Amnesia is often referred to colloquially as 'memory loss'.

According to the PNAS, memory can be of two main types: implicit memory, also known as procedural memory, and explicit memory, also known as declarative memory.

Procedural memory refers to the skills you do automatically without having to think much about it like walking, riding a bike or bicycle, etc. It is more like a habit.

Declarative memory refers to retaining facts like participating in a trivia contest, and they need conscious effort to retrieve the information. Implicit memory helps you manage questions of 'how', and implicit memory helps answering questions of 'what'.

When we talk about amnesia, it means some part of the person's declarative memory is affected.

• Anterograde Amnesia: Under this condition, a person's brain fails to form new memories. Someone who suffers from this condition can forget what happened, even an hour from then.

  This can make things extremely confusing and frustrating for the individuals when they cannot recall recent events like where they came from, if they've done a task or not, and what they spoke to with someone just a while ago.

• Retrograde Amnesia: The second and most common type of amnesia is retrograde amnesia which affects a person's ability to recall old memories.

  This can cause anxiety, as they forget important people and events in their life.

Retrograde and Anterograde amnesia can be caused due to the acute and chronic conditions.

According to the doctors of Mayo Clinic, acute causes can be caused by traumatic head wounds or infections and chronic conditions can include neurodegenerative diseases (like Alzheimer's and Dementia) and brain tumours.

Amnesia can also be caused due to thiamine or vitamin B deficiency also known as a warnicke-Korsakoff syndrome.

Amnesia can also result from medical procedures like electroconvulsive therapy and medications like benzodiazepines.

When amnesia is a result of psychological trauma, it is known as dissociative amnesia. There is no information on how psychological trauma causes dissociative amnesia but forgetting the event can be the defense mechanism to remember the distress they had caused.

A person might face difficulty in learning new information during the onset of the condition.

A person may find it difficult to remember past events and information in retrogative amnesia. Other symptoms may include:

• Loss of recent memory

• Problem with short-time memory

• Isolated memory loss

• Difficulty in understanding written or spoken information

• Forgetfuness

• The diagnosis of amnesia requires to get the medical history of the person from their friends and family as well to fill in the possible gaps.

• Blood tests can be helpful in recognising the nutritional deficiencies and infections that may impact memory.

• MRI or CT scans can help identify the structural damage or abnormalities in the brain

In many cases amnesia is temporary and people can regain memory as long as the causes are addressed.

Occupational and cognitive therapy can assist in the recovery process by teaching people methods of organising and storing new information. It may also help them manage their day-to-day life.

Mobile phones and digital devices have become an important part of the treatment as they can remind people with alarms and other reminders as well as a way of storing important information like pictures and videos of close friends and family.

For dissociative amnesia, psychotherapy can help people process the traumatic memory.