Neurological cause of<unk>  is controversial. Even in cases of organic amnesia, where there is lesion or structural damage to the brain, caution must still be taken in defining causation, as only damage to areas of the brain crucial to memory processing is possible to result in memory impairment. Organic causes of amnesia can be difficult to detect, and often both organic cause and psychological triggers can be entangled. Failure to find an organic cause may result in the diagnosis that the amnesia is psychological, however it is possible that some organic causes may fall below a threshold of detection, while other neurological ails are thought to be unequivocally organic (such as a migraine) even though no functional damage is evident. Possible malingering must also be taken into account. Some researchers have cautioned against<unk>  becoming a "wastebasket" diagnosis when organic amnesia is not apparent. Other researchers have hastened to defend the notion of<unk>  and its right not to be dismissed as a clinical disorder. Diagnoses of<unk>  have dropped since agreement in the field of transient global amnesia, suggesting some over diagnosis at least. Speculation also exists about<unk>  due to its similarities with 'pure retrograde amnesia', as both share similar retrograde loss of memory. Also, although no functional damage or brain lesions are evident in the case of pure retrograde amnesia, unlike<unk>  it is not thought that purely psychological or<unk>  triggers' are relevant to pure retrograde amnesia. Psychological triggers such as emotional stress are common in everyday life, yet pure retrograde amnesia is considered very rare. Also the potential for organic damage to fall below threshold of being identified does not necessarily mean it is not present, and it is highly likely that both psychological factors and organic cause exist in pure retrograde amnesia. Comparison with organic amnesia<unk>  is supposed to differ from organic amnesia in a number of ways; one being that unlike organic amnesia,<unk>  is thought to occur when no structural damage to the brain or brain lesion is evident. Psychological triggers are instead considered as preceding<unk> , and indeed many anecdotal case studies which are cited as evidence of<unk>  hail from traumatic experiences such as World War II. As aforementioned however, aetiology of<unk>  is controversial as causation is not always clear (see above paragraph), and both elements of psychological stress and organic amnesia may be present among cases. Often, but not necessarily, a premorbid history of psychiatric illness such as depression is thought to be present in conjunction to triggers of psychological stress. Lack of psychological evidence precipitating amnesia doesn't mean there isn't any, for example trauma during childhood has even been cited as triggering amnesia later in life, but such an argument runs the risk of<unk>  becoming an umbrella term for any amnesia of which there is no apparent organic cause. Due to organic amnesia often being difficult to detect, defining between organic and<unk>  is not easy and often context of precipitating experiences are considered (for example, if there has been drug abuse) as well as the symptomology the patient presents with.<unk>  is supposed to differ from organic amnesia qualitatively in that retrograde loss of autobiographical memory while semantic memory remains intact is said to be specific of<unk> . Another difference that has been cited between organic and<unk>  is the temporal gradient of retrograde loss of autobiographical memory. The temporal gradient of loss in most cases of organic amnesia is said to be steepest at its most recent premorbid period, whereas for<unk>  the temporal gradient of retrograde autobiographical memory loss is said to be quite consistently flat. Although there is much literature on<unk>  as dissimilar to organic amnesia, the distinction between neurological and psychological features is often difficult to discern and remains controversial.
Psychogenic amnesia
Drug-induced amnesia
Excited delirium
Post-traumatic amnesia
Emergence delirium
Posthypnotic amnesia
Transient global amnesia
Memory distrust syndrome