Re: '스퍼미딘' 인지기능 개선 JAMA RCT 2022

[문형철]

Original Investigation 

Neurology

Effects of Spermidine Supplementation on Cognition and Biomarkers in Older Adults With Subjective Cognitive DeclineA Randomized Clinical Trial

JAMA Netw Open

Published Online: May 26, 2022

2022;5;(5):e2213875. doi:10.1001/jamanetworkopen.2022.13875

Importance  Developing interventions against age-related memory decline and for older adults experiencing neurodegenerative disease is one of the greatest challenges of our generation. Spermidine supplementation has shown beneficial effects on brain and cognitive health in animal models, and there has been preliminary evidence of memory improvement in individuals with subjective cognitive decline.

Objective  To determine the effect of longer-term spermidine supplementation on memory performance and biomarkers in this at-risk group.

Design, Setting, and Participants  This 12-month randomized, double-masked, placebo-controlled phase 2b trial (the SmartAge trial) was conducted between January 2017 and May 2020. The study was a monocenter trial carried out at an academic clinical research center in Germany. Eligible individuals were aged 60 to 90 years with subjective cognitive decline who were recruited from health care facilities as well as through advertisements in the general population. Data analysis was conducted between January and March 2021.

Interventions  One hundred participants were randomly assigned (1:1 ratio) to 12 months of dietary supplementation with either a spermidine-rich dietary supplement extracted from wheat germ (0.9 mg spermidine/d) or placebo (microcrystalline cellulose). Eighty-nine participants (89%) successfully completed the trial intervention.

Main Outcomes and Measures  Primary outcome was change in memory performance from baseline to 12-month postintervention assessment (intention-to-treat analysis), operationalized by mnemonic discrimination performance assessed by the Mnemonic Similarity Task. Secondary outcomes included additional neuropsychological, behavioral, and physiological parameters. Safety was assessed in all participants and exploratory per-protocol, as well as subgroup, analyses were performed.

Results  A total of 100 participants (51 in the spermidine group and 49 in the placebo group) were included in the analysis (mean [SD] age, 69 [5] years; 49 female participants [49%]). Over 12 months, no significant changes were observed in mnemonic discrimination performance (between-group difference, −0.03; 95% CI, −0.11 to 0.05; P = .47) and secondary outcomes. Exploratory analyses indicated possible beneficial effects of the intervention on inflammation and verbal memory. Adverse events were balanced between groups.

Conclusions and Relevance  In this randomized clinical trial, longer-term spermidine supplementation in participants with subjective cognitive decline did not modify memory and biomarkers compared with placebo. Exploratory analyses indicated possible beneficial effects on verbal memory and inflammation that need to be validated in future studies at higher dosage.

Trial Registration  ClinicalTrials.gov Identifier: NCT03094546

중요성

노화 관련 기억력 저하 및 신경퇴행성 질환을 겪는 노인들을 대상으로 한 개입 전략 개발은

우리 세대가 직면한 가장 큰 과제 중 하나입니다.

스퍼미딘 보충은

동물 모델에서 뇌 및 인지 건강에 유익한 효과를 보여주었으며,

주관적 인지 저하를 겪는 개인에서 기억력 개선의 초기 증거가 보고되었습니다.

목적 이 위험군에서 장기적인 스페르미딘 보충이 기억력 성능과 생물학적 지표에 미치는 영향을 확인하는 것입니다.

연구 설계, 환경 및 참가자

이 12개월간 진행된 무작위 이중 맹검 위약 대조 2상 임상 시험(SmartAge 시험)은 2017년 1월부터 2020년 5월까지 진행되었습니다. 이 연구는 독일의 학술 임상 연구 센터에서 단일 센터 연구로 진행되었습니다.

대상자는 60세에서 90세 사이의 주관적 인지 기능 저하를 가진 개인으로,

의료 기관 및 일반 인구 대상 광고를 통해 모집되었습니다.

데이터 분석은 2021년 1월부터 3월까지 진행되었습니다.

개입

100명의 참가자가 무작위로 배정(1:1 비율)되어

12개월 동안 밀 배아에서 추출한 스페르미딘 풍부한 식이 보충제(0.9 mg 스페르미딘/일)

또는 위약(미세결정 셀룰로오스)을 복용했습니다.

89명(89%)의 참가자가 시험 개입을

성공적으로 완료했습니다.

주요 결과 및 측정 항목

주요 결과는 기저치에서 12개월 후 평가 시 기억력 성능의 변화(의도된 치료 분석)로, Mnemonic Similarity Task를 통해 측정된 기억력 구분 성능으로 평가되었습니다. 부차적 결과에는 추가적인 신경심리학적, 행동적, 생리학적 파라미터가 포함되었습니다. 안전성은 모든 참가자를 대상으로 평가되었으며, 프로토콜 준수 분석 및 하위 그룹 분석이 탐색적으로 수행되었습니다.

결과

분석에 포함된 참가자는

총 100명(스페르미딘 그룹 51명, 플라시보 그룹 49명)으로,

평균 연령은 69세(표준편차 5세)였으며 여성 참가자는 49명(49%)이었습니다.

12개월 동안 기억력 구분 성능(군 간 차이, −0.03; 95% 신뢰 구간, −0.11~0.05; P = 0.47) 및 부차적 결과에서 유의미한 변화는 관찰되지 않았습니다.

탐색적 분석은

개입이 염증 및 언어 기억에 대한 잠재적 유익한 효과를 시사했습니다.

부작용은 두 그룹 간 균형 있게 분포되었습니다.

