Featured in Science Digest #161

A low-dose nutrient blend restored key social behaviors in mouse models of autism. Digest

doi.org
2 min read •

Autism spectrum disorder (ASD) involves difficulties with social interaction and communication, but evidence on whether and how supplements might support treatment remains limited. Researchers in Taiwan tested whether a mixture of dietary nutrients could improve brain function and behavior in mouse models of autism.

The team studied male mice that carried a mutation in one of three autism-associated genes (Tbr1, Nf1, or Cttnbp2) along with littermates without the corresponding mutation. Some mice received a nutrient blend from the juvenile stage until they reached adulthood and completed the study's behavioral experiments, while others received the blend only during adulthood for a single week. In additional tests, each nutrient was also given on its own. The blend combined three nutrients: zinc, L-serine, and a mix of the branched-chain amino acids (BCAAs) leucine, isoleucine, and valine.

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The nutrients improved several abnormalities in behavior and brain function:

  • In mouse models of autism that received the nutrient blend for one week, several groups of brain proteins increased, including those that help nerve cells communicate with each other and manage their metabolism. Together, these changes made the overall protein pattern look more similar to that of mice without the mutation.
  • The blend also lowered excessive activity of nerve cells in a brain region important for social behavior and made the cells' firing patterns look more normal during social encounters.
  • Zinc, serine, or BCAAs alone did not change social behavior, whereas the blend improved social interaction with other mice.
  • The long-term group did not undergo protein analysis or brain-activity imaging and was tested on a broader behavioral battery than the one-week group. They showed improved performance on a basic learning and memory task, spent more time interacting with another mouse and showed a stronger preference for social contact over an object, but their movement and anxiety-like measures stayed the same.

These findings suggest that the nutrient blend works, at least in part, by supporting the function and activity of synapses, the tiny contact points between nerve cells where signals are passed from one cell to receptors on another. Zinc helps organize the protein structures that anchor receptors and it also influences the activity and function of receptors that respond to the chemical messenger glutamate. L-serine can be converted inside the brain into D-serine, a molecule that helps those same receptors work properly. The BCAAs support the production of new proteins inside nerve cells and activate a growth-related pathway known as mTOR, which helps cells adjust their structure and function.

Much more work is needed before any conclusions can be drawn for patients with ASD. Nevertheless, the study suggests that adjusting nutrient levels could become one way to support brain circuits that are disrupted in certain forms of autism. In this clip, Dr. Jed Fahey describes the beneficial effects of sulforaphane in modulating the symptoms of autism and other brain disorders.