Millions of US birth records uncover an autism risk surge tied to common drugs taken during pregnancy
Prenatal exposure to medications that inhibit sterol biosynthesis, including certain antidepressants, antipsychotics, beta-blockers, and statins, is associated with a significantly increased risk of autism spectrum disorder in offspring, with risk rising in a dose-dependent manner. The proportion of pregnancies with such exposure increased from 4.3% in 2014 to 16.8% in 2023.
A landmark study by researchers and published in Molecular Psychiatry has identified a significant association between prenatal prescription of commonly utilized medications and the risk of autism spectrum disorder (ASD) in children
Analyzing 6.14 million maternal-child health records from the Epic Cosmos database—representing nearly one-third of all U.S. births between 2014 and 2023—the team found that prescription of medications known to inhibit the cholesterol synthesis pathway were consistently associated with higher rates of ASD in offspring.
These sterol biosynthesis–inhibiting medications (SBIMs) include certain antidepressants, antipsychotics, anxiolytics, beta-blockers and statins. These are the generic names of the 14 medications studied: aripiprazole, atorvastatin, bupropion, buspirone, fluoxetine, haloperidol, metoprolol, nebivolol, pravastatin, propranolol, rosuvastatin, sertraline, simvastatin and trazodone. Many of these are among the most commonly prescribed medications.
Cholesterol is essential for fetal development, especially for the brain, the most cholesterol-rich organ. The fetal brain begins producing its own sterols around 19–20 weeks of gestation. Genetic disruptions in this pathway are known to cause severe developmental syndromes such as Smith-Lemli-Opitz syndrome (SLOS), in which up to 75% of children meet criteria for ASD. Many widely used medications can unintentionally interfere with this pathway.
The study authors stress that no pregnant patient should discontinue or alter medication without medical supervision, as many SBIMs are essential, often life-saving treatments. Instead, the study calls for a re-evaluation of prescribing practices and for developing safer alternatives for use during pregnancy.
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Eric S. Peeples et al, Sterol pathway disruption in pregnancy: a link to autism, Molecular Psychiatry (2026). DOI: 10.1038/s41380-026-03610-7

The brain replays past emotional experiences during sleep

Neuroscientists have been trying for several years to uncover the neural processes that allow humans and various other animals to recall emotional experiences of past events. Past studies have identified a network of brain regions that support the encoding and consolidation of these memories. These regions include the hippocampus and the amygdala, as well as the para-hippocampal, perirhinal, prefrontal, parietal and retrosplenial cortices.

Researchers at Neuroscience NeuroSU and the Institute of Biology Paris-Seine- IBPS carried out a study on rats aimed at better understanding how the dorsal and ventral hippocampus, two segments of the hippocampus known to have different functions, contribute to the consolidation of emotional memories of past events.

Their findings, published in Nature Neuroscience, suggest that these two regions coordinate during sleep to consolidate memories of past experiences and the emotions associated with them.

We already knew a lot about the role of sleep-dependent reactivation in the dorsal hippocampus, but comparatively much less is known about the ventral part of the hippocampus.

 It was previously shown that the dorsal part of the hippocampus communicates during sleep with other structures related to emotions, like the amygdala. However, the anatomy shows that the dorsal hippocampus is not connected to these structures.

Earlier neuroscience studies found that the dorsal hippocampus is not connected to other brain regions associated with the processing of emotions. This suggests that it communicates with these regions via an intermediate brain region when consolidating emotional memories of past events.

Researchers now hypothesized that this intermediate region is the ventral hippocampus, the other segment of the hippocampus. Contrarily to the dorsal hippocampus, this region is known to communicate with emotion-processing brain regions.

To test their hypothesis, the researchers carried out a series of experiments involving freely moving rats. These rats had tiny electrodes implanted in their brains, which recorded the activity of many neurons simultaneously both in the dorsal and ventral hippocampus.

They collected electrophysiological recordings while the rats were undergoing an emotional experience, and then sleeping.

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They then used computational methods to analyze the activity of these neurons and examine how they coordinate/dialogue during sleep, and how accurately this coordination reflects the preceding emotional experience."

While they were awake, some rats experienced a small electric shock, while others received a reward. The researchers looked at the activity of neurons in the dorsal and ventral hippocampus both during these experiences and after them, while the rats were sleeping.
The researchers observed neural reactivation (a phenomenon known to support sleep-dependent memory-processing) during sleep that spans the entire axis of the hippocampus following an emotional positive or negative experience.
The recordings collected by this research team confirmed that while rats are sleeping, their brain consolidates memories of emotional experiences they had while awake. The consolidation of both aversive and pleasurable experiences appears to be supported by coordinated activity between the dorsal and ventral hippocampus.
They also found that reactivation is more faithful to the original experience when the experience was negative.
This might explain the bias towards better memories of negative compared to positive events. More broadly, it identifies a mechanism that allows us to form memories combining context and emotions, positive or negative.

If validated in humans, the results of this recent study could help to shed more light on the intricate neural processes that support the consolidation of traumatic memories and could play a role in trauma-related mental health conditions. For instance, they might improve the understanding of post-traumatic stress disorder (PTSD) and other mental health disorders that are linked to intrusive and sometimes debilitating memories of traumatic events.

Juan Facundo Morici et al, Dorsoventral hippocampus neural assemblies reactivate during sleep following an aversive experience, Nature Neuroscience (2026). DOI: 10.1038/s41593-026-02252-w.

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