결론 및 의미 이 무작위 임상 시험에서 주관적 인지 저하를 보이는 참가자에게 장기적인 스페르미딘 보충은 위약과 비교해 기억력과 생물학적 지표에 변화를 일으키지 않았습니다.

탐색적 분석은

언어 기억력과 염증에 대한 잠재적 유익한 효과를 보여주었으며,

이는 향후 더 높은 용량에서 추가 연구를 통해 검증되어야 합니다.

Introduction

Maintenance of cognitive function and brain health are of utmost importance in an aging society with an increase in age-related diseases, such as Alzheimer disease (AD). Cognitively healthy older individuals expressing a feeling of persistent cognitive deterioration (ie, subjective cognitive decline [SCD]) are believed to reflect the late preclinical stage of AD, accompanied by aberrant pathological brain changes as well as a higher risk of objective cognitive decline and clinical progression to symptomatic disease stages.1-5

Naturally occurring polyamines, particularly spermidine, are essential for multiple cellular processes, including autophagy and the maintenance of cellular homeostasis.6-9 A decrease of polyamine levels is associated with a decline of memory function in aged flies.9-11 A higher external supply of dietary polyamines restores endogenous spermidine levels in the brain of aging fruit flies, prevents age-related memory impairment,10,11 and has been shown to be able to pass the blood-brain barrier in middle-aged animal models.12,13 However, corresponding data in humans are still rare, including a pioneer study in healthy middle-aged male adults demonstrating an increase in blood polyamine levels after 2 months of enhanced dietary intake of polyamines.14 On that basis, we previously conducted a 3-month randomized, placebo-controlled, double-masked phase 2a study investigating spermidine supplementation in 30 older individuals with SCD. Excellent safety and tolerability as well as preliminary efficacy for improved memory performance in the spermidine-treated group were shown.15,16

To further validate the therapeutic potential of dietary spermidine against memory loss in older individuals at risk for AD and to identify possible neurophysiological mechanisms of action, we conducted a 12-month intervention trial in individuals with SCD. We hypothesized that spermidine supplementation (0.9 mg/d) would have a beneficial impact on memory performance, as well as on other neuropsychological, behavioral, and physiological parameters when compared with placebo.

서론

노화 사회에서 알츠하이머 병(AD)과 같은 연령 관련 질환의 증가로 인지 기능과 뇌 건강의 유지가 가장 중요합니다.

인지적으로 건강한 노인 중

지속적인 인지 저하를 느끼는 개인(즉, 주관적 인지 저하[SCD])은

AD의 후기 전임상 단계로 간주되며,

이상적인 병리학적 뇌 변화와 객관적 인지 저하 및 증상성 질환 단계로의 임상적 진행 위험이 높습니다.1-5

자연적으로 발생하는 폴리아민,

특히 스퍼미딘은 자가포식 및 세포의 항상성 유지 등

여러 세포 과정에 필수적인 물질입니다.6-9

폴리아민 수치의 감소는

노화된 파리에서 기억 기능 저하와 연관되어 있습니다.9-11

식이 폴리아민의 외부 공급 증가가

노화된 과일 파리의 뇌 내 내인성 스페르미딘 수치를 회복시키고

연령 관련 기억 장애를 예방하며,10,11

중년 동물 모델에서 혈액-뇌 장벽을 통과할 수 있음을 보여주었습니다.12,13

그러나

인간에서의 대응 데이터는 여전히 희귀하며,

건강한 중년 남성 성인에서 폴리아민 섭취를 강화한 후

2개월 만에 혈중 폴리아민 수치가 증가했다는 선구적인 연구가 포함됩니다.14

이를 바탕으로 우리는

SCD를 가진 30명의 노인 대상 3개월간 무작위, 위약 대조, 이중 맹검 2a상 연구를 수행했습니다.

스페르미딘 투여 그룹에서 우수한 안전성 및 내약성뿐만 아니라

기억력 개선에 대한 초기 효능이 확인되었습니다.15,16

알츠하이머 병 위험이 있는 노인에서

식이 스페르미딘의 기억력 감퇴에 대한 치료적 잠재성을 추가로 검증하고

가능한 신경생리학적 작용 메커니즘을 식별하기 위해,

우리는 SCD를 가진 개인을 대상으로 12개월 간 개입 연구를 수행했습니다.

우리는 스페르미딘 보충제(0.9 mg/일)가

위약 대비 기억력 성능뿐만 아니라

다른 신경심리학적, 행동적, 생리학적 지표에 유익한 영향을 미칠 것이라고 가설을 세웠습니다.

Methods

Study Design and Participants

The SmartAge study was a monocenter, randomized, double-masked, placebo-controlled phase 2b trial investigating the effect of 12-month dietary spermidine supplementation (through a spermidine-rich wheat germ extract) on memory performance and biomarkers in older individuals with SCD.17 The study was carried out at the NeuroCure Clinical Research Center, Charité–Universitätsmedizin Berlin, and the trial protocol was approved by the Ethics Committee of the Charité–Universitätsmedizin Berlin, Germany (Supplement 1). The study was in accordance with the Declaration of Helsinki and written informed consent was provided by all participants before starting the on-site screening. This study followed the Consolidated Standards of Reporting Trials (CONSORT) reporting guideline for randomized clinical trials.

