Depression (also known as clinical depression, major depressive disorder, or unipolar depression) is a mental disorder characterized by an all-encompassing low mood or sadness accompanied by low self-esteem and by a loss of interest or pleasure in normally enjoyable activities. Major depressive disorder can negatively affect how you feel, think, and behave and can lead to physical problems. It may also cause problems with work, school, your relationships with friends and family members, eating and sleeping habits, energy level, concentration ability, motivation to do things you enjoy previously, body image perception among other issues.
A depressed person may experience one or more of the following: feelings of hopelessness; feelings of worthlessness; fatigue; decreased interest in hobbies or activities that were once enjoyed; difficulty concentrating on tasks; insomnia or hypersomnia (excessive sleeping); appetite changes resulting in weight gain or weight loss; psychomotor retardation or agitation; thoughts of suicide or death.
Causes: The exact cause of clinical depression is unknown. A combination of genetic vulnerability combined with psychological, social and environmental stressors (e.g., trauma) seems to be necessary for the development of the condition. Major life events such as the death of a loved one, divorce/separation/breakup of a relationship are often associated with the onset of clinical depression but most people who experience these events do not become clinically depressed. This suggests that other factors must be involved in order for someone to develop this condition after exposure to a stressful event.
It’s believed that chemical imbalances in the brain may play a role in causing clinical depression. These imbalances involve neurotransmitters (chemicals that help relay messages between brain cells). One theory suggest that people who are clinically depressed have lower levels of certain neurotransmitters like serotonin and norepinephrine while others believe that people with depression have higher levels of corticosteroids (hormones released during times of stress). There is evidence to support both theories but it’s likely that different types/causes/ severities depressions involve different neurotransmitter imbalances. Psychological factors like personality traits (e.g., perfectionism), negative thinking patterns learned during childhood (e.. “I’m not good enough”), cognitive biases (e.g., always expecting the worst), rumination ( obsessively thinking about something bad that happened) can increase someone’s risk for developing clinical depression after exposure to a stressful event . Social factors like isolation/loneliness , chronic stress due to difficult life circumstances( e.. financial difficulties , abuse) , lack social support can also contribute to the development clinical depression .
Genetics: Depression tends to run in families but it’s unclear if this is due entirely to genetic factors or if lifestyle choices made by people who are depressed also plays a role . Studies looking at identical twins who were raised apart suggest that genes play a role since identical twins share 100%of their DNA while fraternal twins only share 50%. However adoptive studies which compare children raised by parents withdepression versus those raised by parents without found no difference suggesting either environment plays little roleor heritability estimates fordepression are overestimated . Neuroimaging studies: Some neuroimaging studies have found differences in brain structure between people with major depressive disorderand those without however it’s unclear if these differences are due entirelyto biology( i.. changes inthe actual structureof neural networks )or partly influencedbyenvironmental experiences( i.. early life adversity leadingto changesin neuronal connections ). Regardlessit appearsthat structuralbrain changesmay predisposean individualto developingdepressive symptoms when facedwithstressful life circumstances . Treatment: Clinical depression is treatable via medication , psychotherapyor both . Antidepressantmedicationcan help correctchemical imbalancesin the brain however they donot work immediatelyand may takeseveral weeksfor full effectsto be felt . Selective serotonin reuptake inhibitors( SSRIs )arethe most commonly prescribed typeof antidepressanthowever thereareother classeslike monoamine oxidase inhibitors( MAOIs )and tricyclic antidepressants( TCAs ). Psychotherapywhichinvolves talkingwitha trained therapistcan help change negativethinkingpatternsand behavioursassociatedwithdepression . Cognitivebehaviouraltherapyis one typeof psychotherapythat hasbeenshowntobe particularly effectiveintreatingclinical depressionsymptoms . Electroconvulsivetherapyis another treatmentoption used mostlywhen other treatmentshavefailed however its useis somewhat controversialdueto potentialside effectslike memorylossand confusion