What is BDNF?

BDNF stands for Brain-Derived Neurotrophic Factor. BDNF is a protein found in the brain and in the spinal cord. BDNF helps with the survival of neurons (nerve cells) and the development of new ones. BDNF also helps neurons to make synapses, which are communication connections.

The gene that provides instructions to the body for making this protein is called the BDNF gene.

What does BDNF do?

The precise effects of BDNF are not all known, but are likely specific to the different types of neurons it acts on. BDNF is thought to be involved in:

• Learning
• Formation of memories
• The "reward center" of the brain
• Control of hunger and the feeling of satiety (the feeling of being "full" after eating) 

Weight and Satiety

Individuals with WAGR syndrome who are overweight/obese, especially those who have gained weight early in life, are more likely to have the BDNF gene deletion. This suggests that the lack of BDNF might be playing a role in eating habits and metabolism, because BDNF should signal the brain that the stomach is full and the body has obtained enough energy. But if BDNF levels are too low, these signals never reach the brain. This may be why some people with WAGR and BDNF deletion do not seem to experience feeling full after eating. This lack of satiety may cause them to eat extremely large amounts of food, to eat rapidly, to constantly “seek” food, and to eat whatever they can find, including spoiled foods or garbage.

Learning and Social Behavior

Individuals with WAGR syndrome and BDNF gene deletion score lower in tests of intelligence and adaptive behavior and higher in tests of social impairment than individuals without the deletion.

Reduced Pain Sensitivity

Studies in both animals and humans suggest that BDNF plays a role in nociception, or the perception of pain. People with WAGR syndrome and BDNF deletion may have an increased tolerance for pain. In some cases, they may not react as expected (grimace, cry, or complain) with minor or even with moderate injury or illness.

Diet

Individuals with WAGR syndrome and BDNF gene deletion benefit from referral to a dietician

• The purpose for this referral is to assess the person's dietary habits to identify areas that could be improved
• Parents and professionals should be aware that limiting calories may not be as effective for weight loss in these patients as in those without BDNF gene deletion
• A dietician may recommend modifying the environment to limit the person's access to food, such as developing a food schedule, locking the refrigerator and kitchen cabinets, and placing food waste out of reach

Safety

Since people with WAGR syndrome and BDNF gene deletion have an increased tolerance for pain and decreased expression of pain, parents and physicians should be alert to other signs of injury or illness

• A child with a broken bone may not appear to be in pain, but may simply not use the arm or may refuse to walk
• A person with pancreatitis may have nausea and vomiting but not display the signs of abdominal pain that are typical with this illness

Exercise

Studies have shown that regular exercise leads to the release of proteins and other molecules from muscle, fat, and liver tissue that can affect levels of BDNF. While there are currently no studies on the effects of exercise in patients with BDNF gene deletion, regular exercise in typical people has been shown to help with anxiety and depression, and with learning and memory formation.

Education

Children with WAGR syndrome and BDNF gene deletion benefit from Early Intervention Services and Special Education. Particular emphasis on maximizing communication and social skills may also be helpful.