Geriatric depression is one of the three major psychiatric disorders of old age (dementia, depression, neurosis), and still belongs to the disease unit of depression taxonomically, but shows specificity in epidemiology, etiopathological mechanisms, clinical manifestations, treatment and prognosis. Epidemiology: WHO data show that the prevalence of depression accounts for about 3% of the population, while the prevalence of depression in the general population over 65 years of age accounts for more than 10%, much higher than the younger population, and monophasic depression is absolutely dominant, with up to 30% of inpatients. Etiology and pathological mechanisms: ①Biochemical: the level of monoamine neuromediators in the brain of the elderly is reduced, such as 5-hydroxytryptamine, dopamine, norepinephrine and their metabolites; the loss of adrenergic neurons leads to a decrease in amine storage and synthesis; and monoamine oxidase activity is increased. ②Psychosocial factors: the elderly encounter more adverse family and social factors events, which can easily induce depression. (③) Somatic factors: elderly people often suffer from various physical diseases such as diabetes, hypertension, coronary heart disease, etc., and some drugs taken after suffering from physical diseases may also lead to depression. Clinical manifestations: The main manifestations are slow thinking, depressed emotion and psychomotor inhibition, but there are the following characteristics: ① Agitation: excessive movement or speech without psychomotor inhibition when depressed emotion; ② Retardation: behavioral retardation, characterized by slow and lack of random movement, accompanied by reduced expression and slow thinking; ③ Invisibility: 70% of the complaints are based on physical discomfort, and mood disorders are easily ignored; ④ Delusional: suspicion and paranoia are the main symptoms of depression. ④Delusional: mainly suspicious delusions and delusions of nothingness; ⑤Pseudodementia: rapid onset, early overall reduction in intelligence level, but good effect by antidepressant treatment; ⑥Suicidal tendency: much higher than the young population, less aura performance, and high success rate of suicide. Treatment: (1) Physical therapy: ① Pharmacotherapy: use drugs with fewer adverse effects, shorter half-life, fewer active metabolites, and fewer drug interactions, such as the new antidepressant SSRI citalopram, etc. ② Modified electroconvulsive therapy (MECT): it can be preferred for patients with major depression, refusal to take medication, and serious suicidal attempts or behaviors, and is generally safer. (③Other: such as exercise therapy, light therapy, repetitive transcranial magnetic stimulation (rTMS) therapy, etc. (2) Psycho-behavioral therapy: preferred for mild and moderate depression. There are mainly cognitive behavioral therapy, behavioral therapy, supportive psychotherapy, as well as music therapy, occupational therapy, social skills training, vocational skills training, role change training and other rehabilitation treatments. (3) Social therapy: life care, community services, etc. Prognosis: Most of them have long disease duration, easy to relapse and high mortality. There are reports of three-year follow-up: 1/3 recovery, 1/3 relapse, 1/3 chronic prolongation.