Older individuals in the age range of 60 to 90 years were recruited from health care facilities and through advertisements in the general population. The main inclusion criterion was a diagnosis of SCD based on established guidelines.1 Eval‎uation of study eligibility was performed during study enrollment, including a telephone screening and an on-site screening. Baseline assessment encompassed neuropsychological testing, questionnaires, and a standardized medical examination. Following baseline assessment, participants were randomly assigned to spermidine-based supplementation (target intervention) or placebo supplementation (control intervention). A computer-based algorithm was used to generate a block-wise randomization sequence stratified by age and sex. Race and ethnicity data were not tracked in this study as there is no evidence that they might affect our outcomes. Participant allocation was carried out on a 1:1 basis by a study collaborator with no involvement in assessing outcomes. Participants in the verum group received a spermidine-rich dietary supplement extracted from wheat germ (The Longevity Labs). The daily dose of administered plant extract was 750 mg (corresponding to approximately 0.9 mg spermidine, 0.5 mg spermine, 0.2 mg putrescine, <0.004 mg cadaverine, and 0.12 mg L-ornithine) administered by 6 capsules of 125 mg each. As a comparator condition, the placebo group received 750 mg of microcrystalline cellulose. Baseline assessments were repeated after the 12-month intervention at a postintervention visit (Supplement 1; eMethods 1 in Supplement 2).

연구 설계 및 참가자

SmartAge 연구는 SCD를 가진 노인에서 12개월간의 식이 스페르미딘 보충제(스페르미딘 풍부한 밀 배아 추출물을 통해)가 기억력 성능 및 생물학적 지표에 미치는 영향을 조사한 단일 센터, 무작위, 이중 맹검, 위약 대조 제2상b 임상 시험입니다.17 이 연구는 베를린 샤리테 대학병원 신경치료 임상 연구 센터에서 진행되었으며, 연구 프로토콜은 독일 베를린 샤리테 대학병원 윤리위원회(보충 자료 1)에서 승인되었습니다. 이 연구는 헬싱키 선언에 부합하며, 모든 참가자는 현장 스크리닝 시작 전에 서면 동의서를 제출했습니다. 이 연구는 무작위 임상 시험 보고를 위한 통합 기준(CONSORT) 보고 지침을 준수했습니다.

60세에서 90세 사이의 노인들은 의료 시설과 일반 인구 대상 광고를 통해 모집되었습니다. 주요 포함 기준은 확립된 지침에 따라 SCD 진단을 받은 것이었습니다.1 연구 참여 자격 평가은 연구 등록 시 전화 스크리닝과 현장 스크리닝을 포함하여 진행되었습니다. 기저선 평가에는 신경심리학적 검사, 설문지, 표준화된 의료 검진이 포함되었습니다. 기저선 평가 후 참가자는 스페르미딘 기반 보충제 투여(목표 개입) 또는 플라시보 보충제 투여(대조군 개입)로 무작위 배정되었습니다. 연령과 성별에 따라 층화한 블록별 무작위 배정 순서는 컴퓨터 기반 알고리즘을 사용하여 생성되었습니다. 인종 및 민족 데이터는 본 연구에서 추적되지 않았으며, 이는 이러한 요인이 연구 결과에 영향을 미칠 수 있다는 증거가 없기 때문입니다. 참가자 배정은 결과 평가에 관여하지 않은 연구 협력자에 의해 1:1 비율로 진행되었습니다. 진실군 참가자는 밀 배아에서 추출한 스페르미딘 풍부한 식이 보충제(The Longevity Labs)를 투여받았습니다.

투여된 식물 추출물의 일일 용량은

750mg(스페르미딘 약 0.9mg, 스페르민 약 0.5mg, 푸트레신 약 0.2mg, 카다베린 <0.004mg, L-오르니틴 약 0.12mg)으로,

125mg씩 6캡슐로 투여되었습니다.

대조군으로는 위약 그룹이 미세결정 셀룰로오스 750mg을 투여받았습니다. 기저선 평가들은 12개월 간 개입 후 개입 후 방문 시 반복되었습니다(보충자료 1; 보충자료 2의 eMethods 1).

Outcomes

The primary outcome of this trial was the change in memory performance between baseline and the postintervention visit, operationalized by mnemonic discrimination performance assessed in the Mnemonic Similarity Task (MST).18 The mnemonic discrimination index was calculated from the responses during the recognition phase, similar to previous studies.16 ,19 Secondary outcomes included changes in neuropsychological parameters of different cognitive domains (verbal and visual-spatial memory, attention, executive functions, and sensorimotor speed), behavioral parameters of lifestyle, psychoaffective characterization as well as perceived quality of life, and physiological parameters comprising peripheral blood parameters (hematological parameters of safety, inflammation markers/cytokines, markers of vascular injury) and cardiovascular risk factors (vital signs, weight) between baseline and postintervention visit. Safety outcomes included the documentation of adverse events (AEs) and serious adverse events (SAEs) throughout the intervention period (eMethods 2 in Supplement 2).

Statistical Analyses

Analyses were performed according to the intention-to-treat principle. Missing data were imputed using multivariate imputation by chained equations based on 30 imputed data sets and predictive mean matching generated by the mice package in R version 4.0.3 (R Project for Statistical Computing).20 Primary and secondary outcomes were analyzed through covariance models with change in the outcome measure from baseline to 12-month postintervention visit as the dependent variable, intervention group as the factor, and the particular baseline measure (as well as age and sex) as covariates. In a second step, we conducted the same analyses in the prespecified per-protocol set, which included only those participants who successfully completed the 12-month intervention period (total, 89 participants; spermidine group, 42 participants; placebo group, 47 participants). In a third step, we repeated the same analyses (as the sensitivity analyses) for those participants who had successfully completed the 12-month intervention period with compliance rates above 90% (per-protocol plus set: total, 74 participants; spermidine group, 36 participants; placebo group, 38 participants). Safety outcomes (AEs and SAEs) were reported descriptively and analyzed using Poisson regression models, accounting for the different observation periods for each participant and allowing incidence rate and incidence rate ratios to be calculated with confidence intervals (in 100 person-years) in total and by intervention group. A 2-sided significance level of α = .05 was used. There was no correction for multiple testing, and no formal adjustment was made to the P values or CIs. The analyses were performed as described in the statistical analysis plan of the trial (eMethods 3 in Supplement 2).

