Pharmacogenetic Testing Can Improve Anxiety Treatment

Anxiety disorders are one of the most common psychiatric disorders in the nation. According to the Anxiety and Depression Association of America, approximately 40 million adults in the United States have some form of anxiety disorder¹. While many different psychiatric medications have been developed to help patients with anxiety, it can be challenging to find an effective medication regimen that minimizes adverse effects and maximizes therapeutic benefits. Finding an optimal treatment plan often requires a lot of trial and error with various medication formulations and dosages, adding to patient frustration and distrust of medications.

One way that providers can reduce the amount of trial and error when prescribing medications and improve medication compliance is by utilizing pharmacogenetic (PGx) testing. PGx testing is the practice of examining a particular patient’s DNA to determine how they would respond to certain medication(s). While there is growing evidence that PGx testing can predict medication efficacy², new research also shows that PGx testing can help clinicians determine proper medication dosages by eliminating medications that could lead to unpleasant side effects based on an individual’s genetic makeup³.

The Genetic Basis

Upon ingesting a medication, the human body begins to naturally break it down into smaller chemical substances in a process known as drug metabolization. Studies have shown that a group of liver enzymes called Cytochrome P450 (CYPs) conduct about 90% of drug metabolization⁴. Knowing how these enzymes function allows us to better understand how they might metabolize different medications.

Your DNA contains instructions for creating various CYP enzymes. Differences in DNA lead to differences in enzymatic function. When researchers conduct pharmacogenetic testing, they primarily look for genetic variations to determine the rate at which a drug is metabolized in your body affects its concentration in the bloodstream. This, in turn, affects your body’s reaction to this particular drug.

Scientists have classified CYP enzymes primarily into three different categories:

1. Rapid metabolizer:If an enzyme is a rapid metabolizer, that means it can break down medications very quickly. If the drug is metabolized too quickly, your body isn’t exposed to enough of it, thereby the drug won’t be as effective⁵.
2. Slow metabolizer: A slow metabolizer, on the other hand, breaks down medications very slowly. As a result, drugs metabolized by these enzymes might remain in the body for a longer time before they are fully broken down, leading to adverse side effects.
3. Extensive metabolizer: An extensive metabolizer breaks down medications at what is considered a ‘normal’ rate. Ideally, physicians should consider choosing drugs that fall in this category due to normal enzymatic activity.

Genes and Anxiety Medication

Many of the drugs used to treat anxiety-related disorders generally fall into one of three categories:

• TCAs, SSRIs, and SNRIs, which help increase the amount of serotonin in the brain. Patients diagnosed with anxiety and depression often have lower levels of serotonin than those without a formal diagnosis⁶.
• Benzodiazepines, which help slow down the central nervous system and relieve stress.
• Beta-blockers, which reduce the effects of epinephrine and norepinephrine, stress hormones often linked to anxiety.

Many drugs in these categories are metabolized by CYP enzymes. This group includes SSRIs and SNRIs like citalopram (Celexa), escitalopram (Lexapro), fluoxetine (Prozac), fluvoxamine (Luvox), and duloxetine (Cymbalta). CYPs also metabolize benzodiazepines like diazepam (Valium) and beta-blockers like propranolol (Inderal).

When a clinician receives a patient’s pharmacogenetic test results, they review the report thoroughly with patients to provide education about medications that are therapeutic and eliminate those that may be detrimental based on genetic variations. The clinician can then use these results to create a proper treatment plan that is now unique to the patient.

For example, a person might have a genetic variation that can metabolize citalopram, a popular SSRI, very quickly upon ingestion. Knowing this, a provider might realize that the standard dosage of citalopram for anxiety treatment would be less effective. As a result, they might increase the dosage or prescribe a different drug in its place known to metabolize normally based on a patient’s PGx results.

On the contrary, some people have a genetic variation that causes the drug fluvoxamine, another SSRI, to be metabolized very slowly upon ingestion. As a result, the drug may remain in the body longer, making side effects more pronounced. Knowing this, a provider might decrease the dosage to prevent any negative side effects or switch to another medication that is metabolized at a normal rate based on a patient’s PGx results.

