A follow-up study of 149 patients with PD showed that the proportion of patients who met the criteria for dementia was 48%, and the incidence of hallucinations and depression reached 50%; at 20 years of disease, the patients’ neuropsychiatric symptoms further progressed, and the incidence of dementia could be as high as 83%, and the incidence of hallucinations reached 74%. In addition, the incidence of anxiety and affective apathy were above 40%. The prevalence of psychiatric disorders varies widely from 25% in community-based samples to 50% in clinic-based samples, and psychiatric symptoms may have been one of the reasons for patients to present for care. According to the Braak theory of disease progression, PD starts long before motor symptoms. The disease begins in the dorsal nucleus of the vagus nerve in the lower medulla and the olfactory bulb, and in the early stages (Braak stage 1), the main manifestations are insidious non-motor symptoms such as autonomic dysfunction and olfactory hyposmia. As the disease progresses, the lesions gradually involve the blue spot, substantia nigra and middle cortex, then sleep disorders and depression disorders appear (stage 2). The neuropsychiatric symptoms of PD can be present throughout the disease. 02 manifestations of psychiatric symptoms of PD 1. Depression The types of depression in PD can be divided into three categories: reactive depression, endogenous depression, and fluctuating depression. Reactive depression is a reaction of patients when they are informed of the disease; endogenous depression is a symptom of PD itself and has the basis of structural lesions of the nervous system involved in PD disease itself, and this type of depression can appear in all phases of PD disease; fluctuating depression is easy to be ignored. For PD patients, motor symptoms can not only fluctuate, but depression can also fluctuate, and it is part of the end-of-agent phenomenon, and measures targeting motor fluctuations are equally effective for fluctuating depression. Compared to general depression, depression in PD is not fundamentally different, but there is a difference in the proportion of symptoms occurring between the two. In terms of affective indifference, delusions and suicide attempts, the incidence of PD-related depression is lower than that of general depression, indicating that depression in PD patients is predominantly mild to moderate. Another difference is that depression in PD patients is more difficult to treat and the efficacy of using antidepressants is not good, with refractory depression accounting for 22% of depressed patients with PD, compared to 10% of refractory patients with general depression. Depression in PD patients has a great impact on the quality of life, but people do not pay enough attention to it. A survey in the UK showed that the incidence of depressive symptoms in early PD patients is high and is often an important factor prompting patients to seek medical attention, but often receives little attention, making the quality of life of patients is not better. 2, anxiety PD patients have little difference in anxiety compared to ordinary anxiety patients, mainly manifested as generalized anxiety, panic disorder, social terror, square terror and non-specific anxiety, compared to patients with panic disorder. Generalized anxiety is influenced by many factors and may include affective apathy, hyperventilation, tremor, thermoregulatory disorders, and autonomic impairment. Among them, autonomic impairment and tremor tend to be more common and susceptible to motor symptoms, while apathy is not affected by motor symptoms. 3, emotional indifference emotional indifference is a mental state of reduced emotional response, divided into three categories: behavioral, cognitive and emotional, the main core is a lack of motivation. The cognitive type is characterized by lack of interest in new things and indifference to other people’s problems, accounting for most of the cases; the behavioral type is followed by lack of aggressive and creative behavior and dependence on other people’s activities; the emotional type is characterized by bland emotions and lack of emotional response to objective or negative events. Affective indifference can exist independently or often occurs simultaneously with depression. 4, Psychotic symptoms In addition to the above, psychotic symptoms such as hallucinations, delusions, illusions and false perceptions of existence are also more common. In addition, although the incidence of impulse control disorders is low, the incidence of impulse control disorders in elderly patients gradually increases as the disease progresses, mainly manifesting as overeating, hypersexuality, compulsive shopping and gambling, in addition to impulsive-compulsive behaviors such as Punding (stereotyped, repetitive purposeless behavior) and dopamine dysregulation syndrome, mainly manifesting as compulsive overdose of anti-PD drugs. There are mechanisms of impulse control disorders, with alterations in the dopamine system, ventral striatum, and cortex seen on imaging, as well as gender and age influencing the specific manifestations of impulse control disorders. Clinical medications are also relevant, as dopamine agonists may induce impulse control disorders, and smoking history, lifestyle habits, and family history may also have an impact.03 Treatment of Psychiatric Symptoms in PD Current guidelines recommend three medications for the treatment of depression in PD. The first is the drug pramipexole for PD itself, which has a definite anti-PD depressive effect and can be used for PD depression treatment (B-level recommendation). The antidepressants paroxetine and venlafaxine extended-release capsules have a significant difference in efficacy compared with placebo and can be used for PD depression treatment (level B recommendation). In addition, SSRI antidepressants, including escitalopram, lack sufficient evidence to prove their efficacy, but they can be considered for the treatment of depressive symptoms associated with PD due to their mild side effects (U recommendation); selagiline also has potential antidepressant efficacy in PD patients (U recommendation). Treatment of PD with anxiety lacks sufficient evidence-based medical evidence, and anxiety in PD patients is usually accompanied by depression, so antidepressant treatment can improve patients’ anxiety symptoms, and benzodiazepines, such as lorazepam or diazepam, can be used for moderate anxiety (U-level recommendation). In addition, similar to the general population, SSRI drugs can be used for the treatment of panic attacks, social fears and obsessive-compulsive symptoms in PD (U-level recommendation). In the treatment of PD with affective indifference, a recent foreign trial using piribedil 300 mg/d showed that it significantly reduced PD indifference scores. It is important to note that the maximum dose of piribedil is 250 mg/d, and the dose used in this study was beyond the domestic dose. Clozapine is recommended for the treatment of psychotic symptoms in PD. It is effective in PD patients with visual hallucinations, delirium and other psychotic symptoms, and does not aggravate PD symptoms, and has even been shown to improve motor symptoms to some extent, but it has the side effect of granulocytopenia and therefore needs to be checked regularly (Grade B recommendation). It should be noted that olanzapine, a common psychiatric drug, is not recommended because it significantly aggravates extrapyramidal symptoms and does not improve psychotic symptoms in PD patients (Grade B recommendation). A recent phase III clinical trial (lasting 6 weeks) of a new drug, Pimavanserin, a 5-HT 2A antagonist that does not affect the dopamine system per se, showed that the drug improves psychiatric symptoms in PD and does not exacerbate motor symptoms in PD itself, and has a better effect.