Proportion of Alzheimer’s disease with depression and the dangers Approximately 30-50% of people with Alzheimer’s disease have depression. Depression is a risk factor for Alzheimer’s disease, and depressed patients have an increased risk of developing Alzheimer’s disease. On the other hand, depressive symptoms aggravate the cognitive impairment and daily abilities of Alzheimer’s disease patients and accelerate the progression of the disease. The causes of depression in Alzheimer’s disease are multiple: (1) Early in the course of the disease, most patients still have self-awareness, fear of dementia, and despair; (2) The main pathological change in Alzheimer’s disease, amyloid deposition, can lead to depressed mood and (3) Depression is associated with a decrease in neurotransmitters (pentraxin, norepinephrine, dopamine) in the brain, and in addition to a decrease in acetylcholine, the levels of these transmitters are also reduced or dysregulated in Alzheimer’s disease, causing depressed mood; (4) Cognitive-related brain areas (e.g., frontal lobe, temporal lobe, hippocampus, etc.) are also responsible for mood regulation, and pathological changes in these brain areas in Alzheimer’s disease, in The pathological changes in these brain areas in Alzheimer’s disease cause mood disorders and behavioral abnormalities in Alzheimer’s disease. The symptoms of Alzheimer’s disease with depression are similar to those of the elderly without Alzheimer’s disease, such as depressed mood, reduced interest, pessimism, low self-esteem and despair, fatigue, loss of appetite and sleep disturbance (depressive symptoms) and excessive worry, nervousness, anxiety and fidgeting (symptoms). The difference lies in the fact that many patients have few complaints or are unable to speak clearly about their subjective experiences, which can only be detected through careful observation of the patient’s daily life, behavior and expressions. This requires family members to be attentive in their daily life and communication, and doctors to pay attention to the patient’s body language and behavior when asking questions and examining the patient. Medication principles for Alzheimer’s disease with depression The principles of treatment for depressed patients with Alzheimer’s disease are similar to those for non-demented patients. Tricyclic and tetracyclic antidepressants have significant side effects and are generally not used. Newer drugs such as selective 5-hydroxytryptamine reuptake inhibitors (SSRI) (e.g., citalopram, escitalopram, paroxetine, fluoxetine, sertraline) and multichannel antidepressants (e.g., venlafaxine, mirtazapine) have fewer side effects and are easy to take, so they are generally preferred. However, when choosing new antidepressants, we should also pay attention to the following points: (1) When using drugs, we should choose drugs that have less effect on liver P450 enzymes to reduce drug interactions and improve the safety of drug use. Patients with Alzheimer’s disease often suffer from co-morbidities and use multiple drugs at the same time. When adding antidepressants, attention should be paid to the use of drugs with low interaction with other drugs (such as citalopram, escitalopram, sertraline, etc.). (2) Select drugs according to the characteristics of the patient’s depression symptoms. For patients with anxiety and agitation, choose drugs with certain sedative effects (e.g. paroxetine, fluvoxamine). For patients with indifference and sleepiness, drugs with agitating effects (e.g. fluoxetine) can be used. (3) Pay attention to the small amount to start and slowly increase the dosage. Patients with dementia are generally older, and because of Alzheimer’s disease, the side effects cannot be well described. To be safer, it is recommended to start in small amounts and slowly increase the dosage. New antidepressants reduce amyloid deposition, improve cognitive function and slow disease progression in Alzheimer’s disease The relationship between depression and Alzheimer’s disease and the role of antidepressant medication in Alzheimer’s disease has been widely studied in the last decade or so. It has been found that selective pentraxin reuptake inhibitors (citalopram, fluoxetine, paroxetine) and 5hydroxytryptamine/norepinephrine reuptake inhibitors (venlafaxine) class of antidepressants reduce amyloid deposits in the brain of animal models of Alzheimer’s disease and Alzheimer’s disease patients, increase the levels of monoamine neurotransmitters in the synapses, increase the levels of neurotrophic factors in the brain, and modulate excitatory amino acid receptors, while clinically improving patients’ memory and cognitive abilities, slowing disease progression, and improving the disease process. On top of the existing Alzheimer’s disease treatments (cholinesterase inhibitors and excitatory amino acid receptor antagonists), novel antidepressants are considered as another reasonable and effective therapeutic agent for Alzheimer’s disease.