The Auditory world of Premature Infants: A Critical Window

The delicate auditory system of premature infants is particularly vulnerable to the harsh environment of neonatal intensive care units (NICUs). Professor Olivier Baud, a leading neonatologist, highlighted at the Autism and Music Symposium on March 7th, the intricate link between music, neuroprotection, and autism, suggesting a coherent explanation for the neurological basis connecting music and autism. His research underscores the importance of understanding how early auditory experiences shape brain development, especially in preterm babies.

With advancements in neonatal care, infants as young as 24 weeks of gestation can now survive, a stage when their cochlear function is already active. The inner ear’s development begins as early as 15 weeks. However, the transition from the womb to the NICU presents a stark contrast in auditory experiences.

From Womb to NICU: An Auditory Shock

The intrauterine environment provides a nurturing soundscape for the developing fetus. Sounds are muffled, rhythmic, and primarily consist of the mother’s heartbeat and the musical qualities of her voice. This contrasts sharply with the NICU,which Professor Baud describes as a brutal shock.

NICUs are often filled with unpredictable and aggressive noises,with sound levels frequently exceeding 45 decibels and peaking at 60 dB due to equipment like fans and CPAP machines. The World Health Association (WHO) recommends a maximum environmental noise exposure of 40 dB at night to protect vulnerable populations, including children. The constant barrage of noise, coupled with the separation from the mother’s voice, can disrupt the hormonal balance in premature infants, favoring stress hormones like cortisol over neuroprotective hormones like oxytocin.

Music as a Neuroprotective Agent

Beyond auditory function, prematurity can also impact the development of brain regions responsible for memory and emotional processing. Oxytocin, a hormone crucial for neuroprotection, plays a vital role in these processes. Imbalances in oxytocin levels can negatively effect behavioral functions.

Research indicates that music can positively influence the connectivity of the salience network, a central hub for neural networks involved in socio-emotional development, including the Default Mode Network (DMN), which governs concentration, behavioral control, and cognition.Music promotes early brain maturation, increasing cortical complexity in regions crucial for socioemotional development, which are often compromised in premature infants. Studies have also shown that music can increase the volume of brain tonsils, bringing it closer to that of full-term infants.

Furthermore, preclinical studies on mice suggest that stimulating neuronal oxytocin production can positively influence microglia reactivity and brain development, offering another avenue for exploration in human studies.

music therapy: A Growing Field in Autism Treatment

The World Health Organization (WHO) has recognized the positive impact of arts on physical health, social relations, and well-being. Music therapy, in particular, has garnered increasing attention as a potential intervention for autism spectrum disorder (ASD). According to the CDC, approximately 1 in 36 children in the United States are diagnosed with ASD as of 2023, highlighting the need for effective therapeutic approaches.

Functional MRI (fMRI) studies have demonstrated that music therapy can increase social communication scores and auditory-motor connectivity in individuals with autism after 8 to 12 weeks of sessions. Othre studies have observed a decrease in alpha-amylase levels, a marker of anxiety, after just one session.

A 2022 Cochrane meta-analysis concluded that music therapy shows short- and medium-term benefits for individuals with autism. Musical interventions were associated with overall improvement compared to standard care or placebo therapy, and contributed to a reduction in the severity of symptoms. However, conducting rigorous clinical trials in this field remains challenging, particularly due to the difficulty of implementing double-blind studies.

music can certainly have a therapeutic effect.But the use of the term music therapy presents risks: it is not demonstrated therapy in a controlled manner.

Professor Philippe Evrard, neuropediatrician