Looking for missing keys is part of the morning routine for many of us. Sometimes we struggle to remember our email password and recalling the name of an acquaintance becomes as hard as solving a tough riddle. Why does our memory fail us?
Asif Merchant, managing director of Catwalk Worldwide in Mumbai, is yet to figure it out. He makes a lot of notes while talking to someone over the phone and misplaces them. "It turns out to be a big loss," he says. Forgetting to return a call gives him guilt pangs. "Sometimes I even forget to take money while leaving home," rues Merchant. The 45-year-old is learning to live with his absentmindedness, though his family broods over it a lot.
Memory problems worry multitasking super moms, too. "I broke my leg two years ago. Now I just can't remember whether it was the right one or the left," says a friend who has been juggling her home and career. Some keep worrying about whether they had unplugged the iron box or turned off the stove even after reaching office, while some others forget to take their packed lunch while leaving home for office. Forgetting to take out clothes from the washing machine and fish from the freezer is perhaps too common.
You might argue that your hands are full, you have a hundred things to do, but do those casual slips and small omissions point to a graver cause? "It depends on why you forget," says Dr Jamuna Rajeswaran, associate professor at the department of clinical psychology at National Institute of Mental Health and Neuro Sciences (Nimhans), Bangalore. “Forming a memory involves integrating different sensory experiences (encoding), converting short-term memory into long-term memory (consolidation), and recalling stored information (retrieval). Sometimes you may have trouble retrieving information just because you were inattentive while the sensory experiences were getting encoded into the brain. Meanwhile, memory problems can occur due to a faulty component of any one part of your memory system. Our memory tests help identify such problems."
Memory lapses found in younger patients are often caused by psychological causative factors rather than degenerative problems. "One can have pseudo-dementia due to depression, stress or anxiety," says Dr Mathew Abraham of Indira Gandhi Cooperative Hospital, Kochi, where the country's first memory clinic started functioning in 1999. "We find out whether the patient makes mistakes with money or directions as Alzheimer's patients do. Even how one cooks sambar gives a lot of clues about one's cognitive functions, as it involves a series of sequential things," says Abraham. "We rule out chances of infections like HIV, tuberculosis, meningitis and tumours, which can also sometimes lead to memory loss."
Memory, “a stored pattern of synaptic connections between neurons”, is one of the most fascinating functions of the human brain. Without memories, we are no longer what we were. Without memories, we lose our selves, our identity.
Your iPad or PC may look humble when juxtaposed against the human brain. The human brain has around a hundred billion neurons and, together, they can make around a thousand trillion synapses whereas the memory capacity of a personal computer is just about 100 billion bytes (100 GB).
But do memories become obsolete when multiple gadgets take over as extensions of the brain? “It is not likely to happen,” says Dr Shiv K. Sharma, additional professor and scientist at the National Brain Research Centre in Manesar, Haryana. “We need memory not only to remember facts and figures, but also for a smooth sailing in life. It helps us adapt to a particular environment. Memory is vital for decision-making and our day-to-day functioning.” So you take a call on whether to say ‘hi' to your neighbour, based on the experiences you have had with him, which are stored in the brain in the form of memories.
But, sometimes, memories fly away from us. There can be many reasons for memory lapses and disorders. “Mid-life stress is a risk factor for dementia in old age,” says Dr Vinay Goyal, associate professor of neurology at All India Institute Of Medical Sciences, Delhi. Studies have shown how a major episode of depression or prolonged stress leads to dementia. “Stress affects memory in multiple ways,” says Sumantra Chattarjee, professor of neurobiology at the National Centre for Biological Sciences (NCBS) in Bangalore. “Due to stress, your cognitive functions will go downhill and memories of facts and events will get impaired. So you may have difficulty in remembering phone numbers and such things,” he says. “This is because the neurons in the hippocampus, which codes and processes information from sensory organs, shrink and lose their branches as a result of stress.”
