Loss of memory is known as amnesia. There are different types and degrees of Amnesia
Types of amnesia
a)Anterograde Amnesia: Anterograde Amnesia is a condition where a person loses all his /her senses. Anterograde amnesia results in a loss of the patient’s ability to create new memories from the time this amnesia was triggered. The patient is often able to recall past histories before he was affected by amnesia – but completely fails to recall recent events.
The precise causes of Anterograde amnesia have still not been comprehended by medical science – as researchers struggle to precisely understand the memory mechanism in our brain.
b) Emotional or hysterical amnesia : Emotional or hysterical amnesia is normally a temporary condition which is caused by psychological problems. This condition usually does not last for a long time.
c)Posthypnotic amnesia: Posthypnotic amnesia is a condition which occurs due to subjection to long periods of hypnosis. In this condition, a patient may not be able to recollect the happenings during the time of hypnosis .
d) Lacunar amnesia : Lacunar amnesia is charecterized by loss of memory relted only to a particular event – creating a type of lacuna in the centers of the brain that records memory(the cortex region). Very little is known about the cause or origin of lacunar amnesia.
e) Transient Global Amnesia: This kind of amnesia lasts for a few minutes and which is normally referred to as short term memory loss. It usually occurs in elderly people.Transient global amnesia involves an abrupt memory lapse which may last anywhere from a few seconds to a few hours. The person suffering from this type of Amnesia does not normally loose consciousness nor are there any other symptoms of impairment.
f) Retrograde Amnesia : Retrograde Amnesia results in memory loss that may wipe out memories for several past years. This loss corrects very fast but may leave leaves enduring gap in the memory. The patient does not remember the events that happened before he/she is affected by this disease. The patient however is normally able to remember the events occurring after this disease.
g)Korsakoff syndrome : This syndrome is a type of amnesia which is mostly associated with excessive and regular consumption of alcohol.
The memory loss may be complete or partial . The two main causes of Amnesia are old age or an underlying mental disorder.