Anesthesia and ADHD - The Unseen Link

Introduction

The neurotoxin (chemicals that directly or indirectly cause harm to the central nervous system) agents in general anesthesia can negatively affect a child's brain. It can have a toll on the child’s cognition, learning, and behavior. The neuronal growth, differentiation, and synaptogenesis (the formation of new connections between new neurons in the brain or the nervous system) in the developing brain can be impaired as a result. This article unveils how a child’s brain can be influenced by anesthesia.

What Is ADHD?

ADHD (Attention-deficit hyperactivity disorder) is one of the most common disorders that affects brain development and neurological functions. Research shows that people with the condition have some differences in their brain functions, nerve networks, and neurotransmitters (chemicals that help in communication between neurons). It is a long-term condition that affects a person’s ability to manage their emotions, thoughts, and actions.

What Are the Symptoms of ADHD?

The common symptoms of children with ADHD include difficulty in:

• Managing their behavior.

• Giving attention for long periods.

• Regulate their mood.

• Control their hyperactivity.

• Stay organized.

• Follow directions.

• Sit in a place quietly.

• Sustaining focus on tasks.

• Act without thinking.

• Difficulty to maintain self-control.

• Wish for immediate rewards.

• Restless.

• Talk too much.

• Remain in constant motion, be it running, climbing, or fidgeting.

Can Anesthesia Cause ADHD?

Much research done to find the link between general anesthesia and ADHD has given varied results. Many studies show anesthesia-induced neuronal damage and neuronal toxicity in the developing brain when anesthesia is given from the third stage of gestation (the period during which a fetus develops in the womb) to three years of life in human beings. These changes in the brain were due to the suppression of the neuronal synapses, leading to apoptosis (programmed cell death). The negative impairments on the hippocampus and frontal cortex can cause memory and behavioral problems. Several studies in animals have discovered ADHD-like changes following an anesthetic exposure. Seven-day-old rats were chosen for these experiments, as synaptogenesis is rapid and very sensitive to external factors like anesthetic agents.

How Does Anesthesia Cause ADHD?

Many studies done on animals have shown that anesthetic agents can cause ADHD-like symptoms, especially in developing brains. Some of the schools of thought on why or how this occurs include:

• Dopamine Receptor: Studies show that the disruption of the dopamine pathway can affect the proper functioning of the brain. This is seen following an exposure of the developing brains to the chemicals in the anesthetic agents. The neurons for dopamine are found in the frontal and temporal lobes. The activity of the anesthetic agents causes a delay in their development when compared to the other non-dopamine neurons. As a result, they mature only in adulthood. Damage to these dopamine neurons is found to exacerbate the symptoms of ADHD. Exposure of the developing brain to these anesthetic chemicals can even cause alterations in the genes that are important for the growth and differentiation of these dopamine neurons.

• N-Methyl-D-Aspartic Acid Receptor: Studies also show that the glutamatergic system (one of the major excitatory neuron pathways in the nervous system) has a role in causing ADHD following exposure to general anesthesia. The anesthetic agents can disrupt the glutamatergic pathways in an immature brain, leading to ADHD-like symptoms.

• Brain-Derived Neurotrophic Factor: Brain-derived neurotrophic factor plays an important role in the regulation of synaptogenesis. This factor is found to be widely distributed in the brain, especially in the hippocampus and the cerebral cortex region. Exposure to anesthetic agents can cause a decrease in the number of brain-derived neurotrophic factors, leading to ADHD.

• Prefrontal Cortex: Disorders caused by structural and functional disruptions can cause ADHD. A series of feedback from the prefrontal cortex and the basal ganglia plays an important role in regulating motor and emotional functions. The prefrontal cortex is also involved in behavior and higher cognitive functions like decision-making. Studies show that anesthesia having ketamine interrupts the transfer of information between the cortical areas. Prenatal anesthesia containing ketamine has been shown to cause dysplasia (the formation of abnormal cells) and neuronal loss in the prefrontal cortex. This can be a cause of ADHD following anesthesia. Studies in rats showed hyperactivity following exposure to Propofol, an anesthetic agent. Hence, ADHD can be caused in small children exposed to anesthesia during their early years as there is an interference with the proper growth and development of neurons in the prefrontal cortex.

• Synaptogenesis: Normally, the functioning of the brain is regulated by the formation of new synapses (connections between two neurons), and their efficiency in passing information. The formation of new synapses is thought to begin in the third stage of pregnancy and reaches its peak in the third year of life. Exposure to general anesthesia can alter this. Exposure to general anesthesia in children less than three years reduces the formation of new synapses, resulting in symptoms like ADHD. The formation of abnormal synaptogenesis can also cause ADHD-like symptoms, as the excitatory and inhibitory pathways (pathways in the brain responsible for behavioral and cognitive functions) are inhibited.

• Neural Projections: People with ADHD are found to have reduced cortical, subcortical, and total cerebral volumes. This area is responsible for higher-level functions like language and decision-making. In addition, the area of the brain responsible for motor processing is also damaged in ADHD. Administering anesthesia in small children can hamper the maturation and development of the cortical and subcortical parts of the brain, resulting in ADHD-like symptoms. Disruptions in the connections between the parts of the brain, like the prefrontal cortex and basal ganglia, are also noticed. This can result in cognitive, learning, and behavioral deficits in these children.

Conclusion

The exposure of small children to general anesthesia is a concerning factor for both the parents and the healthcare professionals. This is mainly due to the neurodegenerative changes it can cause in the developing brains. The U.S. Food and Drug Administration (FDA) has warned about the potential damage that could be caused by exposing children younger than three years to long and repeated use of anesthesia. Exposing the developing brains can cause neuronal damage and developmental neurotoxicity. Hence, healthcare professionals must be cautious while exposing young children and infants to anesthesia.