How Effective are Antidepressants?

Table of Content

• How do antidepressants work?

• Different Types of Antidepressants

• Effectiveness of Antidepressants

• Duration and Doses of Antidepressants

• Side effects of Antidepressants

• Take-Home Points

• FAQ on How Effective are Antidepressants?

Introduction

Antidepressants are a class of medication that helps treat various mental health conditions and sometimes chronic pain. Depression is a common mental illness. The WHO reports show that about 280 million people have depression. Depression can cause the affected person to suffer considerably, function poorly, and even could lead to suicide. Depression affects the brain, so drugs that work on the brain may prove helpful. Antidepressants are known to lessen the symptoms of depression, but there are many other options too.

The effectiveness of antidepressants in relieving symptoms of depression varies. They are probably not helpful in mild cases of depression but are effective in moderate, severe, and chronic depression. Though antidepressants focus on making the person emotionally stable and helping them follow an everyday life, they have many side effects too. 

How do Antidepressants work?

The exact way how antidepressants work is unknown. However, experts think that antidepressants cause an increase in the levels of brain chemicals known as neurotransmitters. Emotion and mood have a link with neurotransmitters like noradrenaline and serotonin. Moreover, neurotransmitters can affect nerve pain signals, which may describe why some antidepressants can help reduce long-term pain.

Antidepressants are often used along with therapy to treat more severe depression and other mental health conditions, as they may not always address the cause.

Different Types of Antidepressants

The different types of antidepressants include:

1. Selective serotonin reuptake inhibitors (SSRIs)

They are the most commonly prescribed antidepressant. They have fewer side effects when compared to other antidepressants.

Fluoxetine is likely the best-known SSRI. Other SSRIs includesertraline, paroxetine, escitalopram, andcitalopram.

2. Serotonin-noradrenaline reuptake inhibitors (SNRIs)

SNRIs are similar to SSRIs. The commonly used SNRIs include duloxetine and venlafaxine.

3. Noradrenaline and specific serotonergic antidepressants (NASSAs)

NASSAs can be effective in some people who can not take SSRIs. Moreover, the side effects of NASSAs and SSRIs are similar. The commonly prescribed NASSA is Mirtazapine. Other NASSAs include Aptazapine, Esmirtazapine, and Mianserin. 

4. Serotonin antagonists and reuptake inhibitors (SARIs)

SARIs are not the first choice of antidepressants, but they are often given to patients when other antidepressants have caused side effects or have not worked.

The main SARI prescribed is trazodone.

5. Tricyclic antidepressants (TCAs)

TCAs are first-generation antidepressants. SNRIs and SSRIs are second-generation antidepressants. These days they are no longer recommended as they can be more dangerous in an overdose and cause more undesirable side effects than SNRIs and SSRIs.

TCAs include nortriptyline, dosulepin, clomipramine, imipramine, lofepramine, and amitriptyline. Amitriptyline can be used in patients to treat chronic nerve pain.

6. Monoamine oxidase inhibitors (MAOIs)

These days MAOIs are no longer recommended as they can cause potentially severe side effects.

MAOIs include phenelzine, tranylcypromine, and isocarboxazid.

Effectiveness of Antidepressants

The effectiveness of antidepressants in relieving symptoms of depression varies. They are helpful in moderate, severe, and chronic depression but are not so effective in mild cases of depression. Multiple studies have been conducted over the years to find the effectiveness of antidepressants.

• A data analysis conducted in 2020 looked at previously published data on the efficacy of antidepressants. The study checked whether previous studies underestimated the efficacy of antidepressants due to the use of HDRS or the Hamilton Depression Rating Scale. Researchers used another alternative measurement, MADRS or the Montgomery-Asberg Depression Rating Scale (the gold standard clinician rating scale).

The researchers found that the earlier studies did not underestimate effectiveness but hypothesized that antidepressants might not work well for the average person.

• A systematic review and single-group meta-analysis were conducted in 2020 on the effectiveness of antidepressants in older adults with major depressive disorder. The researchers checked multiple databases for RCT (randomized controlled trials) on antidepressants in older adults with major depressive disorder. 50% improvement on rating scales was the defined response.

