Blood Lipid Signature Reveals Hidden Metabolic Clues in ALS

A new study has uncovered a striking pattern of lipid dysregulation in the blood of patients with amyotrophic lateral sclerosis, revealing that the plasma lipidome is profoundly reshaped in this fatal neurodegenerative disorder and that inherited genetic predisposition to life-course adiposity may interact with these metabolic alterations. The research, conducted at Peking University Third Hospital, provides one of the most comprehensive quantitative portraits yet of circulating lipid perturbations in ALS and opens fresh avenues for understanding how body composition and fat metabolism contribute to disease pathogenesis. By combining ultraperformance liquid chromatography–tandem mass spectrometry lipidomic profiling with polygenic risk scores for birth weight, body fat percentage, appendicular lean mass and whole-body fat-free mass, the investigators have built a foundational framework that links systemic metabolic handling to one of medicine’s most devastating conditions.

Amyotrophic lateral sclerosis is characterized by the progressive loss of motor neurons, leading to muscle weakness, respiratory failure and death, typically within a few years of symptom onset. Yet beyond its neurological hallmark, ALS has long been recognized as a disease with profound systemic metabolic dimensions. Patients frequently experience declining body mass index, disrupted energy homeostasis, hypermetabolism and dysregulated lipid metabolism. Body mass index and adiposity have been proposed to modify ALS risk and predict survival, while fat mass, body fat percentage and fat-free mass have been explored as prognostic factors. Lipid dysregulation is also a well-known feature of motor neuron diseases more broadly, having been genetically and potentially causally linked to disease risk through Mendelian randomization studies. Circulating lipid and metabolomic profiles have additionally been associated with ALS prognosis, suggesting that these metabolic signatures may carry both diagnostic and prognostic information.

Despite this accumulating evidence, a critical question remained unanswered: whether genetic predisposition to adiposity interacts with the lipidome to influence ALS pathogenesis, and if so, how inherited adiposity risk shapes lipid metabolism in the context of the disease. This gap has fundamentally limited understanding of the roles that adipose tissue and lipid metabolism play in ALS, thereby hindering the development of targeted therapies. To address this, the research team prospectively enrolled sporadic ALS patients meeting revised El Escorial criteria within two years of symptom onset, along with sex- and age-matched neurologically healthy controls recruited from the same institution’s health examination centre. Blood samples were collected in K2EDTA tubes after overnight fasting, centrifuged within two hours and stored at minus eighty degrees Celsius until lipidomic analysis. The investigators were blinded to sample allocation during lipid profiling, and all participants provided written informed consent under ethical approval from the hospital’s Institutional Review Board.

Quantitative lipidomic profiling was performed using an ExionLC ad UPLC system coupled to a QTRAP 6500+ mass spectrometry system, with metabolite identification against a proprietary database covering more than four thousand lipid species. Quality control measures included pooled quality control samples injected at regular intervals, internal standards for quantification and rigorous data preprocessing demonstrating excellent technical reproducibility. Mass spectrometry data were acquired in both positive and negative ionization modes using multiple reaction monitoring for targeted lipids. A total of eight hundred ninety lipid species were detected across one hundred eighty-two plasma samples, spanning seven major classes: forty carnitines, twenty-five fatty acids, sixty-nine sphingolipids, four hundred one glycerophospholipids, three hundred twenty-seven glycerides, twenty-seven sterol lipids and one prenol lipid. Following standard DNA extraction, single nucleotide polymorphism genotyping was conducted on a MassARRAY MALDI-TOF system, and beta-weighted polygenic risk scores were calculated for the four life-course adiposity traits using published genome-wide association study data at specified p-value thresholds.

The results revealed a distinct profile of circulating lipid dysregulation in ALS, with seventy-eight lipid species showing statistically significant, large-effect alterations between patients and controls after adjustment for age, sex and body mass index. Among these, medium- and long-chain acylcarnitines exhibited the most marked depletion, with thirty of forty detected species, representing seventy-five percent of this class, significantly lower in ALS patients. Acylcarnitines participate in mitochondrial fatty acid transport and therefore provide an indirect window into systemic fatty acid handling. Their uniform depletion suggests a broad disruption of carnitine-associated metabolism in ALS, a finding supported by accumulating evidence linking carnitine-related pathways to the disease. A recent Mendelian randomization study testing the causal effects of approximately one thousand plasma metabolites on ALS observed protective effects for carnitine derivatives, while longitudinal metabolomics evidence indicates that carnitine metabolism correlates with disease severity and progression. An earlier cross-sectional study also showed that lower serum levels of L-carnitine were associated with higher ALS severity.

Beyond acylcarnitines, the study identified coordinated alterations across multiple lipid classes. Among sphingolipids, four species were significantly lower in ALS patients, including sphingosine and several sphingomyelins, while three ceramide species were elevated. Among glycerophospholipids, lysophosphatidylcholines were the most prominently affected, with twenty-two of thirty-five species uniformly depleted. Seven phospholipid compounds were significantly up-regulated, including specific phosphatidylcholines and phosphatidic acids. Furthermore, seven specific triglycerides were consistently elevated, and two fatty acids were up-regulated. No significant differences were observed among sterol or prenol lipids. The sphingomyelin–ceramide axis is closely involved in membrane homeostasis, inflammatory signalling and cellular stress, and genetic evidence supports its relevance to ALS: pathogenic SPTLC1 variants causing juvenile ALS lead to dysregulated de novo sphingolipid synthesis. The pattern observed in this sporadic ALS cohort, with increased ceramides and reduced sphingomyelins, differs from the excessive sphingolipid synthesis seen in SPTLC1-associated juvenile disease and may reflect distinct mechanisms of sphingolipid remodelling.

