Genetic Testing for Psychiatric Medications 2025

Explaining Genetic Testing for Psychiatric Medications

Known as pharmacogenetic, pharmacogenomic, or PGx testing, genetic testing for psychiatric medications is readily available for both doctors and patients. At AttoDiagnostics, we primarily serve the doctor, whether they’re in the NHS or private practice. In 2025, most PGx testing is conducted in a private practice setting and in the NHS through the Genomic Laboratory Hubs.

However, if a patient was transitioning from the NHS to private, they might do their own genetic test to guide the private doctor about their response and possible side effects to medications. It’s important to note that in the UK, the patient does not self-prescribe. The doctor always owns the prescribing relationship.

What Psychiatric Conditions are Typically Covered by Genetic Testing?

At AttoDiagnostics, our pharmacogenomics test covers over 20 conditions and 115 verified or key medications which are actionable through PGx testing. Within the psychiatric space, depression, anxiety, bipolar disorder, schizophrenia, and ADHD are the main conditions we focus on. Head here to explore PGx testing for mental health conditions.

The benefits of PGx affect directly not only the patients, in terms faster and better treatment outcomes, but also the UK as a whole: Using DNA-driven prescriptions could prevent 15% of hospital admissions, saving the NHS over £530 million yearly through ADR-related admissions.

Finding the Right Depression Medication for Your Patient

Genetic Testing for SSRIs

If your patient is searching, “how to know which SSRI is right for you?” or if they are considering citalopram or sertraline, a genetic test is a good start. These SSRIs are metabolised through two different pathways. As this blogger describes, sertraline is recommended for them, whereas citalopram is not. This is because citalopram is primarily processed through the CYP2C19 gene, while sertraline is metabolised via CYP2C19 and CYP2D6 genes.

If a patient is a rapid metaboliser of citalopram (as the blogger is), their body may clear the drug too quickly, preventing it from reaching sustained therapeutic levels. In contrast, sertraline may be a more effective option for them.

Genetic Testing for Tricyclic Antidepressants (TCAs)

For patients who require tricyclic antidepressants (TCAs) such as amitriptyline, nortriptyline, or imipramine, pharmacogenomic insights are also valuable. Similar to citalopram and sertraline, TCAs are metabolised primarily through CYP2D6 and CYP2C19 gene, meaning genetic variations in these genes can significantly impact drug levels and side effect profiles.

Finding the Right Anxiety Medication for Your Patient

Anxiety disorders are commonly treated with SSRIs, similar to depression, but benzodiazepines (such as diazepam, lorazepam, and alprazolam) are also frequently prescribed for short-term relief of acute symptoms. Genetic variations in metabolism can influence both the effectiveness and safety of these medications.

Benzodiazepines: Genetic Considerations

Unlike SSRIs, benzodiazepines work by enhancing GABA activity in the brain, producing sedative and anxiolytic effects. Many benzodiazepines, including diazepam, are metabolised primarily through CYP2C19 and CYP3A4, meaning genetic variations can lead to unexpected drug accumulation or rapid clearance.

For example, CYP2C19 poor metabolisers may experience stronger and prolonged sedative effects from diazepam due to slower clearance.

Finding the Right Bipolar Disorder Treatment for Your Patient

Aripiprazole, quetiapine, and olanzapine are all covered in the AttoDiagnostics report. These drugs are used in bipolar disorder to stabilise mood and treat acute mania. They are primarily metabolised via CYP2D6 and CYP3A4, meaning genetic variations can affect their plasma concentrations and side effect profiles.

• CYP2D6 poor metabolisers may experience higher drug levels, leading to an increased risk of sedation, weight gain, and metabolic side effects with medications like quetiapine and olanzapine.

• Ultra-rapid metabolisers of CYP2D6 may clear drugs like aripiprazole or risperidone too quickly, potentially reducing their effectiveness.

Understanding Drug-Drug Interactions for Those With Bipolar Disorder

Patients with bipolar disorder are often prescribed multiple medications, which can lead to drug-drug interactions (DDIs) if they share the same metabolic pathways.

For example, carbamazepine (a mood stabiliser) is a strong inducer of CYP3A4, meaning it can significantly reduce the effectiveness of quetiapine (an antipsychotic) by increasing its breakdown. As a result, a patient who requires both medications may need a higher dose of quetiapine to maintain therapeutic levels. Conversely, if a patient is prescribed fluoxetine (an SSRI) alongside aripiprazole, fluoxetine’s CYP2D6 inhibition can lead to elevated aripiprazole levels, increasing the risk of side effects like drowsiness and movement disorders (EPS). 