Results

Study Participants

From January 31, 2017, through April 15, 2019, a total of 108 healthy older adults with SCD were enrolled in the SmartAge trial, of whom 100 participants (mean [SD] age, 69 [5] years; 49 women [49%] and 51 men [51%]) were randomly assigned to receive spermidine (51 participants) or placebo (49 participants) and consequently included in the intention-to-treat analysis (Figure 1). At baseline, both groups demonstrated comparable characteristics (Table 1). Follow-up data for 90 participants were available through May 2020. The median (IQR) follow-up period was 369 days (365.5-376.5 days) when considering only the 89 participants who successfully completed the trial intervention. Both groups showed high compliance rates, measured by the number of remaining capsules at postintervention assessment (mean [SD] compliance rate, 95.3% [7.7%]) (eAppendix 1 in Supplement 2).

Figure 1.  Study Flowchart

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AE indicates adverse event; SAE, serious adverse event; SCD, subjective cognitive decline. Per-protocol set included all participants completing the 12-month intervention (89 participants). Multiple imputation was performed for intention-to-treat analyses of full analysis set and per-protocol set.

Table 1.  Baseline Characteristics of the Participants Included in Intention-to-Treat Analysis

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CharacteristicParticipants, No. (%)Total (N = 100)Spermidine (n = 51)Placebo (n = 49)

Demographics
Sex
Women	49 (49.0)	24 (47.1)	25 (51.0)
Men	51 (51.0)	27 (52.9)	24 (49.0)
Age, mean (SD), y	69 (5)	69 (6)	69 (5)
Education, mean (SD), y	17 (3)	17 (4)	16 (3)
Family history
Dementia	29 (29.0)	13 (25.5)	16 (32.7)
AD	18 (18.0)	9 (17.6)	9 (18.4)
Oldfield hand preference, median (IQR), %	95 (85-100)	95 (90-100)	95 (80-100)
Neuropsychological, mean (SD)
MMSE, score	29.1 (0.9)	29.1 (1.0)	29.0 (0.9)
LMS delayed recall, score	24.3 (6.3)	24.2 (6.0)	24.5 (6.7)
TMT A, s	39.7 (12.4)	40.4 (12.0)	39.0 (13.0)
MWT, score	32.3 (2.6)	31.9 (3.0)	32.7 (2.0)
Behavioral, mean (SD)
Psychoaffective characterization
ECog-39, score	1.8 (0.4)	1.8 (0.5)	1.7 (0.3)
GDS, score	1.9 (1.6)	1.9 (1.7)	1.8 (1.5)
BFI-10, score
Extraversion	3.2 (1.0)	3.3 (1.0)	3.2 (0.9)
Agreement	3.3 (0.7)	3.3 (0.7)	3.3 (0.7)
Conscientiousness	3.9 (0.8)	4.0 (0.9)	3.9 (0.8)
Neuroticism	3.0 (1.0)	3.1 (1.0)	2.9 (0.9)
Openness	3.7 (1.0)	3.7 (1.0)	3.8 (0.9)
SVF-78, score
Positive	12.7 (2.6)	12.2 (2.7)	13.3 (2.5)
Negative	10.0 (4.1)	9.4 (4.3)	10.6 (3.9)
Lifestyle
LEQ, score	99.7 (21.6)	100.0 (23.0)	99.4 (20.4)
CAI, score	3.1 (0.5)	3.0 (0.5)	3.1 (0.4)
Energy intake, kcal/d	2375.4 (747.6)	2471.1 (709.7)	2275.7 (779.8)
MEDAS, score	6.4 (2.3)	6.6 (2.2)	6.3 (2.5)
Alcohol intake, g/d	11.5 (12.04)	10.6 (12.8)	12.3 (11.3)
Physiological
APOE ɛ4, positive
Heterozygous	22 (22.0)	7 (13.7)	15 (30.6)
Homozygous	2 (2.0)	2 (3.9)	0 (0.0)
Aβ statusa
Positive	7 (7.0)	3 (5.9)	4 (8.2)
Negative	23 (23.0)	12 (23.5)	11 (22.4)
Cardiovascular risk, mean (SD)
Blood pressure, mm Hg
Systolic	128.6 (16.2)	126.1 (17.0)	131.2 (15)
Diastolic	80.3 (9.3)	79.8 (10.9)	80.8 (7.4)
Heart rate, bpm	64.7 (9.7)	65.1 (11.3)	64.2 (7.6)
Weight, kg	75.4 (15.3)	76.3 (16.5)	74.4 (14.1)
BMI	26.0 (4.1)	26.3 (4.7)	25.7 (3.4)
Waist circumference, cm	95.5 (11.2)	96.0 (11.4)	94.9 (11.1)
Diabetes	8 (8.0)	5 (9.8)	3 (6.1)
Hypertension	42 (42.0)	23 (45.1)	19 (38.8)
Smoker
Current	5 (5.0)	4 (7.8)	1 (2.0)
Former	43 (43.0)	19 (37.3)	24 (49.0)

Efficacy Outcomes

Mnemonic discrimination performance was similar in both intervention groups at baseline (eTable 1 in Supplement 2). The adjusted mean change of mnemonic discrimination performance from baseline to postintervention assessment was −0.02 (95% CI, −0.08 to 0.04) in the spermidine group and 0.01 (95% CI, −0.04 to 0.06) in the placebo group, resulting in an adjusted treatment effect of −0.03 (95% CI, −0.11 to 0.05; P for primary efficacy outcome = .47) (Figures 2 and 3).

