Mood Disorders in AADC Deficiency

Brian Murphy, Ph.D. avatar

by Brian Murphy, Ph.D. |

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Aromatic L-amino acid decarboxylase (AADC) deficiency is a rare genetic disorder that involves a decrease in several neurotransmitters — chemicals that send messages to and from nerve cells — such as dopamine and serotonin. These neurotransmitters play an important role in mood and emotions.

What are mood disorders?

Mood disorders are a broad term for conditions that affect a person’s emotional state, including depression, bipolar disorder, and seasonal affective disorder (SAD). These disorders may show up as instances where your emotions don’t match what is happening around you. Some examples are being sad, irritable, or very happy for no reason. People with mood disorders also may have just a neutral emotional state, without getting very happy or very sad about anything in their lives.

How does AADC deficiency relate to mood?

Researchers have described mood disorders in AADC deficiency patients, with manifestations that may range from irritability to mood swings, and excessive crying. Sometimes patients with AADC deficiency have dysphoria, or generalized feelings of dissatisfaction, unhappiness, or irritability.

Mutations in the DDC gene cause AADC deficiency, which results in the production of fewer functional AADC enzymes. The AADC enzyme is involved in a crucial step in the production of both dopamine and serotonin. Therefore, when functional AADC isn’t present in high enough levels, it reduces the amounts of these neurotransmitters.

Low levels of serotonin may lead to depression. Dopamine is often considered the “happy hormone” and is related to feelings of pleasure. Reductions in both of these molecules in AADC deficiency can lead to the dysphoric or depressed moods.


It is important to speak to a physician about long-lasting bouts of mood disorders. Your doctors may be able to prescribe medication or therapy to help. For example, psychotherapy, or talk therapy, can be beneficial for patients with depression or other mood disorders.

Treatments for AADC deficiency such as monoamine oxidase inhibitors (MAOIs) or selective serotonin reuptake inhibitors (SSRIs) also may improve mood disorders.

Patients with feelings of hopelessness and severe depression should seek immediate assistance from an organization such as the National Suicide Prevention Lifeline, for people who live in the U.S., or the International Association for Suicide Prevention (IASP), for those living in Europe.


Last updated: Sept. 16, 2020


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