Compare conditions

Put any two — or three — conditions side by side, adult or pediatric, to spot the look-alike differences fast, row by row.

Depression

—

In one line

·Depression is a medical condition in which the brain's mood and motivation systems stop working properly, causing persistent sadness, loss of interest, and changes in sleep, appetite, energy, and thinking that last at least two weeks.

—

Normal physiology

·The brain uses chemical messengers called neurotransmitters, especially serotonin, norepinephrine, and dopamine, to control mood, motivation, sleep, appetite, energy, and thinking. These chemicals travel between nerve cells, called neurons, in specific brain regions like the prefrontal cortex (the front of the brain that plans and regulates feelings), the limbic system (the emotion center deep inside), and the hypothalamus (the body's control tower for sleep and hunger). When this system is balanced, you feel okay, bounce back from stress, enjoy activities, sleep well, eat normally, and think clearly.

—

What goes wrong

·In depression, the brain does not make enough serotonin, norepinephrine, and dopamine, or it reabsorbs them too quickly, or the receptors do not respond well, so the mood, motivation, sleep, appetite, and thinking circuits do not get the signals they need. This can be triggered by genes you inherit — family history of depression increases risk — or ongoing stress, which raises cortisol (the body's main stress hormone) that damages neurons and lowers neurotransmitter production. Trauma, medical illness like thyroid disease or stroke or chronic pain, some medicines like steroids or beta-blockers, or substance use can also set it off. The break often starts in the limbic system (the emotion center) and spreads to the prefrontal cortex (the thinking center), disrupting both emotion and thinking.

—

Hallmark signs

·Feeling sad, empty, or hopeless most of the day, nearly every day
·Loss of interest or pleasure in activities you used to enjoy
·Trouble sleeping (sleeping too much or too little)
·Feeling tired or having very low energy almost every day
·Changes in appetite or weight (eating much more or much less than usual)
·Trouble concentrating, remembering things, or making decisions
·Feeling worthless or excessively guilty about things
·Moving or speaking more slowly than usual, or being restless and unable to sit still

—

Red flags · escalate now

·Thoughts of suicide, a plan to hurt yourself, or telling others you want to die
·Hearing voices or seeing things that are not there (psychotic depression)
·Complete inability to care for yourself — not eating, not getting out of bed, not speaking
·Rapid weight loss or severe malnutrition from not eating
·New confusion, severe memory loss, or fast worsening of thinking (may signal severe depression or another medical cause)

—

Workup

·PHQ-9 (Patient Health Questionnaire-9)
·TSH (thyroid-stimulating hormone)
·Complete blood count (CBC)
·Comprehensive metabolic panel (CMP)
·Vitamin B12 and folate levels
·Urine drug screen
·24-hour urinary free cortisol or late-night salivary cortisol (if Cushing syndrome is suspected based on physical exam findings like central weight gain, purple stretch marks, easy bruising)
·HIV antibody test (in appropriate clinical context)

—

Treatment

·Safety assessment and suicide risk plan
·Selective serotonin reuptake inhibitor (SSRI, like sertraline, escitalopram, or fluoxetine) or serotonin-norepinephrine reuptake inhibitor (SNRI, like venlafaxine or duloxetine)
·Cognitive behavioral therapy (CBT) or interpersonal psychotherapy (IPT)
·Fix sleep schedule (same bedtime and wake time every day, even on weekends) and add regular aerobic exercise (30 minutes, 5 days a week)
·Stop all drug and alcohol use
·Add bupropion, mirtazapine, or switch to a different antidepressant (if first SSRI or SNRI fails after 6 to 8 weeks at full dose)
·Add aripiprazole or quetiapine (atypical antipsychotics), lithium, esketamine nasal spray, or electroconvulsive therapy (ECT) for treatment-resistant depression (failed 2 or more antidepressants)

—

NCLEX trap

·Depression is not one symptom — it is a cluster. Always screen using PHQ-9 (a nine-question tool that measures how deep the depression is). Always ask about suicide directly. Sadness is what you see on the outside; the real break is in brain chemicals — serotonin (the messenger that steadies mood and sleep), norepinephrine (the messenger that controls energy and focus), and dopamine (the messenger that drives pleasure and reward) — all running too low.
·When depression is severe and suicide risk is high: make the patient safe first. Build a written safety plan (who to call, how to cope, what warning signs look like), remove access to lethal means like guns or pills, consider hospital admission if risk is right now. Then start medicine and therapy. The first few weeks of SSRI treatment can actually increase suicide risk in people under 25 — the medicine gives energy back before it lifts mood, so the person suddenly has the fuel to act on dark thoughts. Watch closely during this window.
·Body pain in depression is often a somatic symptom caused by the mood disorder itself, not a broken organ. The same brain chemical imbalance that causes sadness also changes how the brain reads pain signals — the anterior cingulate cortex (the brain's alarm center for distress) and the insula (the part that maps body sensations) overfire and make normal body signals feel like pain. Treat the depression first. If the pain came from depression, it will fade as mood improves.
·Depression is a real break in brain chemistry — low serotonin, norepinephrine, and dopamine — not a choice or a character flaw. The limbic system (the brain's emotion center, including the amygdala and hippocampus) and the nucleus accumbens (the brain's reward center) are not working right. The prefrontal cortex (the front part of the brain that controls planning and brakes negative thinking) loses control over the emotional centers. This is biology, like diabetes or high blood pressure. Medicine and therapy fix the broken chemistry and thought patterns.
·After you start an SSRI: see the patient in 1–2 weeks to check for side effects (nausea, jitteriness, sexual problems) and early suicide risk. Wait 4–6 weeks to see if mood improves. If not working by 6–8 weeks, increase dose, switch to a different SSRI, or add a second medicine (like bupropion or mirtazapine). Depression needs close follow-up, not abandonment. Roughly 30% of people do not respond to the first SSRI — you have to keep adjusting until you find what works.

—

Install Maldek by Hill as an app — studies work even offline