The Memory Disorders

The Memory Disorders

Mild Cognitive Impairment (MCI)

(called Mild Neurocognitive Disorder in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition)

MCI is a syndrome of cognitive decline greater than expected for an individual’s age and education level, but it does not meet the diagnostic criteria for dementia. The cognitive changes (deficits) in memory, language, visuospatial ability, or executive function are severe enough to be noticeable to other people and to show up on tests of cognitive functioning. However, these changes are not severe enough to significantly interfere with the person’s everyday social and occupational functioning. This is what distinguishes this cognitive disorder from dementia. MCI is currently receiving a great deal of clinical and research attention. One important goal of this research is to identify and treat individuals before they develop dementia and if possible delay or prevent progression to dementia. Mild Cognitive Impairment increases a person’s risk of later developing dementia, including Alzheimer’s disease, especially when the main difficulty is with memory. In many cases, MCI is actually the prodromal stage of dementia and the transitional phase between normal age-related cognitive decline and early dementia. However, some people with mild cognitive impairment do not go on to develop dementia. MCI is not a normal part of aging.


(called Major Neurocognitive Disorder in the DSM-5)

Dementia is a general term for a group of brain disorders. In medical terms it is a syndrome meaning it is a collection of signs and symptoms that tend to occur together. It is an umbrella term used to describe any significant and persistent decline in cognitive function.

Dementia is a neurological disorder characterized by the loss of cognitive abilities including memory, language skills, reasoning ability, abstract thinking, spatial ability and orientation along with personality and behavioral changes.  Dementia is caused by brain damage resulting from an event such as a traumatic brain injury or a stroke or from a progressive disease such as Alzheimer’s disease. The parts of the brain that are most affected are the association areas of the brain, which integrate sensory information, thought, memory, and purposeful behavior. When extensive damage to these areas occurs, the affected person will begin showing cognitive deficits, mild at first and gradually becoming more severe.

Most dementias begin gradually (months to years) as with Alzheimer’s disease, but may begin suddenly, as after a major stroke or traumatic brain injury.  The symptoms of dementia may be reversible as when the cause is a medication side effect or a correctible medical condition such as a thyroid disorder. Other potentially reversible causes include infections, toxins, nutritional deficiencies, metabolic disturbances, and even psychiatric conditions such as major depression.  However, most types of dementia are non-reversible and progressive such as with Alzheimer’s disease. It is worth noting that dementia is not the same as Alzheimer’s disease because a person can have dementia and not have Alzheimer’s disease as the cause. A person can have dementia due to vascular disease, for example. However, if a person has been diagnosed with Alzheimer’s disease by a primary care physician or a neurologist, this means the patient has dementia, most likely due to Alzheimer’s disease. In this case all other possible causes have been ruled out if a thorough dementia evaluation has been conducted.  


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2nd Edition Oxford University Press, New York, N.Y. 2015

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