To evaluate the diagnostic potential of these metabolic alterations, the researchers constructed machine learning–based candidate models using the seventy-eight significant differential lipids. Comparing logistic regression, random forest and support vector machines under stratified fivefold cross-validation, they identified a parsimonious fixed panel comprising three acylcarnitines: carnitine C12:0, carnitine C10:0 and carnitine C18:2. This three-feature panel yielded an area under the receiver operating characteristic curve of 0.977 under standard cross-validation. In a more conservative procedure where recursive feature elimination was repeated within each training fold and evaluation was restricted to the held-out fold, the pooled out-of-fold AUC was 0.958, with a mean fold AUC of 0.959 plus or minus 0.050. This attenuation from the original estimate is consistent with reduced feature-selection optimism. However, the analysis remains internal to a single-centre cohort, and the initial seventy-eight candidate lipids were identified using the full dataset, meaning residual optimism and cohort-specific effects cannot be excluded. The model should therefore be regarded as an exploratory candidate biomarker rather than a clinically ready diagnostic tool, requiring independent multicentre validation with harmonized quantitative assays and clinically relevant ALS-mimic controls.

The study then explored whether life-course adiposity polygenic risk scores were associated with plasma lipid levels and whether these associations differed between ALS patients and controls. After false discovery rate correction, no direct associations between any polygenic risk score and individual lipids remained significant. However, in exploratory analyses examining risk score–by–disease status interactions, sixteen lipid species showed nominally significant interaction effects. These comprised thirteen acylcarnitines, one sphingomyelin, one phosphatidylcholine and one triacylglycerol. Critically, acylcarnitines were significantly enriched among these sixteen nominal signals compared with the background set of seventy-eight ALS-associated lipids, yielding an odds ratio of 11.47 with a corrected p value of 6.52 times ten to the minus four. This class-level enrichment suggests that the nominal signals were not randomly distributed across lipid classes and provides hypothesis-generating support for a potential interplay between adiposity-related genetic background and carnitine-associated metabolic variation in ALS. The finding that adiposity risk scores, especially those for body fat percentage and birth weight, differentially modulate carnitine levels in patients versus controls suggests that an individual’s genetic background for fat storage may influence the severity or presentation of the underlying bioenergetic deficit in ALS.

When the interaction analysis was extended to all eight hundred ninety detected lipid species, nominally significant interaction signals were identified for one hundred eighty-five lipid species, with differing lipid-class distributions across adiposity traits. Lipids interacting with the birth weight risk score were predominantly glycerophospholipids and sphingolipids, while those interacting with the body fat percentage score were primarily glycerides and glycerophospholipids. Lipids associated with the appendicular lean mass score were overwhelmingly glycerophosphospholipids, and interactions for the whole-body fat-free mass score were mainly composed of glycerides. However, none of these individual interactions survived multiple-testing correction, and the displayed lipid-class distributions should not be interpreted as statistically confirmed pathway enrichment. A mediation analysis designed to assess whether any of the eight hundred ninety quantified blood lipids mediated the relationship between adiposity risk scores and ALS risk yielded null findings, likely constrained by the limited sample size available, as mediation studies typically require larger cohorts to achieve sufficient statistical power.

The concomitant elevation of selected triglycerides may be compatible with broader remodelling of systemic lipid utilization and storage in ALS. A complementary neuroendocrine mechanism has recently been proposed linking mutation-specific lipid abnormalities and altered systemic ANGPTL-3/4 signalling to hypothalamic dysfunction and neuroinflammation. Through regulation of lipoprotein lipase, the ANGPTL system may influence triglyceride hydrolysis and lipid partitioning across peripheral tissues, although the relevance of this pathway to the current findings remains hypothesis-generating since ANGPTL proteins and lipoprotein-lipase activity were not directly assessed. Several limitations warrant acknowledgment. The diagnostic classifier was evaluated only by internal cross-validation, which assessed reproducibility rather than external generalizability. The relatively modest sample size limited statistical power for mediation and interaction analyses. Plasma lipidomics may not directly reflect central nervous system metabolism, and the responsible tissue compartments cannot be determined from circulating measurements alone. ALS patients and controls also differed in sampling time and fasting duration, and metabolic comorbidities, dyslipidaemia and lipid-lowering medication use were not prespecified exclusion criteria. Despite these constraints, the comprehensive quantitative characterization of the plasma lipidome in a well-defined cohort, combined with the integration of life-course adiposity polygenic risk scores, provides convergent evidence that systemic lipid metabolic dysregulation is an important component of ALS pathophysiology and merits further investigation of its diagnostic and therapeutic relevance.

Subject of Research: Plasma Lipidome Is Dysregulated in Amyotrophic Lateral Sclerosis and Associated With Life‐Course Adiposity Polygenic Risk

Article Title: Plasma Lipidome Is Dysregulated in Amyotrophic Lateral Sclerosis and Associated With Life‐Course Adiposity Polygenic Risk

Article References: Zhang, L., Zhang, L., Zheng, Y., Zhuang, Z., Tang, L., Zheng, W., Xia, K., Ye, S., Yin, T., Huang, T., & Fan, D. (2026). Plasma Lipidome Is Dysregulated in Amyotrophic Lateral Sclerosis and Associated With Life‐Course Adiposity Polygenic Risk. Journal of Cachexia, Sarcopenia and Muscle, 17(5), Article e70410. https://doi.org/10.1002/jcsm.70410

Image Credits: AI Generated

DOI: 10.1002/jcsm.70410

Keywords: Plasma, Lipidome, Dysregulated, Amyotrophic, Lateral, Sclerosis, Associated, Life, Course, Adiposity, Polygenic, Risk