摘要With the fast-growing aging population, dementia has become a health priority. However, in the past, medicine was largely dealing with physical disorders, and not enough knowledge and experience have been accumulated for mental health. The main and first symptom of this disorder is the loss of memory; hence, understanding the hippocampal formation is the key to tackling dementia. In 2007, a milestone book titled"Hippocampus Book"was published. One of the authors/editors is the 2014 Nobel Laureate in Physiology and Medicine, Professor John O'Keefe. It is a MUST-READ encyclopedia about the hippocampal formation, for those who wish to commit them-selves to helping the patients with dementia. The formation consists of the hippocampus, entorhinal cortex, subiculum, presubiculum, parasubiculum, and dentate gyrus. The hippocampus is further divided into CA1, CA2, and CA3. The entorhinal cortex is the gateway of receiving all sensory information from the neocortex, while the subiculum is the exit for the efferent projections to the neocortex. Memory is divided into short-term and long-term memory. The former does not require protein synthesis while the latter does. The electrophysiological activities of creating these memories are short-term potentiation and long-term potentiation respectively. In most cases, the entorhinal cortex is the first structure to be damaged, and even short-term memory cannot be created. However, all except spatial memory are stored in the neocortex. Damage to the hippocampal formation would not affect the storage and retrieval of memories. Hence, past memories may remain intact in the early phases of the disorder. This devastating progressive disease has no cure. However, the highly plastic hippocampal formation may offer us some hope. It is the responsibility of the pharmaceutical industries to develop new drugs. Clinicians should add their efforts to the endeavor. The author would suggest that they explore insulin-like growth factors, brain stimulation, cell transplantation, and animal-assisted therapy to find some innovative solutions to help patients with dementia. As the current status of neuroscience stands, the animal-assisted therapy seems to stand out among all methods. It alleviates symptoms and stabilizes the ailment.