May 3, 2021
Mental illness affects 51.5 million American adults, according to the 2019 National Survey on Drug Use and Health.¹ That’s more than chronic kidney disease (37 million), diabetes (34.2 million), or heart disease (30.3 million). Among those 51.5 million people are 13.1 million people who have serious mental illness, which is defined as a disorder that impedes life activities, such as sleeping, working, or caring for yourself.
Although mental illness is common, its symptoms and their severity vary greatly among individual patients. The International Statistical Classification of Diseases (ICD) describes 300 different mental and behavioral disorders. Additional complicating factors make the diagnosis and treatment of mental illness difficult:²
Clearly, mental illness requires a personalized treatment approach.
In most cases in the United States, mental illness treatment involves one or more medications, often in combination with talk therapy. The 2019 National Health Interview Survey, conducted by the National Center for Health Statistics, found that 15.8% of American adults had taken prescription medication for their mental health in the past 12 months.³ But finding the right combination of medications to reduce a patient’s symptoms with minimal side effects often involves some trial and error.
Precision prescribing takes a patient’s unique combination of genes, environment, and lifestyle into account to make the prescribing process more efficient and effective. With this approach, prescribers and pharmacists work together to provide individualized medication plans. Research has identified several factors that are likely to affect how psychiatric medications will work in specific patients.
Pharmacogenetics studies variations in DNA and how these variations affect the way patients metabolize drugs. The way a patient metabolizes a drug affects medication dosage. Fast metabolizers may need higher doses to achieve the desired effect; slow metabolizers may need lower doses to avoid severe side effects. A pharmacogenetic test of a patient’s blood or saliva shows which genetic variations a patient has. This test only has to be done once, because the patient’s DNA will not change.
Because the liver is where drugs are metabolized, pharmacogenetic studies focus on genes that code liver enzymes. One of these genes, CYP2D6, helps break down 25% of the most prescribed medications.4 The medications listed in the following groups all include pharmacogenomic information related to this gene on their labels.
Table 1: Mental Health Medications with Pharmacogenomic Labeling for CYP2D6
|Drug Type||Drug Name||Disorder Treated|
|Selective serotonin reuptake inhibitors (SSRIs)||citalopram (Celexa)
|Serotonin norepinephrine reuptake inhibitors (SNRIs)||desvenlafaxine
Depression and Generalized Anxiety Disorder
|Serotonin modulators and stimulators (SMS)||nefazodone
|bupropion (Wellbutrin)||Depression and Seasonal Affective Disorder|
|Atypical antipsychotics||aripiprazole (Abilify) brexpiprazole (Rexulti) cariprazine
|Bipolar Disorder and Schizophrenia|
|amphetamine||Attention Deficit Hyperactivity Disorder|
In addition to CYP2D6, these genes are considered “clinically actionable”:5
Pharmacogenomics studies how gene function is affected by environment changes. Unlike the genes themselves, environmental factors that affect how the genes work can change. This is where a detailed patient history and complete list of the patient’s prescriptions and herbal supplements come in handy.
Consider just some of the environmental factors that affect the CYP1A2 gene that metabolizes tricyclic antidepressants and conventional antipsychotics:4
The likelihood of taking mental health prescriptions varies depending on sex, race/ethnicity, location, and age among U.S. adults, as does the prevalence of serious mental illness:1, 3
A patient’s age also affects the risk involved in taking psychiatric medications:
Providers and pharmacists need a way to bring all these factors together to help customize a mental health treatment plan for specific patients. PrecisionRx Advisor™ removes the barriers that stand in the way of precision prescribing. It is the only unified platform that combines patient-specific data from conventional medication therapy management and pharmacogenetic and clinical lab testing with integrated engagement and monitoring workflows to recommend informed improvements to the patient’s prescription plan and overall care. Click here to learn about hc1’s precision prescribing solutions.