Like other medical problems, psychological disorders may in some cases be treated biologically. Biomedical therapies are treatments designed to reduce psychological disorder by influencing the action of the central nervous system. These therapies primarily involve the use of medications but also include direct methods of brain intervention, including electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), and psychosurgery.

Drug Therapies

Psychologists understand that an appropriate balance of neurotransmitters in the brain is necessary for mental health. If there is a proper balance of chemicals, then the person’s mental health will be acceptable, but psychological disorder will result if there is a chemical imbalance. The most frequently used biological treatments provide the patient with medication that influences the production and reuptake of neurotransmitters in the central nervous system (CNS). The use of these drugs is rapidly increasing, and drug therapy is now the most common approach to treatment of most psychological disorders.

Unlike some medical therapies that can be targeted toward specific symptoms, current psychological drug therapies are not so specific; they don’t change particular behaviours or thought processes, and they don’t really solve psychological disorders. However, although they cannot “cure” disorders, drug therapies are nevertheless useful therapeutic approaches, particularly when combined with psychological therapy, in treating a variety of psychological disorders. The best drug combination for the individual patient is usually found through trial and error (Biedermann & Fleischhacker, 2009).

The major classes and brand names of drugs used to treat psychological disorders are shown in Table PY.2.

Antipsychotic Medications

Until the middle of the 20th century, schizophrenia was inevitably accompanied by the presence of positive symptoms, including bizarre, disruptive, and potentially dangerous behaviour. As a result, schizophrenics were locked in asylums to protect them from themselves and to protect society from them. In the 1950s, a drug called chlorpromazine (Thorazine) was discovered that could reduce many of the positive symptoms of schizophrenia. Chlorpromazine was the first of many antipsychotic drugs.

Antipsychotic drugs (neuroleptics) are drugs that treat the symptoms of schizophrenia and related psychotic disorders. Today there are many antipsychotics, including Thorazine, Haldol, Clozaril, Risperdal, and Zyprexa. Some of these drugs treat the positive symptoms of schizophrenia, and some treat the positive, negative, and cognitive symptoms.

The discovery of chlorpromazine and its use in clinics has been described as the single greatest advance in psychiatric care, because it has dramatically improved the prognosis of patients in psychiatric hospitals worldwide. Using antipsychotic medications has allowed hundreds of thousands of people to move out of asylums into individual households or community mental health centres, and in many cases to live near-normal lives.

Antipsychotics reduce the positive symptoms of schizophrenia by reducing the transmission of dopamine at the synapses in the limbic system, and they improve negative symptoms by influencing levels of serotonin (Marangell, Silver, Goff, & Yudofsky, 2003). Despite their effectiveness, antipsychotics have some negative side effects, including restlessness, muscle spasms, dizziness, and blurred vision. In addition, their long-term use can cause permanent neurological damage, a condition called tardive dyskinesia that causes uncontrollable muscle movements, usually in the mouth area (National Institute of Mental Health, 2008). Newer antipsychotics treat more symptoms with fewer side effects than older medications do (Casey, 1996).

Antidepressant Medications

Antidepressant medications are designed to improve mood and are predominantly used in treating depression. They are also effective in managing anxiety disorders, phobias, and obsessive-compulsive disorders. These drugs typically modify the production and uptake of neurotransmitters like serotonin, norepinephrine, and dopamine, crucial for regulating emotion. While the detailed mechanisms are not fully understood, it is recognised that enhancing neurotransmitter levels in the central nervous system can significantly reduce symptoms of depression (Cipriani et al., 2018).

Historically, depression treatment included tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs), which increase neurotransmitter availability but are associated with severe side effects, including cardiovascular risks and dietary restrictions due to potential severe interactions with certain foods.

Today, selective serotonin reuptake inhibitors (SSRIs) such as Prozac, Zoloft, and Celexa are the most commonly prescribed antidepressants. These drugs predominantly block the reuptake of serotonin, increasing its concentration in the central nervous system. SSRIs are preferred due to their relatively safe profile and fewer side effects compared to TCAs and MAOIs. However, they also can have significant side effects; patients may experience issues such as gastrointestinal disturbances, sexual dysfunction, and emotional blunting (Hieronymus et al., 2016).

Concerns about SSRIs potentially increasing the risk of suicidal thoughts among teens and young adults continue to be debated, with newer studies urging caution and a balanced approach to prescribing these medications in vulnerable populations (Cipriani et al., 2018). The onset of antidepressant effects can be slow, often requiring several weeks to months to be effective, necessitating tailored treatment plans for individual patients. This slow ramping up to full dose can leave patients under-medicated and suffering with their symptoms for weeks.

Serotonin-norepinephrine reuptake inhibitors (SNRIs) like Effexor and Cymbalta, and norepinephrine reuptake inhibitors (NRIs) such as Wellbutrin, are also popular. SNRIs are known to enhance both serotonin and norepinephrine levels, improving mood and energy, while NRIs primarily increase norepinephrine, helpful in treating depression and aiding smoking cessation. These classes of antidepressants also have side effects and may cause nausea, dizziness, and insomnia (Fornaro et al., 2019).

Recent research has also explored the therapeutic potentials of psychedelics such as psilocybin, LSD, DMT, and Ayahuasca for treating various psychiatric disorders including depression, PTSD and anxiety. These substances interact with serotonin receptors in the brain and have shown promise in altering perception, mood, and cognitive processes, although they can also induce significant sensory and psychological alterations (Carhart-Harris et al., 2017).

