Often, mental health professionals classify cognitive disorders into two broad categories: those that are irreversible (i.e., not curable) and those that are reversible (i.e., curable). Dementias are irreversible, progressive, degenerative disorders that gradually reduce a person's ability to function in everyday life. A person with dementia cannot regain his or her previous level of functioning, even though some symptoms may be managed through treatment. Examples of irreversible dementias include Alzheimer's Disease, Lewy Body Dementia, and Dementia caused by the AIDS/HIV virus.
On the other hand, the progression of reversible cognitive disorders can be halted by identifying the cause of the symptoms and properly treating the underlying disorder. With appropriate treatment, a person's previous level of functioning can be restored. Examples of reversible cognitive disorders are pseudodementia and delirium, which will be described later.
The types of reversible and irreversible disorders that we discuss is this topic center are classified as "Delirium, Dementia, and Amnestic and Other Cognitive Disorders" in the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; the "gold standard" manual used by mental health professionals to diagnose disorders). We have organized our discussion of different cognitive disorders into these same DSM-IV categories. However, as dementia is the most common cognitive disorder, we will start with a discussion of this condition. Regardless of the diagnosis, the common denominator among all of the conditions discussed here is a significant problem with memory and/or other areas of cognitive functioning that represents an obvious change from the person's previous level of functioning.
Although amnestic disorder (a memory disorder affecting the ability to learn and recall new information, and sometimes, previously learned information or past events) is also included in the cognitive disorders category in the DSM-IV, we will not discuss it here. From our perspective, amnestic disorder more closely aligns with dissociative disorders (a combined disruption in consciousness, memory, identity, and/or perception). So, we will cover amnestic disorders at a later date in another topic center.