Figure 2.  Effect of Spermidine Supplementation on Mnemonic Discrimination (MD) Performance

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Notched box plots display within-group effects in MD performance in the spermidine group and the placebo group at baseline and postintervention assessments. Box plots include data of all participants who completed postintervention assessment. Notches in the shaded regions indicate 95% CI of the median, and shaded boxes the IQRs with lower (25th) and upper (75th) percentiles. Dots represent individual data points.

Figure 3.  Effect of Spermidine Supplementation on Primary and Selected Secondary Outcomes in Intention-to-Treat Analysis

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ALT indicates alanine aminotransferase; AST, aspartate aminotransferase; CRP, C-reactive protein; DBP, diastolic blood pressure; ECog-39, Everyday Cognition Scales (39 items); eGFR, estimated glomerular filtration rate; HDL, high-density lipoprotein; IFN-gamma, interferon gamma; INR, international normalized ratio of blood clotting; LDL, low-density lipoprotein; MST, Mnemonic Similarity Task; PSQI, Pittsburgh Sleep Quality Index; PSWQ, Penn State Worry Questionnaire; SBP, systolic blood pressure; SF-12, Short Form Health Survey; sICAM-1, soluble intercellular adhesion molecule-1; sVCAM-1, soluble vascular cell adhesion molecule-1; TMT, Trail Making Test; TNF-alpha, tumor necrosis factor alpha; VLMT, Verbaler Lern-und Merkfähigkeitstest, German version of the Rey Auditory Verbal Learning Test (AVLT); WHOQOL-BREF, World Health Organization Quality of Life. Missing data were imputed using multivariate imputation by chained equations (mice) based on 30 imputed data sets and predictive mean matching. Mean changes of each parameter from baseline to postintervention assessment with 95% CIs are presented for both intervention groups separately. Group differences and P values result from analysis of covariance models for change in outcome from baseline to postintervention visit, with the intervention group as the examined factor and adjusted for age, sex, and the particular baseline measure. Mean group differences in the forest plots were standardized by being converted into z scores. Forest plots and group differences were transformed, if necessary, to yield the same direction of effect.

Baseline data of secondary outcomes, including neuropsychological, behavioral, and physiological parameters, were similar for both intervention groups (Table 1; eTable 1 in Supplement 2). Statistical analyses of the full analysis set revealed no substantial treatment effect on any tested secondary parameter (Figure 3; eFigures 1 through 3 in Supplement 2).

Per-protocol analyses revealed no statistically significant intervention effects on mnemonic discrimination performance (−0.04; 95% CI, −0.10 to 0.03; P = .25) as well as on all secondary end points (eFigures 4-6 in Supplement 2). This pattern was also found in the per-protocol plus set for the analysis of an intervention effect on mnemonic discrimination performance (−0.04; 95% CI, −0.11 to 0.03; P = .28) (eFigure 7 in Supplement 2). However, between-group differences after the 12-month intervention were observed for soluble intercellular adhesion molecule-1 (sICAM-1) and Trail Making Test B (TMT B) (eFigures 7-9 in Supplement 2) in the per-protocol plus set. The adjusted mean change of sICAM-1 concentration in peripheral blood from baseline to 12-month postintervention assessment was −30.5 ng/mL (95% CI, −67.8 to 6.9 ng/mL) in the spermidine group and 25.7 ng/mL (95% CI, −11.2 to 62.7 ng/mL) in the placebo group, resulting in an adjusted intervention effect of −56.2 ng/mL (95% CI, −106.8 to −5.6 ng/mL; P = .03), demonstrating a possible beneficial effect of the intervention. The adjusted mean change of TMT B response time was 6.6 seconds (95% CI, −2.2 to 15.4 seconds) in the spermidine group and −7.3 seconds (95% CI, −15.9 to 1.3 seconds) in the placebo group, resulting in an adjusted intervention effect of 13.9 seconds (95% CI, 1.5 to 26.2 seconds; P = .03), demonstrating a negative effect of the intervention. No significant intervention effects were observed for any of the other parameters tested.

Exploratory prespecified subgroup analyses in the full analysis set showed no statistically significant differential intervention effects in subgroups. In the per-protocol set and per-protocol plus set, subgroup analyses showed effects of the intervention on memory performance and executive function/processing speed in individuals aged 70 years and older, in men, in individuals with higher baseline dietary spermidine intake, and in individuals with more severe subjective cognitive complaints, respectively (eAppendix 2 in Supplement 2).

Safety Outcomes

During the 12-month intervention time, 19 SAEs were documented among all participants, 7 in the spermidine group and 12 in the placebo group. All SAEs were rated as not related to the intervention and mild to severe in intensity. The incidence of SAEs regarding fatal or life-threatening events, hospitalization, or malignant and/or neoplastic processes was similar between groups (Table 2).

