[Hikikomori and locked-in syndrome]

Visual agnosia is a condition characterized by the inability to recognize visually presented objects despite having normal vision. For instance, a person with visual agnosia can describe the shape and color of an object but cannot identify or name it. This impairment does not affect their visual field, acuity, color vision, brightness discrimination, language, or memory. An example of this condition in a social setting is someone at a dinner party asking for "that silver thing with a round...

Dissociative amnesia is a complex psychological condition that manifests as an inability to recall personal information, often tied to traumatic or stressful events. Unlike general amnesia, individuals with this condition retain the ability to perform routine activities and procedural tasks, such as operating a phone or navigating public transportation, yet experience profound gaps in autobiographical memory. These lapses may encompass significant life events, such as suicide attempts or...

Dementia is a collective term for cognitive disorders primarily affecting memory, thinking, and reasoning. It is not a specific disease but a syndrome, with Alzheimer's disease being the most common cause, accounting for approximately 60-80% of cases. Other types include vascular dementia, Lewy body dementia, and frontotemporal dementia. Dementia affects millions worldwide, particularly older adults, though it is not a normal part of aging.
The progression of dementia is generally gradual....

Somnambulism, commonly known as sleepwalking, involves individuals engaging in activities ranging from simple walking to more complex behaviors such as driving. Sleepwalking typically occurs during the slow-wave sleep stages 3 and 4 early in the night when the person is not dreaming, contradicting the myth that sleepwalkers are acting out their dreams.
Factors that increase the likelihood of sleepwalking include sleep deprivation and alcohol consumption. Contrary to common beliefs, it is safe...

Dissociative Identity Disorder (DID), previously termed multiple personality disorder, is a complex psychological condition characterized by the presence of two or more distinct identities or personality states. Each identity exhibits unique patterns of behavior, voice, and mannerisms and may possess separate memories and emotional responses. The alternating control between identities can result in memory gaps and challenges in recalling daily activities, often exacerbating the individual's...

The meaning of illness is individualized to each person who experiences an alteration in health. In contrast, disease is a medical term indicating a pathological change in the structure and function of the body or mind. It is a condition that has specific symptoms and boundaries.
An illness is a response to a disease in which the person's level of functioning is changed compared with a previous level. The general classification of illness includes acute and chronic.
Acute illness is severe...