Cognition is the brain’s ability to retain and use information. A cognitive disorder refers to any medical condition that affects how the brain processes and stores information. It can result in memory loss, faulty perceptions or a combination of both. These disorders can be genetic, environmental, or caused by an injury.
Delirium is a cognitive disorder that appears in episodes and can be temporary or reoccurring. It deteriorates the brain’s ability to process new information or be aware of its surroundings. Hypoactive delirium is when a person who is unaware of his or her surroundings appears to be lethargic or unresponsive, while hyperactive delirium episodes make a person hostile or aggressive. Mixed delirium is a combination of hypoactive and hyperactive symptoms. Delirium has no definitive cause, although stress, alcohol, or medications may contribute to episodes.
While delirium is temporary, it can eventually turn into dementia in some individuals. Dementia is an incurable cognitive disorder that typically causes partial or total memory loss. The disorder also makes learning new information difficult and may inhibit the brain’s ability to evaluate surroundings and make judgments. Dementia can be genetic or caused by brain trauma, stroke, or heart valve infection. Alzheimer’s disease is one of the most common forms of dementia and usually affects people over age 60.
Amnestic disorder, more commonly referred to as amnesia, is a cognitive disorder in which a person either no longer has long-term memories or cannot retain short-term memories. A person with this disorder is usually coherent, unlike some other cognitive disorders. Amnestic disorder can be caused by brain trauma or damage, such as infection, loss of oxygen, or tumors.
A cognitive disorder that can occur in fetuses or young children is mental retardation. It is a condition in which a person has low cognitive abilities due to developmental delays. He or she cannot learn new concepts or function at the same level as other people his or her age. Although the severity of mental retardation can vary, many individuals with the condition do not have the mental skills to safely care for themselves.
Mental retardation is usually diagnosed in children and is typically a condition that they are born with or develop as infants. It can be caused by a variety of bacterial infections while they are in the womb or shortly after they are born. Severe head injuries or nutritional deficiencies can cause an infant to have mental retardation; however, many instances of mental retardation do not have definitive causes.