, was selected. As a cytoplasmic linker gene, a target gene HOOK3 (Protein Hook homolog 3) related to the production of amyloid beta, a protein that causes Alzheimer's dementia, was selected.

100 nM of each miRNA was transfected into human neuroblastoma SH-SY5Y with miRNA mimic for overexpression of novel miRNA and miRNA inhibitor for function inhibition for 24 hours, and the protein was isolated and the expression level was confirmed by Western blot.

It was confirmed that the expression of candidate target gene proteins, BDNF, NRG3, and NEFL, was significantly decreased due to the overexpression of new miRNA2, which resulted in more miRNA2 binding to 3'-UTR, and miRNA2 binding to 3' was removed with a miRNA inhibitor. By doing so, it was confirmed that the expression of candidate target gene proteins BDNF, NRG3 and NEFL increased in a concentration-dependent manner ( FIG. 4 ).

On the other hand, miRNA3 mimic for overexpression of novel miRNA3 and miRNA3 inhibitor for function inhibition were transfected into human neuroblastoma SH-SY5Y with mimic of miRNA3 and inhibitor, respectively, for 24 hours in a concentration-dependent manner, and protein was isolated and western A blot was performed. It was confirmed that the expression of HOOK3, a candidate target gene protein, was significantly reduced during miRNA 3 mimic treatment, which shows the effect of novel miRNA 3 overexpression. For miRNA 3 inhibitor treatment, it was confirmed that the expression of HOOK3 was increased (FIG. 5).

In addition, after the miRNA mimic and miRNA inhibitor concentrations were fixed at 1 nM, the expression of HOOK3 protein of the target gene was compared by immunocytochemistry. As a result, it was confirmed that the expression pattern was consistent with the Western blot (FIG. 6).

<110> Alz-Dementia Korea Co. <120> Novel biomarker microRNA for diagnosing mild cognitive impairment or early Alzheimer's disease <130> PN21288 <160> 4 <170> KoPatentIn 3.0 <210> 1 <211> 22 <212> RNA <213> Homo sapiens <400> 1 uaaagaggaa agaggaaaga gg 22 <210> 2 <211> 22 <212> RNA <213> Homo sapiens <400> 2 ccucuuuccu cuuuccucuu ua 22 <210> 3 <211> 18 <212> RNA <213> Homo sapiens <400> 3 cgggaggcag cagugggc 18 <210> 4 <211> 18 <212> RNA <213> Homo sapiens <400> 4 gccccacugcu gccucccg 18

Claims (12)

A biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia comprising a novel microRNA comprising the nucleotide sequence of SEQ ID NO: 1 or SEQ ID NO: 3 as an active ingredient. The biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia according to claim 1, wherein the novel microRNA is derived from human plasma. According to claim 1, wherein the novel micro-RNA of SEQ ID NO: 1 reduces the expression levels of BDNF (Brain-Derived Neurotrophic Factor), NRG3 (Neuregulin3), and NEFL (Neurofilament Light Chain) genes, and the novel micro-RNA of SEQ ID NO: 3 is a biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia, characterized in that it reduces the expression level of the HOOK3 (Protein Hook homolog 3) gene. A biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia, comprising as an active ingredient an agent capable of detecting microRNA consisting of the nucleotide sequence of SEQ ID NO: 1 or SEQ ID NO: 3. The biomarker composition for early diagnosis of mild cognitive impairment or Alzheimer's dementia according to claim 4, wherein the agent is an antisense oligonucleotide, primer, or probe complementary to the microRNA. A kit for early diagnosis of mild cognitive impairment or Alzheimer's dementia comprising the composition of claim 4 as an active ingredient. The kit for early diagnosis of mild cognitive impairment or Alzheimer's dementia according to claim 6, wherein the kit is for RT-PCR, real-time PCR, isothermal PCR, Northern blotting, RNA protection assay, or microarray chip. . The kit for early diagnosis of mild cognitive impairment or Alzheimer's dementia according to claim 6, wherein the kit is for a high-throughput-screening (HTS)-based multiplexed POCT device. The kit for early diagnosis of mild cognitive impairment or Alzheimer's dementia according to claim 8, wherein the multiplexed POCT device comprises a thermostat, a stirrer, a disposable tip, and a sample injection container. The kit for early diagnosis of mild cognitive impairment or Alzheimer's dementia according to claim 8, wherein the multiplexed POCT device is an all-in-one device with a built-in ultra-small whole blood separator, a fluorescence detector and a liquid handler. [Claim 11] The mild cognitive impairment or early Alzheimer's dementia according to claim 10, wherein the ultra-small whole blood separator, the fluorescence detector and the liquid handler are embedded in an algorithm and detection system for calculating the dementia risk index from human blood. Diagnostic kit. delete

Images