Animal and clinical studies done by Chattarjee and his colleagues throw more light on the effects of stress on memory. They showed that even as the hippocampal neurons shrink, those in another part of the brain called the amygdala, which is the hub of neural connections related to emotional events, grow in size because of stressful experiences. “This is the reason why we have vivid memories of stressful and fearful experiences even after the stress is over, which leads to further anxiety and fear. In short, the hippocampus crumbles and the amygdala becomes stronger due to stress," adds Chattarjee.
Even very brief, yet severe, stress caused by sexual abuse, violence, rape or accidents can have a detrimental effect on memory. Social stress also contributes to memory problems. “Suppose you have a very hierarchical system in your office and you have to put up with your seniors. This moderate level stress, which goes on for months or years, can result in permanent damage to your amygdala. Our lab experiments show how animals which are lower in terms of social ranks get bullied around by stronger and bigger ones and end up having problems with their amygdala," he says.
Experts point out that stress can be one of the factors responsible for the increasing number of dementia (memory impairment) patients in India. According to the Dementia India Report 2010, 3.7 million people in the country have dementia. The numbers are expected to double by 2030.
“Dementia is basically an age-related disease and the increase in the number of patients has much to do with increased longevity,'' says Dr P. Satish Chandra, director of Nimhans. “At least 2.1 million of the dementia patients in the country are women. The higher prevalence among women could be due to the fact that they live longer than men."
Sukla Bhattacharya, 76, of Kolkata, was diagnosed with Alzheimer's disease, the most common form of dementia, in 1994. Her 86-year-old husband, Brigadier S.P. Bhattacharya has been taking care of her with single-minded devotion. Bhattacharya used to read out fairy tales to Sukla because these stories, he feels, used to comfort her.
As the disease progressed gradually, Sukla had severe memory problems. “The woman who could prepare and serve food for 25 people single-handedly found it hard to even serve three items of breakfast in a sequence,” he recalls. “By 2000, she was unable to read and write. She couldn't even dial a telephone number.”
Things got worse in the following years. “Sukla started treating me like a stranger. She couldn't recognise me even on our 50th wedding anniversary. Once, on seeing a mirror reflection of both of us together, she stood still for a few minutes looking confused," says Bhattacharya. This was followed by a violent phase. “I had to tie her hands up to prevent her from hurting herself and me. To stop her from spitting around, I used to make her wear a mask."
When everything else fails, Bhattacharya employs his ingenuity. Once Sukla came to Bhattacharya yelling, “I want to commit suicide!” Bhattacharya, who knew how much she loved the movie Sholay, rekindled those memories and she started laughing. Sometimes he would pacify her by talking to her about Amartya Sen, who was her batch-mate at Presidency College, Kolkata, and other friends with whom she was very close to.
Of late, Sukla has become very quiet. She sleeps most of the time and goes for walks six times a day like an obedient child. She had a “phenomenal memory'' and she used to win prizes for quiz competitions during their Army days. Bhattacharya feels that if it could happen to Sukla, it can happen to anyone.
Most of the scientists working on Alzheimer's disease consider that the accumulation of an abnormal protein called amyloid beta plaque between neurons in the brain is the main culprit. Studies at Nimhans show that neurodegeneration accounts for 58 to 60 per cent of dementia cases. “Twenty per cent of the cases are of vascular dementia, which is caused by diabetes, hypertension, obesity and smoking," says Chandra. “Infections like tapeworm infection and TB of the brain constitute 17 per cent. In the third type, the brain shrinks and loses its volume. And last is miscellaneous variety due to thyroid problem.” Experts point out that India could be heading for a dementia epidemic.
There are different ways to test memory. "The tests we use at Nimhans assess various aspects of memory such as short term memory, encoding, as well as long-term retrieval. Some assess verbal memory while others evaluate the visual features of memory,” says Niranjana Bennett, a PhD scholar at the institute. “Subjective complaints of memory can be objectively defined by these tests, as norms were developed at Nimhans. The performance of patients with traumatic brain injury, mild cognitive impairment, dementia, stroke, tumours and a host of other conditions are, therefore, compared with these norms, to ascertain if there are indications of memory deficits.”