Table 2.  Serious Adverse Events During Spermidine or Placebo Supplementation

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CharacteristicParticipants by groupIRR (95% CI)P valueTotal (n = 100)Spermidine (n = 51)Placebo (n = 49)

Observation time, median (IQR), d	368 (365-376)	367 (364-372)	369 (365-380)	NA	NA
Total SAE
Participants, No.	19	7	12	NA	.30
IR per 100 PY (95% CI)	19.8 (12.2-30.0)	14.9 (6.4-28.8)	24.4 (13.1-40.9)	0.61 (0.23-1.52)
Fatal or life-threatening events
Participants, No.	1	1	0	NA	>.99
IR per 100 PY (95% CI)	1.0 (0.1-4.6)	2.1 (0.1-9.4)	NA	0
Acute hospital (inpatient hospital treatment or its extension)
Participants, No.	16	5	11	NA	.17
IR per 100 PY (95% CI)	16.6 (9.8-26.2)	10.7 (3.8-22.9)	22.4 (11.6-38.3)	0.48 (0.15-1.31)
Malignant/neoplastic processes
Participants, No.	2	1	1	NA	.97
IR per 100 PY (95% CI)	2.1 (0.3-6.4)	2.1 (0.1-9.4)	2.0 (0.1-8.9)	1.05 (0.04-26.49)

Overall, 129 AEs were recorded (spermidine group, 58 AEs; placebo group, 71 AEs) and the incidence in all system organ classes present in our cohort did not differ substantially between intervention groups (eTable 2 in Supplement 2). Noticeably, musculoskeletal and connective tissue was the only system organ class with substantially more AEs in the spermidine group (11 participants) compared with the placebo group (4 participants). The majority of AEs reported to this system organ class were age-related diseases and symptoms, such as osteoporosis, arthritis, gout attacks, and joint pain. Additionally, 1 participant in the spermidine group reported 2 AEs in that category (eAppendix 3 in Supplement 2).

Discussion

This phase 2b trial showed no effect following 12 months of spermidine supplementation on memory performance as assessed by mnemonic discrimination performance, as well as on any other neuropsychological, behavioral, or physiological parameter in intention-to-treat analyses compared with placebo. The amount and incidence rate ratios of AEs and SAEs were balanced between groups, and hematologic safety parameters showed no significant changes in either group, indicating excellent safety and tolerability of the spermidine intervention, a result reinforced by high compliance rates.

Consistent with the full analysis set, analyses of the per-protocol and the per-protocol plus set also revealed no effect of intervention on the primary outcome. This finding is not in line with our previous phase 2a study,16 where we found an improvement of mnemonic discrimination performance in the spermidine-treated group after 3-month supplementation in the same target group of participants, with a medium effect size. A 2020 study21 likewise provided evidence for an improvement of cognitive function after 3 months of higher spermidine intake through nourishment in older individuals with mild to moderate dementia. In addition, studies in aged model organisms also demonstrated improved memory function given a higher external supply of dietary spermidine.10,12,22,23 In rodent postmortem samples, polyamine concentration in the hippocampus was associated with age as well as with formation of memory, suggesting that maintenance and restoration of endogenous polyamine levels during aging could benefit memory function, especially in such a sensitive task as the one tested in our primary outcome.18,19,24-26

The absence of an intervention effect of this clinical phase 2b study on spermidine supplementation might be due to a combination of several factors. First, the daily dose of 0.9 mg spermidine might not have been sufficient to achieve strong effects on memory function and biomarkers in cognitively healthy older individuals. The amount of additional daily spermidine intake via capsules corresponds to about 10% of the average spermidine intake per day in developed countries.27 The decision to use a lower range dosage was based on previous reports of higher polyamine levels in some malignant neoplasms and a positive regulatory effect of polyamines on cell growth.28 In addition, our preclinical study in mice provided evidence for an increase of relative kidney weight after spermidine supplementation at high dosage.15 In our preliminary study, we therefore used a dosage of 750 mg wheat germ extract that was well below the levels at which adverse effects would be observed in mice to assess safety and first efficacy in humans. This dosage was maintained in the present phase 2b trial but might not have been sufficient to induce cognitive benefits. In line with our phase 2a study, blood polyamine levels were also not altered after 12-month intervention. However, blood polyamine levels might not necessarily be an indicator of higher dietary polyamine intake, as polyamines are likely rapidly taken up by solid tissues from blood after absorption from the intestinal lumen.27,29 This assumption is supported by a 2021 study30 that failed to detect increased spermidine levels in the blood after a 12-month intake of spermidine-enriched natto (a traditional Japanese product), corresponding to an increase of about 14 mg spermidine per day.

Second, individuals with SCD were chosen as a target group to eval‎uate the target intervention in an early stage of AD, when cognitive function was still preserved, as recommended by landmark publications in the field.1,31 However, supplementation with dietary spermidine might not act as a memory booster, but rather prevent age-related memory impairment and development of AD, a possibility supported by evidence from animal studies.10 Given that our target group comprised cognitively healthy older individuals with SCD, only subtle cognitive decline was to be expected,2 and in fact, we found no significant decline in memory function after 12 months in the placebo-treated group. Thus, to observe a significant difference between groups, a boost in memory performance in the target group would have been necessary, which might not be in the scope of this supplementation regimen. Future trials should include patients with more advanced stages of AD, such as those experiencing mild cognitive impairment, in whom decline in cognitive function over the study period is to be expected.32

논의

이 2b상 임상시험에서, 12개월간의 스페르미딘 보충이 기억력 성능(기억력 구분 성능으로 평가)에 대한 효과를 보여주지 않았으며, 의도된 치료 분석에서 위약과 비교했을 때 신경심리학적, 행동적, 또는 생리학적 매개변수에서도 유의미한 차이를 보이지 않았습니다. 부작용(AE) 및 중대한 부작용(SAE)의 발생률과 발생 빈도 비율은 두 그룹 간 균형을 보였으며, 혈액학적 안전성 지표는 두 그룹 모두에서 유의미한 변화가 관찰되지 않았습니다. 이는 스페르미딘 투여의 우수한 안전성과 내약성을 나타내며, 높은 복용 순응률로 이 결과가 강화되었습니다.