Why It Matters

According to the National Alliance on Mental Illness, it may take several weeks or up to a few months before a psychiatric medication begins to work effectively⁷. Often, patients with anxiety cycle through several different medication trials or dosages with minimal or no relief of anxiety symptoms.

Without the proper medication, days and weeks can add up, leading to an extended period of needless suffering before formulating an effective individualized treatment plan.

With pharmacogenetic testing, clinicians can provide quicker and improved psychiatric care by reducing the process of trial and error. PGx tests can help providers rule out various medications that would either not work or be minimally effective. This narrows the window of drugs to prescribe and makes the process of finding a drug that works much more straightforward. Moreover, tests could also give doctors guidance on dosage, which helps reduce adverse drug reactions.

By shortening the trial window and decreasing the chance of experiencing side effects, pharmacogenetic testing can help many people on their journey to manage anxiety with the appropriate medication(s).

Obtaining A Genetic Test

Those seeking to take a pharmacogenetic test can talk to their doctor about options or consult one of the many pharmacogenetic testing services to get a test on their own. Some companies, such as Genomind and Genesight, conduct standard genetic testing with no add-ons. Other services, such as Prairie Health, provide testing as part of an ongoing mental health care plan. Depending on the provider, a person can expect to pay for a pharmacogenetic test with insurance, out-of-pocket, or as part of a broader package.

Who Can Prescribe?

There are several ways to be prescribed with anxiety medication. Sometimes, a primary care physician (your regular doctor) will prescribe psychiatric medication to their patients. However, they might also refer patients to a psychiatrist or psychologist.

Psychiatrists are medical doctors that have undergone specialized training and are especially equipped to treat mental health disorders. If they are licensed, psychiatrists can prescribe medication in every US state.

Psychologists, on the other hand, are not medical doctors. Instead, they have a PhD or a doctoral degree in psychology (PsyD)⁸. Though both PhDs and PsyDs have studied psychology extensively, the course of study for PsyDs is more concerned with application in patient care, while PhDs are often trained to research or teach. Clinical psychologists are often PsyDs, though some may have PhDs.

Because psychologists are not medical doctors, there are more restrictions on what they can do. Most states do not allow psychologists to prescribe medication. The states that do (Louisiana, New Mexico, Illinois, Iowa, and Idaho) require psychologists to undergo extra training before they can begin prescribing⁹. There may also be restrictions depending on what psychologists are allowed to prescribe.

Also, able to prescribe medication are psychiatric mental health nurse practitioners (PMHNPs). PMHNPs are registered nurses who have undergone extra training in mental health care to be able to diagnose, treat, and prescribe medication to those with mental health disorders¹⁰. Restrictions on PMHNPs vary by state. In some places, they can work alone. In others, they must work under the supervision of a doctor.

Those seeking anxiety medication have different options for obtaining a prescription, and the best option for anyone depends on what they personally want out of their mental health care.

Working with Your Provider

One way to make sure that you get the most out of your anxiety treatment plan is to establish a good relationship with the provider managing your mental health care. Don’t be afraid to speak up if you’re struggling with medication side effects or need clarification regarding psychiatric diagnosis or other therapeutic interventions. After appointments, check in with yourself and ask whether you feel understood and supported regarding your mental health.  If yes, then you’re on the right track to improving your mental health.

Conclusion

Anxiety disorders can have a tremendous impact on daily functioning and affect the quality of life of those who struggle with it. Having an appropriate, individualized medication regimen can significantly help those struggling with anxiety. Because of pharmacogenetic testing, formulating an effective treatment plan is no longer an impossible task.

Pharmacogenetic testing can eliminate some of the guesswork and frustration of medication management for people who live with anxiety. As the field of pharmacogenetics advances, the way that clinicians treat and medicate patients with anxiety and other psychiatric disorders will continue to improve, evolve, and ultimately enhance a patient’s quality of life.