What causes depression and how can I tell if I’m experiencing it?
Summary
Depression develops when inherited risk genes, brain-chemical imbalances, hormone shifts and repeated life stress interact. The result is low mood, loss of interest and body changes that persist for at least two weeks and cause clear difficulty at home, school or work. If you notice these symptoms or any thoughts of self-harm, seek help promptly—effective therapies range from lifestyle steps and talk therapy to medicines and digital tools like Eureka’s AI doctor.
What actually causes depression in the brain and body?
Depression is rarely caused by just one factor. According to the team at Eureka Health, it is the combined effect of genetics, brain-messenger changes, hormone shifts and chronic stress that pushes the mood system out of balance and keeps it there.
- Inherited genes alter brain-messenger circuitsIf a parent has major depression, a child’s lifetime risk rises to roughly 30 %, double that of the general population.
- Stress hormones stay switched onHigh cortisol levels measured in saliva are found in about 40 % of people during a depressive episode, showing the body’s stress axis is overactive.
- Brain inflammation plays a supporting roleBlood tests often show C-reactive protein above 3 mg/L in depressed patients, suggesting low-grade inflammation contributes to fatigue and low mood.
- Life events can tip the scaleJob loss, bereavement or chronic illness each raise the odds of a first depressive episode two- to three-fold within the following year.
- Chronic stress can shrink key mood circuitsMRI research cited by Harvard Health shows the hippocampus—the brain’s memory and mood hub—is measurably smaller in many people with depression, and prolonged stress can further suppress the growth of new neurons in this region. (HarvardHealth)
- Women face double the riskDepression is diagnosed in women about twice as often as in men, highlighting the impact of hormonal shifts and social factors on vulnerability. (HarvardHealth)
Which everyday symptoms suggest I might be clinically depressed?
Clinical depression lasts at least two weeks and comes with physical and emotional signs that go beyond normal sadness. “Watch for changes in sleep, energy and concentration—people often miss these early flags,” says Sina Hartung, MMSC-BMI.
- Persistent low mood most of the dayFeeling down or empty on more than 12 of 14 consecutive days meets a core diagnostic criterion.
- Losing interest in once-enjoyed activitiesAnhedonia is reported by 96 % of patients in large surveys and often appears before low mood is noticed.
- Sleep is disrupted in either directionInsomnia or sleeping over 10 hours a day both occur; EEG studies show reduced deep-sleep cycles.
- Energy, focus and decision-making declinePeople with depression make workplace errors at twice the rate of their non-depressed peers.
- Appetite or weight shifts emerge without dietingDepression can push eating patterns in either direction, so clinicians look for unexpected gain or loss that accompanies a drop in mood. (Mayo Clinic)
- Unexplained aches, headaches or stomach trouble can be early cluesHarvard Health notes that many people first seek care for persistent pain or digestive issues, only to discover these physical complaints are part of an underlying depressive episode. (Harvard Health)
What danger signs mean I should seek help right away?
Some situations move depression into an emergency. “Any thought of ending your life warrants same-day medical attention—don’t wait for an appointment,” stresses the team at Eureka Health.
- Suicidal thoughts or planningMore than 60 % of suicide deaths are linked to untreated depression; call emergency services if you feel unsafe.
- Hallucinations or severe paranoiaPsychotic depression affects about 5 % of cases and needs urgent psychiatric care and medication.
- Rapid weight loss over 5 % in a monthMalnutrition and electrolyte imbalances can follow, making hospitalization necessary.
- Post-partum mood collapseUp to 1 in 7 new mothers develop severe post-partum depression; immediate evaluation protects both parent and infant.
- Call 911 or 988 Suicide & Crisis Lifeline immediatelyHarvard Health notes that dialing 911 or 988 connects you to 24/7 emergency support if you have thoughts of self-harm or suicide. (Harvard)
References
- Harvard: https://www.health.harvard.edu/mind-and-mood/depression-symptoms-recognizing-common-and-lesser-known-symptoms
- Mayo: https://www.mayoclinic.org/diseases-conditions/depression/symptoms-causes/syc-20356007?p=1
- PsychCentral: https://psychcentral.com/depression/depression-symptoms-major-depressive-disorder
- WebMD: https://www.webmd.com/depression/guide-chapter-depression-symptoms
Which self-care actions have the strongest evidence for easing mild depression?
Lifestyle changes can lift mood, especially in early or milder stages. Sina Hartung, MMSC-BMI, notes that “consistent, measurable habits trump occasional big efforts.”
- Aerobic exercise for at least 150 minutes weeklyRandomized trials show a 26 % drop in depressive scores with brisk walking or cycling.
- Regular sleep and wake timesKeeping bedtime within a 30-minute window stabilizes circadian hormones linked to mood.