As a significant portion of the ageing population in the country is struggling to rekindle memory, there are people who are overburdened by them. A 41-year-old administrative assistant from California, who is referred to in medical journals as AJ, remembers each and every day in her life since age 11, as if in a movie. She doesn't make any conscious effort to memorise them. She remembers her trips to the provision store and what the weather was like on a day decades ago. She still has vivid memories of the day a man she had a crush on telephoned her—it was on August 3, 1986 at 12.34 p.m. Good memories do comfort her a lot, but bad memories don't spare her either. So what most people would consider a gift has become a “burden'' for her, and she yearns to be “a simple person, without all that stuff in her head''.
While AJ's extraordinary memory is for autobiographical details, Delhi-based 12-year-old Rishikesh S., who is autistic, is exceptionally good with dates and days. “He can remember calendar dates and days for the last five years,” says Dr Sameer Malhotra, head of the department of Mental Health and Behavioural Sciences, Max Healthcare, Delhi, who has been treating him for behavioural problems.
Rishikesh used to be restless and his parents were worried about his fidgety behaviour and outbursts. During the treatment, Malhotra and his team observed that Rishikesh was quick in picking up musical notes. “Alongside the treatment for behavioural problems, we counselled Rishikesh's parents to encourage him with his uncommon memorising abilities. Now he can play the keyboard and tabla quite well,” smiles Malhotra.
Memory researchers say that emotion has a profound effect on memory, and memories having emotional content stay longer in our minds. And, women generally are known to have better emotional memory than men.
Sonal Barjatya, 31, of Indore, hasn't celebrated her birthday for the last 14 years, as memories of a bitter experience she had on her 17th birthday still haunt her. Sonal's father wanted her younger sister to be a singer. So her mother and sister shifted to Mumbai.
Sonal was to join them and her father wanted to celebrate her 17th birthday in a grand way, as he thought it would be her last birthday in Indore. “Everything was okay, when suddenly one of my aunts came to me and asked why my dad threw such a big party when we were going through financial problems,” she recalls. “She started blaming me ruthlessly and kept saying that it was all because of me. I was completely broken.”
That was the last time Sonal celebrated her birthday. “Even today, I feel bad when my birthday approaches. I can't face my birthday. I want the memory of that day to disappear," she says, with tears in her eyes.
Sonal now stays in a posh apartment in Bangalore, takes tuition classes for school children. Though she has not been able to get rid of her bitter memories, she advises the children on how to sharpen their memory.
“Be attentive in class. After reading a lesson, take a break and read it again. This helps form long-term memories, instead of reading it several times one after the other,” she reminds them. “And sleep well before exams, as memory consolidation happens during sleep.”
Some names have been changed.
Museum of memories
There are 350 samples of the human brain, shrouded in silence. Dr S.K. Shankar, emeritus professor and principal coordinator of the Human Brain Tissue Repository at the National Institute of Mental Health and Neuro Sciences, showed me around the brain museum, the only one of its kind in the country. The brains on display in formalin-filled jars reminded me of the walnuts in the transparent plastic containers in my kitchen.
But they are not as simple as they seem. Each brain has about a hundred billion nerve cells. New synaptic connections between the neurons are created whenever a memory is formed.
"Our knowledge of memory formation and memory disorders has been derived mainly from patient studies,” said Shankar. He then held out a jar containing the brain of an Alzheimer's patient. “This brain weighs only 800gm, whereas a normal adult human brain may weigh anywhere between 1,000 and 1,500gm,” he said. “Due to Alzheimer's, it has shrunk as it has lost all its neurons.”
The museum has samples of brains affected with various types of dementia, like fronto-temporal dementia and Parkinson's disease with dementia. Shankar also showed me a jar labelled ‘stroke'. Looking at the brain sample, he was reminded of a patient who had multi-infarct dementia associated with hypertension (high blood pressure). “His neuronal connections between areas involved in memory formation were lost. Because of this the neurons connected to those cables underwent degeneration resulting in memory loss and dementia,” he recalled.
Having worked as a neuropathologist for 32 years, Shankar knew many of the patients whose brain samples he had collected for the museum personally. He works till 8 p.m. at the museum, surrounded by those memories.