Using Stimulants to Treat ADHD

Attention-deficit/hyperactivity disorder (ADHD) is frequently treated with biomedical therapy, usually along with cognitive behavioural therapy (CBT). The most commonly prescribed drugs for ADHD are psychostimulants, including Ritalin, Adderall, and Dexedrine. Short-acting forms of the drugs are taken as pills and last between 4 and 12 hours, but some of the drugs are also available in long-acting forms (skin patches) that can be worn on the hip and last up to 12 hours. The patch is placed on the child early in the morning and worn all day.

Stimulants improve the major symptoms of ADHD, including inattention, impulsivity and hyperactivity, often dramatically, in about 75% of the children who take them (Greenhill, Halperin, & Abikof, 1999). But the effects of the drugs wear off quickly. Additionally, the best drug and best dosage vary from child to child, so it may take some time to find the correct combination.

It may seem surprising to you that a disorder that involves hyperactivity is treated with a psychostimulant, a drug that normally increases activity. The answer lies in the dosage. When large doses of stimulants are taken, they increase activity, but in smaller doses the same stimulants improve attention and decrease motor activity (Zahn, Rapoport, & Thompson, 1980).

The most common side effects of psychostimulants in children include decreased appetite, weight loss, sleeping problems, and irritability as the effect of the medication tapers off. Stimulant medications may also be associated with a slightly reduced growth rate in children, although in most cases growth isn’t permanently affected (Spencer, Biederman, Harding, & O’Donnell, 1996).

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Mood Stabilisers: Lithium

Patients who are suffering from bipolar disorder are not helped by the SSRIs or other antidepressants because their disorder also involves the experience of overly positive moods. Treatment is more complicated for these patients, often involving a combination of antipsychotics and antidepressants along with mood stabilising medications (McElroy & Keck, 2000). The most well-known mood stabilser, lithium carbonate (or lithium), is used widely to treat mania associated with bipolar disorder. Available in Canada for more than 60 years, the medication is used to treat acute manic episodes and as a long-term therapy to reduce their frequency and severity. Anticonvulsant medications can also be used as mood stabilisers. Another drug, Depakote, has also proven very effective, and some bipolar patients may do better with it than with lithium (Kowatch et al., 2000).

People who take lithium must have regular blood tests to be sure that the levels of the drug are in the appropriate range. Potential negative side effects of lithium are loss of coordination, slurred speech, frequent urination, and excessive thirst. Though side effects often cause patients to stop taking their medication, it is important that treatment be continuous, rather than intermittent. Recently, Health Canada updated safety information and treatment recommendations for lithium after finding that taking lithium carries a risk of high blood calcium, or hypercalcemia, and is sometimes associated with a hormone disorder known as hyperparathyroidism (The Canadian Press, 2014). There is no cure for bipolar disorder, but drug therapy does help many people.

Anti-anxiety Medications

Antianxiety medications are drugs that help relieve fear or anxiety. They work by increasing the action of the neurotransmitter GABA. The increased level of GABA helps inhibit the action of the sympathetic division of the autonomic nervous system, creating a calming experience.

The most common class of antianxiety medications is the tranquilizers, known as benzodiazepines. These drugs, which are prescribed millions of times a year, include Ativan, Valium, and Xanax. The benzodiazepines act within a few minutes to treat mild anxiety disorders but also have major side effects. They are addictive, frequently leading to tolerance, and they can cause drowsiness, dizziness, and unpleasant withdrawal symptoms including relapses into increased anxiety (Otto et al., 1993). Furthermore, because the effects of the benzodiazepines are very similar to those of alcohol, they are very dangerous when combined with it.

Psychedelic-assisted therapy

Psychedelic-assisted therapy is emerging as a promising treatment option for various mental health disorders, notably treatment-resistant depression and PTSD. Conducted under stringent clinical supervision, this innovative therapeutic approach integrates the controlled use of psychedelic substances like psilocybin and MDMA into psychotherapy sessions, designed to facilitate profound psychological insights and emotional processing.

Recent research highlights the effectiveness of these therapies. Significant reductions in depression symptoms have been documented following psilocybin-assisted therapy, with sustained effects over time (Davis et al., 2020). Psilocybin activates serotonin receptors in the brain, which appears to “reset” neural circuits that contribute to depressive symptoms. Similarly, MDMA has shown promise in facilitating emotional breakthroughs in PTSD treatment by enhancing neurotransmitter activity — serotonin, norepinephrine, and dopamine — that elevates mood and diminishes the fear response, allowing patients to engage more effectively with therapeutic interventions (Mitchell et al., 2021).

The safety of psychedelic therapy is well-documented in clinical research, with a noted low abuse potential and absence of overdose fatalities (Johnson et al., 2017). Common side effects are generally transient and include nausea and headaches, manageable within a clinical setting. Strict adherence to therapeutic dosing and protocols reduces MDMA’s neurocognitive effects (Jerome et al., 2020).

Given the potent nature of psychedelic substances, regulatory guidelines are rigorous. Treatment is restricted to controlled environments with professional oversight to ensure patient safety and maximise therapeutic outcomes (Feduccia et al., 2018).

As research progresses and regulatory frameworks evolve, psychedelic-assisted therapy may offer a viable alternative to conventional treatments, particularly for patients who have not responded to traditional therapy modalities. This approach represents a significant paradigm shift in the treatment of mental health disorders, combining established psychotherapeutic techniques with the therapeutic potential of psychedelic substances.