Researchers collected response rates from studies and imputed the missing responses with a validated method. The analysis looked at 44 studies conducted on 6,373 participants and concluded that based on the HDRS, about 50.7 percent of participants achieved at least a 50 percent reduction in depression.

• Another meta-review in 2020 based on 34 random controlled trials involving the efficacy of 14 antidepressants prescribed for major depressive disorder in adolescents and children found that only fluoxetine worked better than the placebo. 

• The researchers studied the efficacy of antidepressants in patients to prevent relapse. They found that taking antidepressants like TCAs, SNRIs, or SSRIs can reduce the risk of relapses but can not completely prevent them.

The clinical study randomized 200 participants into two groups. The first group did not take antidepressants, while the second took antidepressants. The results were as follows:

• About 50 out of 100 people who did not take the antidepressants had a relapse within 1-2 years.

• About 23 out of 100 people who took the antidepressant had a relapse within 1-2 years.

The study showed that taking an antidepressant for an extended period successfully prevented a relapse in an average of 27 out of 100 people.

Duration and Doses of Antidepressants

Antidepressants are available in tablet form and started with the lowest possible dose necessary to improve the symptoms. Depending on the severity of the depression and the type of antidepressant prescribed, one may have to take 1-3 tablets a day.

To feel the benefit of antidepressants, the patient must take them for 1 to 2 weeks without missing a dose. It's necessary to continue taking them even if one gets mild side effects initially, as these effects usually wear off quickly. Missing a dose could make the treatment less effective, but it is necessary not to take more than the prescribed dose. However, if no benefits are felt even after taking it for more than four weeks, change the dosage or use a different medicine after discussing it with the mental health specialist or physician. 

Sudden stopping of antidepressants can cause withdrawal symptoms like dizziness, anxiety, stomach upsets, flu-like symptoms, etc.

Side effects of Antidepressants

Different antidepressants have different side effects. The common side effects are mild and improve within days or weeks of treatment as the body gets used to the medication.

The side effects of SSRIs and SNRIs include the following

• anxiety

• stomach aches

• Feeling sick

• Constipation or diarrhea

• loss of appetite

• insomnia

• dizziness

• headaches

• erectile dysfunction

• loss of libido

Common side effects of TCAs can include the following

• blurred vision

• Xerostomia or dry mouth

• drowsiness

• dizziness

• constipation

• difficulty in passing urine

• weight gain

• Night sweating

• heart rhythm problems - palpations, arrhythmia, and tachycardia

Potential health risks

• SNRI or SSRI combined with another medicine that increases serotonin leads to high serotonin levels in the brain, which causes serotonin syndrome. Severe symptoms of serotonin syndrome are arrhythmia, fits, and unconsciousness. 

• Patients who use SSRIs and TCAs for more prolonged periods are at a higher risk of developing type 2 diabetes.

• Old patients who take SSRIs may experience a severe drop in sodium levels, known as hyponatremia. Hyponatremia could result in a fluid build-up inside the body's cells, which can be dangerous. The most severe cases of hyponatremia can cause the patient to enter a coma or even stop breathing.

• Some patients, especially young adults, experience the desire to self-harm when they first take the antidepressants. 

Take-Home Points

• Antidepressants are a class of medication that helps treat various mental health conditions and sometimes chronic pain. Antidepressants are known to lessen the symptoms of depression, but their effectiveness varies from case to case. They are effective in moderate, severe, and chronic depression but are not so helpful in mild cases of depression.

• There are different types of antidepressants which include SSRIs (Selective serotonin reuptake inhibitors), SNRIs (Serotonin-noradrenaline reuptake inhibitors), NASSAs (Noradrenaline and specific serotonergic antidepressants), and TCAs (Tricyclic antidepressants).

• Various data and studies show that antidepressants are effective in treating and preventing relapse of depression in some people though they cause some side effects. Depending on the severity of the depression and the type of antidepressant prescribed, one may have to take 1-3 tablets a day. To feel the benefit of antidepressants, the patient must take them for 1 to 2 weeks without missing a dose.

References

• Depression: How effective are antidepressants?

• Antidepressants

• Overview - Antidepressants

• Side effects - Antidepressants

• Efficacy of new-generation antidepressants

• Response to antidepressants

• Antidepressants in Children and Adolescents