I. What is memory impairment? Memory impairment: A state in which an individual is unable to remember or recall information or skills. It can be a permanent or temporary memory impairment caused by pathological or situational causes. There are several types: 1. Memory enhancement: The patient is able to recall things that he or she was not able to recall before the illness. 2. Memory impairment: The patient has difficulty recalling what he or she experienced in the past, especially events that were linked to a certain time, place and specific context (commonly known as episodic memory impairment). Episodic memory is often in a state of constant change, and the information maintained often changes. Patients with episodic memory disorder have a significantly reduced ability to accept new things. 3. Amnesia: The absence of memory for a particular experience or significant event, mainly manifested as a disorder of recall. There are several different manifestations of amnesia: (1) Parallel amnesia: the inability to recall events that occurred some time after the onset of the disease. The amnesia starts at the same time as the disease. (2) Retrograde amnesia: i.e., failure to recall events at a stage prior to the onset of the disease, but new memories can be formed. This condition is relatively rare. (3) Progressive amnesia: This refers to the progressive development of memory loss as the disease progresses. Most often seen in Alzheimer’s disease. (4) Psychogenic amnesia: It is caused by a heavy traumatic emotional experience, the content of the amnesia is related to some painful experience, and it can be selective content amnesia. (4) Misconstruction: It refers to a false recollection of something experienced in the past, in terms of the time, place and circumstances of its occurrence, and is convinced. 5.Fictionalization: It refers to the patient’s recollection of things that have never been experienced in the past as if they were personal experiences to be described, filling the forgotten memory gap with fictitious facts. 6. Déjà vu syndrome: It refers to the experience of déjà vu of newly perceived things. Second, the relationship between memory impairment and dementia in old age Memory impairment is not necessarily dementia, there are several possibilities as follows. 1. Benign senile amnesia: i.e. age-related memory disorder. It refers to the physiological memory loss brought about by aging in the elderly, without the clinical manifestations of dementia, which is a normal or physiological non-progressive brain aging process. This memory disorder is characterized by difficulty in accurately recalling certain details of events, and in remembering names of people and places. Although sometimes it is forgotten, it can be recalled after a while, or sometimes it is possible to recall the forgotten relevant episodes while forgetting certain secondary contents. The ability to perform daily life or social activities is normal. This is a reflection of the natural law. 2.Mild cognitive impairment (MCI): It is a clinical cognitive impairment state between normal aging and Alzheimer’s disease. It is characterized by the patient’s own complaints of memory impairment and confirmed by an informed person, and may be accompanied by other cognitive impairments (such as attention, visuospatial structure, word fluency, executive function, etc.), but socio-occupational or daily life functions are not affected. Relationship with Alzheimer’s disease: On average, 10-15% of MCI patients convert to Alzheimer’s disease each year; after 3 years, it can reach 50%; after 6 years, about 80%. 3. Alzheimer’s disease: With the aging of the population, the prevalence of Alzheimer’s disease has increased significantly, and about 40% or more of the elderly over 80 years old have different degrees of dementia. The main difference with mild cognitive impairment is that social activities or daily life functions are affected. The following symptoms should be highly suspected if they occur. (1) Memory impairment: including memory loss, misinterpretation, fiction, etc. Early manifestations are highlighted by episodic memory impairment. (2) Mood changes or/and personality changes: confusion, paranoia, fear, agitation, depression, apathy, anxiety or rudeness, etc. (3) Language disorders: prominently manifested by repetitive language. There may also be difficulties in expression, often forgetting simple words or expressing them in inappropriate words, with the result that the words spoken or written are incomprehensible. (4) Loss of interest: Disinterest in daily activities, the ability to sit in front of the television for hours or to drift off to sleep for long periods of time, and a diminished interest in previous hobbies. (5) Visual-spatial cognitive dysfunction: The ability to discriminate spatial orientation between objects, people, scenes and things is diminished. For example, the ability to return home after going out (lost). (6) Calculation disorder: the general subtraction can be judged, such as 100-7=? -7=? -7=?… (7) Distraction: Poor judgment, loss of generalization ability, and distraction may appear in early stages. (8) Social activities or daily life functions are affected: daily chores cannot be completed, such as not turning off the gas after boiling water; there are obvious difficulties in dressing for daily life, such as putting on clothes backwards. When you find that you or your family members have memory impairment, you should make a simple assessment of its nature. If it may be mild cognitive impairment (MCI) or Alzheimer’s disease, you should go to neuropsychological clinic for consultation and treatment as soon as possible.