Imagine your brain as a vibrant city. Billions of houses—the nerve cells—stand close together. Between them lie tiny alleys, the synapses. This is where messages are handed over to keep the city moving: mood, drive, sleep, appetite, and concentration.

The mail carriers of this city are called messenger substances. When a cell wants to "communicate something," it sends messenger substances into the alley. On the other side, receiving stations are waiting. If enough messenger substances dock, the signal is passed on. Afterwards, the messenger substance is reabsorbed or broken down. This keeps the city in balance.

During prolonged stress, illness, or exhaustion, this balance gets disrupted: some alleys are overcrowded, others are almost empty, and the streetlights seem dimmed. That is exactly what depression feels like—heavier, slower, more colorless.

The good news: with treatment and small steps in daily life, the city can find its balance again: pathways are repaired, traffic lights are synchronized anew, and messages arrive once more.

The messenger substances in the brain play a key role in deciding how awake, calm, focused, or motivated we feel. The following overview shows what individual messenger substances stand for in daily life, what can happen during an imbalance—and what helps to counter it.

Depression, however, does not arise solely from messenger substances in the brain. Usually, several areas fall out of sync at once: how we think and handle stress, which habits shape our day, which experiences have shaped us—and how the messenger substances and networks in the brain react to them. This sounds complex, but it can be easily structured. Professionals summarize this in the bio-psycho-social model: three perspectives that together form a complete picture. The special thing about it: help can start at all three points—step by step, tailored to you and your daily life.

• Biology: Your genes, messenger substances, brain networks, as well as inflammatory and hormonal systems jointly influence how susceptible you are to depression. They decide how strongly symptoms manifest. These biological factors determine how your brain evaluates stress, processes signals, and stabilizes your mood.
• Psychology: Your thought patterns, coping styles, self-image, and learned experiences shape how you categorize situations and handle stress.
• Social factors: Burdening situations in the family, loneliness, or financial worries can create additional stress as framework conditions, making daily life harder. Consequently, withdrawal, lack of drive, and dejection reinforce each other.

Treatment for depression is tailored to how you are doing and what suits you. Generally, your doctor will discuss all options with you together:

• Psychotherapy: Cognitive behavioral therapy (CBT), interpersonal therapy, or mindfulness-based practices help to change thought patterns, build up activities, and strengthen relationships. Through this, many of those affected find energy and joy again.
• Antidepressants: Depending on the severity and duration of the depression, as well as the willingness of the patient, these support signal transmission in the brain. Their effect develops over weeks. Close medical supervision and patience are important.
• Self-coaching in daily life: You support yourself with regular exercise, good sleep hygiene, plenty of daylight, and regular social contact. These measures do not replace therapy, but they act like a booster for any treatment.

Remember the vibrant city that fell out of sync: some alleys crowded, others empty, the lighting dimmed. Antidepressants help to bring order back to the city—quietly, step by step.

• More time for the mail: Frequently prescribed medications ensure that the letters (messenger substances) remain in the alley longer. This way, more messages reliably reach their destination.
• Fine-tuning the reception: The "doorbells" of the houses (receptors) slowly adjust to become more sensitive. That is why those affected often do not feel the full effect until after 1 to 3 weeks—the city needs time to synchronize its traffic lights anew.
• Paving new pathways: When small things start to succeed again—a short walk, a phone call, a completed task—the streets learn to handle the good traffic. Wobbly paths turn into solid roads, and the mood stabilizes.

In short: antidepressants bring calm, order, and light back to the city—and together with therapy and everyday steps, the city permanently finds its rhythm again.

deprexis is an approved Digital Health Application (DiGA) available on prescription. It offers easy-to-understand information, exercises, and support for daily life. Studies show positive effects when used as a complement to treatment. A digital health application does not replace in-person therapy, but it can motivate, provide knowledge, and bridge waiting times.