전체 분석 집합과 일치하게, 프로토콜 준수 집합 및 프로토콜 준수 플러스 집합 분석에서도 주요 결과에 대한 투여 효과는 관찰되지 않았습니다. 이 결과는 우리 이전 2a상 연구16와 일치하지 않습니다.

해당 연구에서는 동일한 대상 그룹에서

3개월간의 스페르미딘 보충 후 기억력 구분 성능이 개선되었으며,

중간 효과 크기를 보였습니다.

2020년 연구21 역시 경도에서 중등도 치매를 가진 노인에서

영양을 통해 스페르미딘 섭취량을 증가시킨 후

3개월 후 인지 기능 개선을 입증했습니다.

또한 노화 모델 유기체 연구에서도 식이 스페르미딘의 외부 공급량이 증가할 경우 기억 기능이 개선되었다는 결과가 보고되었습니다.10,12,22,23 설치류 사후 조직 샘플에서 해마의 폴리아민 농도는 연령 및 기억 형성과 연관되어 있었으며, 이는 노화 과정에서 내인성 폴리아민 수치의 유지 및 회복이 기억 기능에 유익할 수 있음을 시사합니다. 특히 우리 연구의 주요 결과와 같은 민감한 과제에서 더욱 그렇습니다.18,19,24-26

이 임상 2b상 연구에서 스페르미딘 보충제의 개입 효과가 관찰되지 않은 것은 여러 요인의 조합 때문일 수 있습니다.

첫째,

인지 기능이 건강한 노인에서 기억 기능과 생물학적 지표에 강한 효과를 달성하기에는

일일 0.9mg의 스페르미딘 용량이 충분하지 않았을 수 있습니다.

캡슐을 통해 추가로 섭취한 스페르미딘의 양은

선진국에서 하루 평균 스페르미딘 섭취량의 약 10%에 해당합니다.27

낮은 용량 범위를 선택한 이유는

일부 악성 종양에서 폴리아민 수치가 높다는 이전 보고와

폴리아민이 세포 성장에 대한 긍정적인 조절 효과를 보였기 때문입니다.28

또한, 우리 연구팀의 전임상 연구에서 고용량 스페르미딘 보충 후 상대적 신장 무게 증가가 관찰되었습니다.15 따라서 본 연구에서는 인간에서의 안전성과 초기 효능을 평가하기 위해 마우스에서 부작용이 관찰되는 수준보다 훨씬 낮은 750mg 밀 배아 추출물 용량을 사용했습니다. 이 용량은 현재 진행 중인 2b상 임상시험에서도 유지되었지만 인지 개선 효과를 유발하기에는 충분하지 않았을 수 있습니다.

2a상 연구와 일치하게,

12개월 간 개입 후 혈중 폴리아민 수치는 변화하지 않았습니다.

그러나

혈중 폴리아민 수치는

식이 폴리아민 섭취량이 높다는 지표가 아닐 수 있습니다.

폴리아민은 장 점막에서 흡수된 후

혈액에서 고체 조직으로 빠르게 흡수되기 때문입니다.27,29

이 가정은 2021년 연구30에서 스퍼미딘 강화 나토(전통적인 일본 제품)를 12개월간 섭취한 후

혈중 스퍼미딘 수치가 증가하지 않았다는 결과로 뒷받침됩니다.

이는 하루 약 14mg의 스퍼미딘 증가에 해당합니다.

둘째,

SCD를 가진 개인을 대상 그룹으로 선택한 이유는

알츠하이머 병의 초기 단계에서 인지 기능이 여전히 유지된 시점에서 목표 개입을 평가하기 위함입니다.

이는 해당 분야의 주요 연구에서 권장된 바와 같습니다.1,31

그러나

식이 스페르미딘 보충은 기억력 향상제로 작용하기보다는

노화 관련 기억력 저하와 알츠하이머 병 발병을 예방하는 역할을 할 수 있으며,

이는 동물 연구 결과로 뒷받침됩니다.10

우리 대상 그룹은

인지 기능이 건강한 노인으로 SCD를 가진 개인으로 구성되었기 때문에,

인지 기능의 미묘한 저하만 예상되었습니다.2

실제로,

위약 투여 그룹에서 12개월 후 기억 기능의 유의미한 저하는 관찰되지 않았습니다.

따라서 그룹 간 유의미한 차이를 관찰하려면 대상 그룹에서 기억 성능의 향상이 필요했을 것이나, 이는 이 보충 요법의 범위 내에 포함되지 않을 수 있습니다. 향후 연구에서는 경도 인지 장애를 겪는 등 AD의 더 진행된 단계에 있는 환자를 포함해야 하며, 이 경우 연구 기간 동안 인지 기능 저하가 예상됩니다.32

Apart from a large number of well-described positive effects, there is also evidence of detrimental effects of polyamines, such as potential enhancement of tumor growth, increase of relative kidney weight, or modulation of neuronal excitability.15,28,33 In our clinical trial, we demonstrated excellent safety and tolerability of 12-month spermidine supplementation, indicated by comparable amounts and severity of AEs and SAEs without any evidence of newly developed tumors or seizures, inconspicuous kidney parameters, and high compliance to the intervention. However, patients with previously diagnosed malignant neoplasms were excluded, so the impact of spermidine supplementation on tumor growth could not be eval‎uated in this trial.