Even dietary factors can play a role in drug metabolism. Quetiapine and some benzodiazepines (such as diazepam) rely on CYP3A4, which can be inhibited by grapefruit juice, leading to unexpectedly high drug concentrations in the bloodstream. This can result in increased sedation and dizziness, particularly in patients already on multiple central nervous system depressants.

PGx testing helps doctors anticipate these interactions and potential serious adverse drug reactions, which ensures medications are adjusted to maintain effectiveness without causing excessive sedation, toxicity, or withdrawal effects.

Genetic Testing for Schizophrenia

Schizophrenia treatment typically involves antipsychotic medications, which vary in their effectiveness and side effect profiles based on a patient’s genetic makeup. Since most antipsychotics are metabolised by a gene which encodes a cytochrome P450 enzyme, pharmacogenomic testing can help predict how a patient will respond, minimising the risk of ineffective treatment, excessive side effects, or adverse drug reactions.

Clozapine (Clozaril): A Special Case

Clozapine is a drug that receives a lot of attention in PGx circles, due to the risk of agranulocytosis (a severe drop in white blood cells). PGx testing can help predict metabolism speed, ensuring appropriate dosing while minimising the risk of toxicity.

Looking outside of Clozapine, genetic testing for Risperidone (Risperdal) and Aripiprazole (Abilify) is effective as these drugs are metabolised by CYP2D6.

• If your patient is a poor metaboliser, the drugs build up over time and lead to increased drowsiness, weight gain, and movement disorders (EPS).

• For rapid metabolisers, the drug may clear too quickly, making it less effective at controlling symptoms.
  
  

Genetic Testing for People with ADHD

Many patients might ask, “Is ADHD genetic?” or “Is ADHD hereditary?” To which, the answer is “Yes, there are strong genetic components to ADHD” which means that a patient may well inherit it from their parents. And as you might expect, there is a strong genetic component to the efficacy of the medication as well. 

Broadly, ADHD treatments fall into two main categories: stimulants and non-stimulants.

• Stimulants include methylphenidate (Ritalin, Concerta) and amphetamine-based medications (Adderall, Vyvanse/Lisdexamfetamine), which increase dopamine and norepinephrine activity to improve focus and impulse control.

• Non-stimulants include atomoxetine (Strattera), guanfacine (Intuniv), and clonidine (Kapvay), which work through different neurotransmitter systems and may be used when stimulants are ineffective or cause side effects.

Even within the same category, not all drugs are metabolised in the same way, as you can see in the following case study.

Case Study: Personalising ADHD Medication with PGx Testing

A patient diagnosed with adult ADHD was initially prescribed methylphenidate, however, they experienced nausea and persistent dry mouth, which made adherence difficult.

A PGx test revealed:

• ADRA2A genetic variation or C/C genotype, which is linked to a poorer response to methylphenidate or associated with reduced efficacy of methylphenidate.

Based on these results, the doctor switched the patient to lisdexamfetamine (Vyvanse), an amphetamine-based stimulant, which provided better symptom control with fewer side effects. This case highlights how PGx testing can guide medication selection, ensuring a more effective and tolerable treatment plan.

How PGx Testing Helps in ADHD Treatment

• Methylphenidate (Ritalin, Concerta) is primarily metabolised by CES1A1, meaning genetic variants in this enzyme can influence its effectiveness and side effects.

• Amphetamines (Adderall, Vyvanse/Lisdexamfetamine) rely on CYP2D6, so poor metabolisers may experience stronger stimulant effects, while ultra-rapid metabolisers may clear the drug too quickly.

• Atomoxetine (Strattera) is heavily influenced by CYP2D6; poor metabolisers may experience stronger effects and side effects, while ultra-rapid metabolisers may find the drug ineffective.
  
  

DNA Testing for Psychiatric Medications UK

If you’re a doctor considering personalised prescribing, precision prescribing, or genetic testing for psychiatric medications UK, you can book a pharmacogenomics demo with our team or check our training webinar dates for information.

If you are a patient and would like to take a PGx test and approach your doctor, head over to AttoPGx, where you can shop our range of genetic tests for psychiatric medications.

Request a PGx Demo