Seroquel (quetiapine) is an antipsychotic medication marketed by AstraZeneca for the treatment of schizophrenia and bipolar disorder. It is also used along with antidepressants to treat depression.

In Huntington’s disease, Seroquel has been shown to improve behavioral symptoms and may decrease chorea, uncontrollable and involuntary dance-like movements, a hallmark of the disease.

How Seroquel works

Seroquel works through two mechanisms. The first is by acting on dopamine receptors. Dopamine is a signaling molecule in the brain that plays an important role in motor control and thinking abilities. In Huntington’s disease patients, dopamine levels are imbalanced. In the early and intermediate stages of the disease, dopamine’s activity is too high, which is thought to cause chorea. Seroquel binds to dopamine receptors, preventing dopamine itself from binding to its receptor, thereby interfering with its function.

The second mechanism through which Seroquel acts is by blocking serotonin receptors, primarily one called 5HT2A. Inappropriate binding of serotonin, another signaling molecule in the brain, to the 5HT2A receptor plays a role in psychiatric disorders, such as schizophrenia, dyskinesia (difficulties with voluntary movements), and depression.

It is not entirely understood how the combination of these two mechanisms results in the therapeutic effects of Seroquel in Huntington’s disease patients.

Seroquel in clinical trials

Seroquel has not been tested in clinical trials for Huntington’s disease. However, two case reports suggest that the medication might benefit Huntington’s disease patients.

The first report describes the case of a 30-year-old woman, who had chorea, and difficulties with walking, oral function, and fine motor tasks. She had received Haldol (haloperidol), Zyprexa (olanzapine), and Xenazine (tetrabenazine) in the past. Each medication had only temporarily improved her symptoms.

She was then treated with Seroquel, initially at a dose of 100 mg per day, which was rapidly increased to 600 mg per day. Within one week, her chorea, walking, and motor difficulties improved. Soon after, her ability to move her eyes and mouth also improved. She was even able to perform daily activities on her own, such as grocery shopping and cooking.

The second case report described five patients with a variety of symptoms, such as chorea, walking difficulties, agitation and aggressive behavior, psychosis, depression, and dementia. All patients had previously received other antipsychotic medications without sustained improvement of their symptoms.

The patients received 150 to 600 mg of Seroquel per day. Their behavioral symptoms, including psychosis, agitation, irritability, and insomnia, improved, but their chorea and motor function remained unchanged.

Additional information

Patients should tell their doctor if their mood or behavior changes, and if they develop anxiety, panic attacks, or become depressed while taking Seroquel.

Common side effects of Seroquel include dizziness, weakness, trouble with movement, increased appetite and weight gain, dry mouth, sore throat, nausea, and vomiting.

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