Exploratory per-protocol plus analyses provided evidence of a possible beneficial effect of spermidine supplementation on sICAM-1 blood plasma level, a parameter of blood vessel injury and inflammation that is elevated in endothelial dysfunction, inflammatory processes, aging, and dementia.34,35 Thus, downregulation of sICAM-1 levels through higher external supply of spermidine might indicate anti-inflammatory and vascular-protective effects, which in turn would contribute to the preservation of higher-order brain functions.8,36 Of note, we also observed a slight decrease in TMT B response time, a neuropsychological test assessing executive function and processing speed, which has been shown to be affected by aging and also in SCD.37,38 Thus, a decrease in TMT B performance induced by higher spermidine intake might indicate an impairment of white matter microstructure, which in turn is associated with poorer executive function, processing speed, and task-switching.39,40 However, other neuropsychological tests in this domain do not support this finding, nor does the positive evidence for anti-inflammatory effects of spermidine support a detrimental effect on white matter integrity, so this finding needs to be validated or refuted in future trials. Subgroup analyses in the per-protocol and per-protocol plus sets provided some indication for a possible beneficial effect of spermidine supplementation on memory performance in individuals aged 70 years and older, in men, and in individuals with more severe subjective cognitive concerns, respectively. However, all exploratory findings would not be statistically significant after correction for multiple testing. Thus, these exploratory analyses need to be interpreted with caution but might serve as starting points or useful for generating hypotheses to be tested in future intervention trials.

폴리아민의 긍정적인 효과 외에도, 종양 성장 촉진, 상대적 신장 무게 증가, 신경 세포 흥분성 조절 등 유해한 효과에 대한 증거도 존재합니다.15,28,33 본 임상 시험에서 12개월간의 스페르미딘 보충 요법은 우수한 안전성과 내약성을 보여주었습니다. 이는 부작용(AE) 및 심각한 부작용(SAE)의 발생 빈도와 심각도가 유사했으며, 신규 종양 발생이나 발작의 증거가 없었으며, 신장 파라미터가 정상 범위 내에 있었고, 치료 준수율이 높았기 때문입니다. 그러나 이전에 악성 종양 진단을 받은 환자는 제외되었기 때문에, 본 연구에서는 스페르미딘 보충 요법이 종양 성장에 미치는 영향을 평가할 수 없었습니다.

탐색적 프로토콜 준수 분석은 스페르미딘 보충이 혈관 손상 및 염증의 지표인 sICAM-1 혈장 수치에 유익한 효과를 가질 수 있음을 시사했습니다. sICAM-1은 내피 기능 장애, 염증 과정, 노화, 치매와 연관되어 증가합니다.34,35 따라서 스페르미딘의 외부 공급 증가를 통해 sICAM-1 수치가 감소하는 것은 항염증 및 혈관 보호 효과를 나타낼 수 있으며, 이는 다시 고차원 뇌 기능의 유지에 기여할 수 있습니다.8,36 주목할 점은, 우리는 TMT B 반응 시간(노화와 SCD에서 영향을 받는 것으로 알려진 실행 기능 및 처리 속도를 평가하는 신경심리학적 검사)이 약간 감소했다는 점을 관찰했습니다.37,38 따라서 스페르미딘 섭취 증가로 인한 TMT B 성능 감소는 백질 미세구조 손상을 나타낼 수 있으며, 이는 다시 실행 기능, 처리 속도, 작업 전환 능력 저하와 연관될 수 있습니다.39,40 그러나 이 분야에서의 다른 신경심리학적 검사 결과는 이 결과를 지지하지 않으며, 스페르미딘의 항염증 효과에 대한 긍정적인 증거도 백질 무결성에 대한 유해한 영향을 지지하지 않습니다. 따라서 이 결과는 향후 연구에서 검증되거나 반박되어야 합니다. 프로토콜 준수 그룹과 프로토콜 준수 및 추가 분석 세트에서의 하위 그룹 분석은 각각 70세 이상 개인, 남성, 주관적 인지 문제 정도가 더 심각한 개인에서 스페르미딘 보충이 기억력 성능에 긍정적인 영향을 미칠 수 있다는 일부 단서를 제공했습니다. 그러나 모든 탐색적 결과는 다중 비교 교정 후 통계적으로 유의미하지 않았습니다. 따라서 이러한 탐색적 분석은 신중하게 해석되어야 하지만, 향후 개입 임상시험에서 테스트할 가설을 수립하는 출발점이나 유용한 자료로 활용될 수 있습니다.

Limitations

Several limitations should be considered when interpreting our findings. First, biomarkers for AD (amyloid, tau, phosphorylated tau) were not required for study participation, and cerebral amyloid-β status was available from only 30% of participants. Thus, negative findings in this trial might be due to a potentially large percentage of individuals without amyloid or tau pathology, indicating other reasons for worrying about their cognitive function that might be less susceptible to dietary approaches.2,6 However, our participants with SCD were characterized according to currently accepted guidelines for SCD,1 and our intervention did not specifically target amyloid or tau. Second, we chose an intervention period of 12 months, which might have been too short to observe significant changes in cognition and biomarkers. However, other supplement trials were similar in length, and an intervention of only 3 months had previously shown beneficial effects.16,41 Nevertheless, longer intervention periods might induce stronger effects and might allow for assessing effects of spermidine supplementation on naturally occurring cognitive decline in older adults.

Conclusions

Supplementation with spermidine that increased daily supply by about 10% did not result in a beneficial effect on memory function or other neuropsychological, behavioral, or physiological parameters. Positive results from per-protocol and subgroup analyses regarding memory function and anti-inflammatory actions, combined with the excellent safety profile of the supplementation, endorse future trials with higher dosage to further investigate spermidine as a mean to delay cognitive decline in individuals at risk for AD.