The human brain, with its 86 billion neurons and an unparalleled density of connections, is a masterpiece of biological sophistication. Yet this remarkable architecture is also vulnerable. Autism, epilepsy, depression, schizophrenia: these are conditions associated with subtle disruptions in brain connectivity—where each functional imbalance can become a potential target for intervention.
Advances in brain imaging, genomics, and neural network modeling now make it possible to map these dysfunctions with unprecedented precision. Hyperconnectivity in brain networks in autism, excitation/inhibition imbalance in epilepsy, desynchronization of emotional circuits in depression etc., these are mechanisms that can now be quantified, opening the door to new therapeutic avenues.
For the pharmaceutical industry, the challenge is now clear: turn this complexity into actionable biomarkers and develop approaches—whether technological or molecular—capable of intervening with precision on targeted circuits. In this article, Alcimed explores how connectivity imbalances are becoming strategic levers for innovation in neurology and neuropsychiatry.
The clinical potential of therapeutic approaches targeting brain connectivity is already reflected in strong market momentum. Deep Brain Stimulation (DBS) represented a USD 1.61 billion market in 2025 (Precedence Research, 2024), while Transcranial Magnetic Stimulation (TMS) revenues reached USD 806 million, with annual growth rates exceeding 10%1Coherent Market Insights, 2025. More than 244,000 patients have already received a DBS implant across all indications2Sandoval-Pistorius, S. S., Hacker, M. L., Waters, A. C., Wang, J., Provenza, N. R., De Hemptinne, C., Johnson, K. A., Morrison, M. A., & Cernera, S. (2023). Advances in Deep Brain Stimulation : From Mechanisms to Applications. Journal Of Neuroscience, 43(45), 7575‑7586. https://doi.org/10.1523/jneurosci.1427-23.2023.
In parallel, pharmacological approaches exploring the effects of psychedelic substances constitute a market estimated at USD 2.2 billion in 2024, projected to reach nearly USD 9 billion by 20343InsightAce Analytic, 2025. Some of these molecules act through mechanisms of neuronal plasticity, directly modulating the connectivity of networks involved in neuropsychiatric conditions.
To understand how these therapeutic strategies can target specific circuits, it is essential to revisit what makes the human brain both exceptional and fragile. The human brain stands out among species due to the richness and density of its neuronal connections. The expansion of the cerebral cortex—a key region for higher cognitive functions such as language, memory, perception, and consciousness—is a major factor. In humans, this layer is particularly thick and contains nearly 16 billion neurons, twice as many as in chimpanzees and more than ten times as many as in macaques4Sousa et al., 2017. The human cortex also contains a higher proportion of glial cells—astrocytes, oligodendrocytes, and microglia—which provide metabolic support, enable myelination, and regulate neuronal activity (for more on the role of glial cells, see our dedicated article!). Their functional role, long underestimated, is now recognized as central to network balance and plasticity.
Beyond sheer numbers, the structure of human neurons further reinforces this complexity: denser arborizations, more numerous connections, and therefore the ability to process larger volumes of information more rapidly. These features contribute to the high cognitive performance of our species.
Finally, this complexity results from an atypical development of neuronal connectivity in humans during childhood: slower, more prolonged, and more conducive to the emergence of sophisticated networks. This extended development supports the formation of more diverse and adaptable circuits, but also makes them more sensitive to disruptions, particularly during critical periods of neurodevelopment.
This remarkable architecture, which enables advanced mental functions, also creates a landscape where vulnerabilities are revealed by neuropsychiatric disorders.
What if neuropsychiatric disorders were not solely defined by observable symptoms, but instead reflected measurable dysfunctions in neuronal networks? Across disorders such as autism, schizophrenia, epilepsy, and depression, research highlights specific imbalances between brain networks—often detectable from childhood and sometimes measurable down to the molecular level. These alterations become functional markers—and potentially therapeutic targets.
Far from being merely a localized focus of abnormal activity, epilepsy is now understood as a disorder of brain networks. The imbalance between excitation and inhibition lies at the core of the condition, particularly within thalamo-cortical circuits, where insufficient inhibition enables the emergence of synchronized neuronal hyperactivity.
At the molecular level, several dysfunctions contribute to this hyperexcitability by affecting the systems that normally regulate neuronal activity. Key mechanisms include the overactivation of glutamate receptors (AMPA, NMDA), deficits in GABAergic interneurons, ion channel dysfunctions, and neuroinflammation.
Autism is characterized by a distinct brain organization in which connectivity between regions does not follow typical developmental patterns. Large-scale functional imaging reveals hypoconnectivity in sensory and attentional circuits, alongside hyperconnectivity of the default mode network (DMN)—the network active at rest—with other cortical and subcortical regions. These imbalances are directly correlated with the severity of social and cognitive symptoms. From early childhood, a reduction in the density of physical connections between regions can be detected, suggesting that these alterations are established very early in development.
These observations position connectivity as a central biomarker of autism and potentially as a lever for targeted intervention on affected networks. For instance, repetitive transcranial magnetic stimulation (rTMS) is being tested for its therapeutic effect on long-range connectivity reorganization in individuals with autism specter disorder (ASD).5Yang et al., 2023 Other interventions, such as neurofeedback, demonstrated in a clinical trial involving ASD children the potential to regulate connectivity and temporal variability in specific brain regions, although further validation of these results is required.6Kang et al., 2025 It should be noted, however, that these neurobiological approaches do not replace individualized psychological and educational support, which remains a cornerstone of effective care pathways.
Psychiatric disorders such as depression and schizophrenia are often associated with specific disruptions in brain networks. For instance, studies have shown desynchronization between the insula and the prefrontal cortex in depression7Morriss et al., 2024, as well as hyperconnectivity of the default mode network in schizophrenia8Sasabayashi et al., 2023, which may contribute to the intrusion of internal thoughts.
These findings help better characterize the diversity of patient profiles in neuropsychiatric conditions and support the idea that certain patient subtypes may benefit from more targeted approaches. As with autism, these biological markers are meaningful only if their measurement is integrated into a comprehensive care strategy that considers the patient’s life trajectory and includes long-term psychological support.
Neurostimulation approaches offer concrete therapeutic opportunities to modulate brain connectivity in a targeted manner.
These results may explain the growing interest in personalized strategies based on mapping altered networks, enabling the design of more targeted, better-tolerated, and more effective interventions.
Some molecules under development aim to modulate brain connectivity through mechanisms of neuronal plasticity. While their effects remain variable, several results are promising.
These approaches illustrate the potential of neuroplastic interventions to target specific functional networks. Their effectiveness may, however, depend on improved patient stratification based on connectivity profiles, biological markers, or developmental trajectories. More personalized trial designs could therefore help fully unlock their therapeutic potential.
A detailed understanding of brain connectivity opens up new avenues to understand, characterize, and treat neurological and psychiatric disorders. It moves beyond symptom-based approaches by identifying functional signatures specific to each condition—and potentially to each patient. This shift toward a “network-based” understanding of the brain is transforming the standards of therapeutic development.
In this context, healthcare industry stakeholders have a key role to play: integrating these insights to refine patient selection criteria, stratify clinical trial populations based on neurofunctional profiles, and develop personalized therapies. At Alcimed, we support you in integrating these advances into your R&D roadmaps, identifying the most promising targets, and adapting your therapeutic development strategies to the new standards of precision medicine. Do not hesitate to contact our team.
About the author,
Joseph, Consultant in Alcimed’s Healthcare team in France
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