Tuesday, August 7, 2012


Dr Sudhir Kumar MD (Internal Medicine), DM (Neurology)
Senior Consultant Neurologist
Apollo Health City, Hyderabad

Memory is one of the most important functions of human brain. A good memory is important in all stages of life. A child’s learning ability and scholastic performance depends a lot on his memory. Similarly, in adults, a good memory is vital to perform the job well. Normal memory is also required in day-to-day life activities. For example- a housewife depends on her memory of recipes to prepare a good meal. After having seen the importance of memory in our lives, it is easy to appreciate the hardships one would go through if there is memory loss. Memory loss, along with impairment of other brain functions, is also referred to as dementia.
Causes of memory loss
Memory loss occurs due to a dysfunction in brain. The commonest causes of memory loss are:
  1. Alzheimer’s disease (AD): AD is the most common cause of dementia in the world. It is a degenerative disease of the brain and commonly affects older people.
  2. Brain strokes- Strokes occur due to a lack of blood supply to the brain. These occur in people with risk factors such as smoking, diabetes, high BP and high cholesterol.
  3. Infections- such as HIV, syphilis, brain fever (meningitis, encephalitis)
  4. Nutritional deficiencies- such as vitamin B12 deficiency
  5. Endocrine disorders- such as hypothyroidism (lack of thyroid hormone)
  6. Head injury
  7. Brain tumors
  8. Stress and depression.
Stress and memory loss
Mental stress, anxiety, depression and other psychiatric disorders are important causes of memory loss today. In anxiety and stress, there is no structural damage of the brain (as compared to AD or brain strokes, where structural damage occurs). Therefore, a bran scan (CT or MRI) is often normal in stress-related memory loss; however specific findings on MRI brain occur patients with AD and brain strokes.  
Biochemical basis of stress-related memory loss
Stress or anxiety leads to several biochemical changes in the brain. During periods of stress, chemicals like adrenaline and cortisol are released. Adrenaline prepares an individual for “fight or flight response”, typically seen during acute stress/anxiety. Adrenaline promotes the release of cortisol. Both adrenaline and cortisol can adversely affect the memory. The major difference between the two is that cortisol stays in the blood and brain for a longer time than adrenaline. The effect of adrenaline is so powerful that our brain gets fogged out for some time during stress. You could see an individual looking blank and staring into vacuum. Only when the levels of adrenaline drop after stress is reduced does he come back to reality. So, one can imagine that if a person is under chronic stress and thus under the chronic influence of adrenaline and cortisol, it can lead to dysfunction and/or damage to brain. Cortisol is known to cause damage of hippocampus (the seat of memory in brain). An excess of cortisol can impair the hippocampus in such a way that one is unable to form a new memory, and not able to retrieve any existing information too.
            Here, one should remember that not all stress is bad for brain. Small periods of stress (such as stress of getting the project completed within the stipulated deadlines) could have a beneficial effect on brain functions. These brief stressful stimuli could keep the brain in an aroused state for sometime, thereby increasing its efficiency. So, the key is not to completely eliminate the stress but to ensure that it is brief. One should constantly practice means to reduce stress levels such as with practising yoga and meditation.
Effect of stress related memory loss
Chronic stress and subsequent memory loss not only affects the individual who is suffering, but it also impacts the life of immediate circle of relationships. For example, the person is unable to fulfill the roles of a father/mother or husband/wife. The person is irritable, which could further increase on forgetting important things. The person loses interest in sex and other pleasurable activities. This can lead to marital discord, sometimes resulting in divorce/separation. At work too, the person lags behind and is unable to complete tasks on time. Important assignments may be forgotten leading to serious problems for the organization. Affected persons may lose the job.
How can the immediate circle of people help the affected individual?
First of all, it is important to recognize that the person is suffering from stress and stress-related memory loss. Family and friends would be the first ones to notice any deviation from normal in the individual. If a person is found looking lost, or having a worried look all the time or taking longer time to complete simple tasks, one should suspect stress-related memory loss. It may be important to discuss the issue with close family members so that the reasons for stress can be identified. Common stressors include exams/studies, peer pressure, fear of getting reprimanded by the teacher/parents (in children) and interpersonal problems, job-related stress and marital discord (in adults). The affected person should be taken to a psychiatrist/neurologist for evaluation and proper diagnosis.
Differences between memory loss arising from shock and long-term mental trauma
Effects of acute stress or shock on memory differ from that of the long-term stressful events. Acute stress or shock is a sudden onset brief event and the physiological changes are not ongoing, whereas in long-term stress, the physiological changes persist for longer duration. Acute stress can have mixed effects on memory. Some studies report better memory after a brief stress. However, for this to happen, the context for stress and desired memory should be regarding the same topic. Shock also has a specific influence on memory. Most people are not able to recall the events that happened just prior to the shock; however, they are able to remember the place/details regarding the shock itself.
            Long-term stress has more negative influence on memory. Children who are victims of abuse or bullying have difficulty in learning and they perform poorly at school. This effect may persist in their adulthood too. People subjected to chronic stress also find it difficult to adapt to new situations.
Manifestations of stress-induced memory loss in children and adults
The pattern of stress-induced memory loss differs in children from that of adults. In infants and children, the brain is not fully developed and hence any effect of stress can have long-lasting effects. Studies have shown that children who experienced prolonged stress during infancy/early childhood developed memory loss and cognitive difficulties starting in middle age (similar to that occurring in very elderly). In adults, stress mainly affects new learning ability and working memory; however the long-term memory may remain relatively spared.
Is stress-induced memory loss temporary or permanent?
This depends on the type of stress and duration of stress. Typically, after a short-term stress, memory loss is mild and temporary and one can expect a complete improvement. However, after long-term stress, memory can be chronically impaired. This is because, prolonged presence of cortisol (as seen with prolonged stress) can cause severe damage to the hippocampus and prefrontal cortex, brain parts most essential for good memory functions.
Stress in addition to causing diseases like high BP, headaches, and increasing the risks of heart attack and brain stroke, has detrimental effects on memory too. The negative effects on memory of chronic stress are more severe that of acute stress. Memory loss is mediated by the effects of negative effects of prolonged cortisol exposure on hippocampus. Memory loss due to stress can occur at all ages, somewhat more severe in children. Therefore, every attempt should be made to reduce the stress, and prevent it from becoming chronic.

(Note: This article was first published in B Positive magazine, May 2012 issue)

DR SUDHIR KUMAR MD (Medicine), DM (Neurology)
Senior Consultant Neurologist
Apollo Hospitals, Hyderabad
Phone: 0091-40-23607777/60601066
Email: drsudhirkumar@yahoo.com