The brain depends on an intricate internal recycling system to keep its exceptionally long-lived cells functioning. A new review in Nature Neuroscience examines how macroautophagy, commonly known as autophagy, helps neurons and glial cells maintain their health, adapt to stress and remove damaged cellular components. The process is increasingly linked to conditions ranging from neurodevelopmental disorders to Alzheimer’s and Parkinson’s diseases, as well as psychiatric illnesses. By bringing together findings from developing and mature nervous systems, the review presents autophagy not as a single emergency response, but as a continuously operating network that supports brain function throughout life.
Autophagy is a lysosome-dependent degradation pathway. During the process, portions of the cytoplasm, defective proteins and damaged organelles are enclosed within double-membraned structures called autophagosomes. These vesicles then undergo a series of trafficking and maturation steps before fusing with lysosomes, acidic organelles containing enzymes that break down the cargo. The resulting amino acids, fatty acids and other molecular building blocks can be released back into the cell for reuse. This combination of disposal and recycling is particularly important in neurons, which can survive for decades without being replaced and must maintain axons that extend over considerable distances.
The review emphasizes that autophagy operates in close coordination with other membrane-trafficking systems rather than functioning as an isolated pathway. Autophagosomes must be generated at appropriate locations, transported through the neuron and delivered to lysosomes with precise timing. Their movement relies on the cell’s cytoskeletal tracks and motor proteins, while endosomes, lysosomes and secretory compartments contribute to the processing and exchange of cargo. Regulatory pathways involving nutrient and energy sensors, including mTOR and AMP-activated protein kinase, adjust autophagy according to cellular conditions. This allows cells to increase recycling during nutrient shortage, energetic stress or the accumulation of damaged material, while preventing unnecessary degradation when resources are plentiful.
Neurons present unusual challenges for quality control because their cell bodies, dendrites and axons may be separated by large distances. Autophagic structures can form near synapses and in axon terminals, where local damage or intense activity creates an immediate demand for clearance. They can also be transported toward the soma, where lysosomal degradation is often more efficient. This movement is not merely housekeeping. Autophagy influences the composition of synapses, the availability of signaling proteins and the ability of neurons to respond to stimulation. By removing selected components, the pathway can help remodel neural connections during development, learning and adaptation.
During brain development, autophagy contributes to the maturation and survival of neural cells. Developing neurons must extend processes, establish synaptic contacts and eliminate structures that are no longer required. Autophagy intersects with apoptosis, metabolism and membrane trafficking to help determine whether cells adapt, differentiate or die. The pathway also affects the function of glial cells, including astrocytes and microglia, which support neurons, regulate the extracellular environment and participate in immune surveillance. In these cells, autophagy can influence inflammatory responses, energy management and the handling of cellular debris, making it relevant to communication between neurons and their supporting networks.
Genetic evidence has established the importance of this system in human brain biology. Variants in genes involved in autophagosome formation, lysosomal function, vesicle transport and related quality-control processes can cause Mendelian disorders that primarily affect the nervous system. Such conditions may present with developmental delay, intellectual disability, seizures, movement abnormalities, muscle weakness or progressive neurodegeneration. The wide range of clinical outcomes reflects the complexity of the pathway: a defect in cargo recognition may have different consequences from a failure of lysosomal acidification or a disruption of axonal transport. Together, these disorders demonstrate that even partial impairment of autophagy can become damaging in cells with high metabolic demands and limited regenerative capacity.
The review also connects autophagy dysfunction with common neurodegenerative diseases. When autophagy or lysosomal degradation is inefficient, proteins prone to misfolding may accumulate, damaged mitochondria may persist and inflammatory signals may intensify. Mitochondria are especially important targets because they produce energy but can generate harmful reactive oxygen species when defective. Selective autophagy of mitochondria, known as mitophagy, helps remove these organelles before they compromise the cell. In aging neurons, however, the production, transport or degradation of autophagic cargo may become less efficient. This creates a potential feedback loop in which damaged organelles and protein aggregates further disrupt trafficking and energy metabolism.
Autophagy is not always beneficial in every context, and the review highlights the importance of understanding its timing and location. Increasing autophagy indiscriminately could degrade components that cells still need, while blocking the pathway may cause undegraded cargo to accumulate. The effects can also differ among cell types and disease stages. A temporary increase in autophagy during stress might be protective, whereas chronic activation associated with persistent damage could reflect a failing system rather than successful repair. These distinctions complicate the development of treatments designed to manipulate the autophagy–lysosome network. Potential strategies include adjusting pathway regulators, improving lysosomal function, correcting trafficking defects or targeting selective forms of autophagy rather than stimulating the entire process.
Researchers are also exploring whether autophagy-related molecules could serve as biomarkers of neurological disease. Changes in lysosomal proteins, autophagic cargo, mitochondrial quality-control signals or extracellular vesicles may provide clues about cellular stress before extensive neuronal loss occurs. However, measurements from blood or cerebrospinal fluid may not directly represent events inside specific brain regions, and a rise in an autophagy marker does not necessarily prove that degradation has been completed. The field therefore needs more precise assays that distinguish autophagy initiation from productive autophagic flux, the full journey from cargo capture to lysosomal breakdown. Such tools could improve diagnosis, track disease progression and reveal whether a treatment is restoring cellular recycling rather than simply altering one molecular indicator.
The central message of the review is that brain health depends on a distributed and adaptable quality-control system operating across neurons, glia, synapses and organelles. Autophagy helps preserve cellular materials, regulate neural connectivity and respond to metabolic and environmental challenges, but its effectiveness depends on coordinated membrane traffic and lysosomal competence. As scientists clarify how this network changes with age and disease, therapies aimed at the autophagy–lysosome pathway may become more precise. The challenge will be to restore the right form of recycling in the right cell, at the right stage, without disturbing the essential balance that allows the brain to renew its components while preserving its complex architecture.
Subject of Research: Autophagy and autophagy–lysosome pathways in brain homeostasis, neuronal function and neurological disease
Article Title: Roles of autophagy in brain homeostasis and disease
Article References: Kim, H., Wickstead, E.S., Zhou, X. et al. Roles of autophagy in brain homeostasis and disease. Nature Neuroscience (2026). https://doi.org/10.1038/s41593-026-02426-6
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41593-026-02426-6
Keywords: autophagy, macroautophagy, lysosomes, neurons, glial cells, brain homeostasis, neurodevelopmental disorders, neurodegeneration, psychiatric disorders, biomarkers, neuronal quality control
Tags: Alzheimer’s diseasebrain healthcellular recycling in the braindamaged organelles removalglial cell functionlong-lived neuron maintenancelysosome-dependent degradationneurodegenerative diseasesNeurodevelopmental Disordersneuronal autophagyParkinson’s diseasestress adaptation in neurons
