Stagnant thinking is a common symptom of dementia. Stagnant thinking means that associations are not easily developed, showing obvious inertia and always dwelling on the same problem. Early detection and treatment are necessary. So what are the tests that need to be done? 1, neuropsychological test Simple Mental Scale (MMSE): concise content, short measurement time, easy to be accepted by the elderly, is the most common scale to measure the degree of intellectual impairment of the disease in clinical practice. The total score of the scale is related to the level of education. If the score is ≤17 for illiteracy, ≤20 for elementary school, ≤22 for secondary school, and ≤23 for university, it indicates the presence of cognitive impairment. Further detailed neuropsychological tests should be performed to assess various cognitive functions including memory, executive function, language, use and visuospatial ability. Assessment of activities of daily living (ADL): For example, the Assessment of Activities of Daily Living (ADL) scale can be used to assess the degree of impairment in patients’ activities of daily living. This scale has two parts: the first is the physical self-care ability scale, which measures the patient’s ability to take care of his or her own life (e.g., dressing, undressing, combing hair, and brushing teeth); the second is the tool use ability scale, which measures the patient’s ability to use the tools of daily living (e.g., making phone calls, taking the bus, cooking for himself or herself). The latter is more susceptible to cognitive decline early in the disease. Assessment of behavioral and psychiatric symptoms (BPSD): including the Behavioral Pathology Assessment Scale for Alzheimer’s Disease (BEHAVE-AD), the Neuropsychiatric Symptom Inventory (NPI), and the Cohen-Mansfield Agitation Questionnaire (CMAI), which often requires baseline assessment based on information provided by the informant, not only to detect the presence or absence of symptoms, but also to be able to evaluate symptom frequency, severity, and burden on Repeated assessments can also monitor the effectiveness of treatment. Laboratory tests for dementia Patients suspected of having organic dementia should undergo selective lumbar puncture, blood biochemical tests, electroencephalography, brain ultrasound, isotope brain scan, cranial X-ray, pneumoencephalography, cerebral angiography or CT. The first step is to understand the age of onset of dementia, which is relatively old. The symptoms of dementia caused by cerebrovascular disease fluctuate. 4. Physical examination Dementia itself does not have fixed signs, but the primary disease can often show certain signs. Patients with paralytic dementia may have uneven pupils, two then unequal size, and ayiro pupils. Patients with senile psychosis mostly have corneal age rings, gray hair and skin wrinkles. Lead lines are visible in the gums of patients with lead poisoning, etc. Certain primary illnesses are often accompanied by certain neurological signs.