- Omega-3 rich diet or supplementation1 g of EPA/DHA daily improves symptoms in about one-third of people who do not respond to SSRIs alone.
- Brief digital cognitive behavioral therapy10-minute app modules three times a week cut PHQ-9 scores by an average of 4 points in meta-analyses.
- Scheduled social contactSetting two in-person meetups each week counters isolation, a known relapse trigger.
- Mindfulness-based meditation sessions several times per weekMindfulness programs are rated as "likely to be effective" for mild-to-moderate depression and offer a non-pharmacologic option alongside therapy and medication. (Lahey)
- Cutting added sugar lowers depression riskHarvard Health reports a study in which higher refined-sugar intake was associated with a greater likelihood of developing depressive symptoms, suggesting that limiting sweets and sugary drinks may help mood. (HarvardHealth)
What lab tests and treatments might my clinician consider?
Before starting medication, clinicians rule out medical mimics such as thyroid disease and anemia. The team at Eureka Health explains that treatment usually combines therapy, possible medication and monitoring.
- TSH and free T4 to exclude hypothyroidismAbout 4 % of people referred for depression have an underactive thyroid, and treating it often resolves mood symptoms.
- Vitamin B12 and folate levelsLow B12 triples the risk of treatment-resistant depression; supplementation can boost response.
- Selective serotonin re-uptake inhibitors (SSRIs)First-line drugs like sertraline cut symptom scores by 50 % in roughly six weeks for half of users; side-effect profiles differ by agent.
- Evidence-based talk therapiesCognitive behavioral therapy or interpersonal therapy show equal effectiveness to medication in mild–moderate cases and add benefit when combined.
- Follow-up every 4–6 weeksEarly check-ins help adjust dose or switch strategies if improvement is under 20 % on the PHQ-9.
- Complete blood count (CBC) screens for anemia or infectionMayo Clinic lists CBC among routine tests for a depression work-up, because unrecognized anemia or systemic illness can mimic or worsen mood symptoms. (Mayo)
- No single laboratory marker confirms depressionA Lab Medicine review notes that while panels like TSH, B12, and metabolic studies are helpful, there remains "no definitive lab test" for major depressive disorder; laboratories are used mainly to rule out medical mimics and to monitor treatment effects. (OUP)
How can Eureka’s AI doctor support me between visits?
Eureka’s AI-powered doctor chats 24/7, tracks your daily mood scores and flags worrisome trends. “Users tell us they appreciate the immediate feedback while waiting for in-person care,” says Sina Hartung, MMSC-BMI.
- Daily PHQ-2 check-ins with trend graphsSeeing a 3-day upward drift in sadness prompts earlier coping steps and, if needed, a referral.
- Instant triage for suicidal thoughtsIf you type phrases like “I want to die,” the AI offers crisis numbers and alerts an on-call clinician within minutes.
- Medication side-effect diaryLogging nausea or insomnia helps your prescriber fine-tune the dose or timing.
- Guided breathing and grounding exercisesFive-minute audio modules reduce anxiety scores by an average of 30 % immediately after use.
How does Eureka keep my information safe while helping treat depression?
Eureka is designed to be both private and clinically useful. The team at Eureka Health emphasizes that no human sees your data unless you request review.
- End-to-end encryption for all chatsYour mood logs are stored using the same 256-bit standards as major banks.
- Human review only with consentDoctors access your record solely to approve lab or prescription requests you initiate.
- 4.8-star satisfaction among users with mood concernsIn surveys, most say Eureka helped them understand when to seek in-person therapy.
- Free to download and useThere is no subscription fee, lowering barriers for people hesitant to invest in mental health care.
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Frequently Asked Questions
How long do I need to feel sad before it’s considered depression?
Two weeks of low mood or loss of interest, nearly every day, meets the time criterion for major depressive disorder.
Can blood tests diagnose depression?
No single test confirms it, but labs rule out mimicking conditions such as low thyroid hormone or anemia.
Is it normal to feel worse when starting an antidepressant?
Some people have temporary side effects in the first 1–2 weeks; report any increased suicidal thoughts immediately.
Do I have to take medication forever?
Many people use antidepressants for 6–12 months after feeling better, then taper under medical supervision.
Can exercise alone cure my depression?
Regular exercise can treat mild depression and boost standard therapies, but moderate–severe cases usually need additional treatment.
What if my first medication doesn’t work?
About one-third of patients need a dose adjustment or switch; combining meds with therapy raises success rates.
Is depression different from burnout?
Burnout is work-related exhaustion; if symptoms spread to all areas of life and last weeks, depression is more likely.
How quickly can Eureka arrange a therapy referral?
If your answers indicate moderate or severe depression, the AI can send a referral request to a licensed therapist within 24 hours.