Madhav (name changed) couldn’t understand what was happening to him. The 19-year-old college student was in the midst of a test paper when he found that his right hand wasn’t working. Some days later, he couldn’t remember if he had appeared for his mid-term examinations. He would ask his professors and friends repeatedly. He would open his e-mail inbox and forget what he was looking for.

Madhav, it was later diagnosed, suffered from anterograde amnesia. The term will gain currency once Aamir Khan’s coming film Ghajini hits theatres later this year. The Bollywood actor, who takes pains to reinvent himself through innovative roles, will pay tribute to a patient who furthered the cause of medical science.

The legendary patient, known as Henri, had anterograde amnesia — a disorder which revolves around a person’s inability to form fresh memories. Henri’s name was revealed for the first time last year — marking 50 years of the diagnosis of the disease. He is now 83 and lives in the US.

Anterograde amnesia is a devastating disorder that makes people lose their memory. They fail to recollect a development minutes or hours after its occurrence, depending on the severity of the problem.

“It is really difficult to say how prevalent anterograde amnesia is in India as there hasn’t been any study on this,” says Roy Daniel, head of neurology at the Christian Medical College and Hospital, Vellore. “But out of nearly 300 cases that come to us every month, 10 suffer from anterograde amnesia.”

Anterograde amnesia is different from retrograde amnesia, in which memories of the past are partly or fully wiped out. Anterograde amnesiacs have their memory of events that occurred in the past intact — but only until the onset of the disease. It is caused generally by accidents that involve head injuries or are left behind by diseases such as brain tumours or viral brain fevers. A cerebral stroke led to Madhav’s disorder.

Surgeries to remove a tumour in the brain or for treating epilepsies can also lead to anterograde amnesia if areas of the brain involved in storing new memories have been removed as part of the treatment. Prolonged overdose of certain medicines is also known to cause the disorder.

Henri, the first-ever recorded case, for instance, became an anterograde amnesiac because of brain surgery. He had been suffering from severe seizures and loss of consciousness since he was 16. On the other hand, the protagonist portrayed by Aamir Khan in Ghajini, loosely based on the 2001 Hollywood movie Memento and a remake of a hit Tamil film, sustains a brain injury after an attack by thugs. The film captures the tryst of the protagonist who, despite his fickle memory, tracks down the killers of his wife.

Those who suffer from severe anterograde amnesia soon forget who they met or what they ate, and are incapable of recollecting what they did just a few moments before, says N. Jamuna, a clinical psychologist at the National Institute of Mental Health & Neuro Sciences, Bangalore. One of her patients, a 45-year-old engineer called Reddy (name changed), developed the disorder following a road accident that led to a brain injury when he was on a pilgrimage to Tirupati two years ago. Reddy, who ran a business firm with other family members, recovered subsequently and looked hale and hearty, Jamuna recollects.

But then his brothers found that strange things were happening. Their company got into financial and legal trouble as Reddy would write out cheques or dole out cash at will and then forget all about them. “It was then that they brought him to the institute. Now, after two years of counselling and mental exercises, he has recovered nearly 80 per cent. Beyond this doesn’t seem to be possible,” Jamuna observes.

Ramesh (name changed) had a similar experience. A brilliant scholar, he was travelling abroad when he fell unconscious at an airport. A test showed a brain tumour, which was subsequently removed.

“He came back home and resumed work. He then noticed that he was extremely forgetful. While he could recollect all his work and studies prior to the incident, he could not remember day-to-day events. The only way he could manage his work was by constantly writing down events, appointments and schedules in his diary and constantly looking at his diary to remind himself of the many tasks he had planned for every day,” says Daniel.

Currently, there is no known way to repair the brain damage which causes anterograde amnesia. However, diagnosis has now become easier with new imaging techniques such as magnetic resonance imaging and computed tomography (CT scan) becoming commonplace, says M.C.Maheswari, a consultant neurologist at the Vidyasagar Institute of Mental Health & Neurosciences, New Delhi.

“The disorder is not very uncommon these days with so many road accidents resulting in brain injuries,” he says. Sometimes the blank out lasts only a few minutes. If it is severe, it may last for years and some patients may never fully recover, Maheswari says.

According to neurologists, memories are of two kinds. Declarative memory is acquired through learning and knowledge and can be autobiographical. Like an autobiographical play, it is a creative construction put together from past events, fears, wishes and conflicts. Then there is procedural memory, which is more about skills, such as driving, cycling or swimming — also called ‘know how’ memory.

Amnesia normally affects declarative memory. For instance, an anterograde amnesiac will not forget how to drive, but may forget directions given to reach a place. Similarly, they may find it difficult to carry out a job, as they may forget events. Henri couldn’t remember for many years which of his parents had died.

Many patients have been able to find a way out by simply writing down things that they need to remember. “But learning new things is certainly a difficult thing for them, says Sumantra Chattarji, who studies neurobiology of learning and memory at the National Centre for Biological Sciences in Bangalore.

Advances in neurosciences and sophisticated diagnostic tools have helped scientists and doctors pinpoint what regions of the brain are involved in the disorder. But scientists have so far failed to find a cure for anterograde amnesia because they know very little about how memories are formed.

“We know that as memories are formed certain networks of brain cells are either strengthened or weakened. But still there are several open questions about the formation of memory,” says Shuba Tole, a neurobiologist at the Tata Institute of Fundamental Research, Mumbai.

But it is not that scientists do not have a glimmer of hope. Researchers at the Post Graduate Institute of Medical Sciences (PGI), Chandigarh, recently found that when rats, on an overdose of drugs that cause amnesia, are fed an extract of Brahmi, an Indian herb used in Indian systems of medicine, they showed an improvement. “But it is too early talk about its therapeutic significance,” says Akshay Anand, a PGI scientist involved in the study.

Till a cure is found, anterograde amnesiacs may have to go through what Henri had once famously said: “Every day is alone by itself, whatever enjoyment I have had, whatever sorrow I have had.”