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Mild cognitive impairment [MCI] or Minor Neurocognitive Disorder is the intermediate state between normal ageing and the more serious condition of dementia or Major Neurocognitive Disorder. Patients with MCI have memory and other cognitive impairments beyond that expected for their age and are at increased risk of developing dementia later.
Even though MCI occurs primarily in people older than age 60, it is never a part of normal aging. As people age, they may experience some decline in memory - for example they may become slower in learning new things and have slight difficulty in recalling previously learnt information. MCI however causes greater declines in cognitive ability which can be easily measured.
Mild cognitive impairment is often but not always the pre-dementia state. In MCI, affected individuals have memory and other cognitive impairments but function normally to a great extent whereas in dementia the cognitive deficits are sufficiently severe to interfere with the day to day functioning of affected individuals.
It is estimated that 15 - 20 per cent of the population over the age of 65 years may be experiencing MCI. As a rule of thumb, for every person with dementia in the community there are two or three persons with MCI.
Just as in dementia, recent memory loss is the most common symptom of MCI. Other cognitive symptoms like speech/language difficulties, way finding difficulties and difficulties with complex multistep activities/decision making can also occur. Symptoms of depression or anxiety also occur in a substantial proportion of people with MCI.
There are many different causes for MCI. Some people will be in the early stages of Alzheimer's disease. Others will have MCI as a result of Stroke, Parkinson’s disease, Frontotemporal Dementia, Normal Pressure Hydrocephalus, depression or certain medications. Any condition that causes dementia can also cause MCI.
MCI is diagnosed by asking the primary caregiver certain questions. Then the person with suspected MCI is given a memory test. Doctors also look for clues suggesting depression or neurological disease [Stroke, Parkinson’s disease or Normal Pressure Hydrocephalus] as a possible cause.
Blood tests are done to rule out thyroid or vitamin deficiency. A brain scan [CT or MRI] is performed to rule out a stroke or normal-pressure hydrocephalus. More detailed memory testing (called neuropsychological testing) is more often needed to clarify the presence and degree of cognitive impairment in MCI than in suspected dementia, especially in subjects with a high education level.
A number of treatments have been/are currently being investigated to see whether they can prevent or delay dementia in people with MCI. These include vitamins, antioxidants, cholesterol lowering drugs, drugs approved for Alzheimer’s disease such as Donepezil, Rivastigmine and Galantamine and herbal medicines like Gingko biloba, Gotu Kola/Vallarai or Lunuwila/Brahmi. At the moment there is not enough evidence to routinely recommend any specific treatment.
Approximately about 10 - 15 per cent of persons with MCI go on to develop dementia every year compared to about 1 – 3 % of normal community dwelling elderly persons every year. However, many people with MCI also improve or remain stable.
Various methods have been used to identify patients with MCI who will go on to develop dementia later. These include genetic testing for the ApoE4 epsilon gene, MRI brain scans, FDG PET/Amyloid PET scanning of the brain and measuring the levels of proteins like tau and Amyloid-beta 42 in the cerebrospinal fluid [CSF]. More research however needs to be done before these can be adopted in routine clinical practice.
Almost 40 -50% of the risk of developing cognitive decline [MCI or dementia] can be mitigated by the following measures:
