Mild cognitive impairment

Refers to some cognitive impairment, that has not progressed to dementia.

Mild cognitive impairment is a heterogeneous condition, defined most recently as a modest decline in cognition, based on clinical and neuropsychological data, that does not significantly impact daily functioning.

Criteria include the concern that there is a change in cognition that the patient or someone close to them notices, that there is objective evidence of cognitive impairment including memory, executive function, attention, language, for visual spatial skills.

There is preservation of independence and functional abilities, although the patient may be less efficient and make errors in performing activities of daily living.

It is defined by performance that is lower than normal on objective neuropsychological cognition test but with maintain daily functions, daily activities at work, home, social settings, and maintain activities of daily living such as personal care and therefore not consistent with dementia.

An intermediate clinical stage between stable normal aging and dementia.

There is no evidence of significant impairment in social or occupational functioning.

Occurs in more than 10% of seniors older than 70 years, and affects more than 20% after the age of 80.

Estimated estimated prevalence of mild cognitive impairment is 7-25% among adults over the age of 60.

Prevalence of 10-20% adults age 65 or older, although the lack of standardized diagnostic criteria is associated with significant uncertainty about these estimates.

Prevalence increases with age and men are at higher risk.

Additional risk factors include low educational level, vascular risk factors of diabetes and hypertension, Apolipoprotein E4 , vitamin D deficiency, sleep disordered breathing, and prior serious illness.

Approximately 19% of individuals 65 years or older and 29% more than 85 years have MCI.

MCI is a risk factor for subsequent development of dementia.

Refers to an intermediate state of cognitive function between the changes of aging and those for dementia and often Alzheimer’s disease (Petersen RC et al).

It does not always progress to dementia, and cognitive status may become normal or fluctuate between MCI, normal cognition, and dementia.

Can be categorized into amnestic MCI, in which reduced performance on memory is the key finding, versus non-amnestic MCI in which there is reduced cognitive performance is in the nonmemory domain such as language.

MCI can also be characterized it to single domain versus multiple domain MCI in which multiple cognitive performance measures are impaired.

Most individuals have a gradual cognitive decline over their lifespan, which does not compromise their ability to function.

Longitudinal studies of patients with MCI show approximately 10-15% of patients per year lose their ability to function reasonably independently, the defining characteristics of dementia.

After 5 years about half of all patients with MCI will meet the criteria for dementia, particularly Alzheimer’s disease and after 10 years most will have Alzheimer’s or another dementia syndrome.

Autopsy studies show 70 to 80% of patients with a diagnosis of MCI prove to have Alzheimer’s disease as the major component of their dementia.

Approximately one in 100 individuals go through life with essentially no cognitive decline.

Refers to a decline in cognitive function beyond that associated with typical aging.

Targeting systolic blood pressure to 120 mm Hg significantly reduces the risk for mild cognitive impairment.

Memory loss with mild cognitive impairment is more prominent and that of normal aging.

Patients typically get important information that they previously would have remembered on the forgetfulness is generally only apparent to individuals close to the patient.

Progressive decline in cognition over months to years.

No evidence of parkinsonism or visual hallucinations which would suggest dementia with Lewy bodies.

Lack of vascular risk factors or extensive cerebrovascular disease on brain imaging.

Lack of prominent behavioral language disorders.

Patients with coronary artery disease and type 2 diabetes have a higher risk.

Neuropsychological testing may be necessary to establish the diagnosis when deficits are subtle.

Neuropsychological testing may distinguish mild cases from normal aging, but is not routinely necessary.

Neuropsychological testing can distinguish from the worried well who can provide a convincing history of memory loss.

Distinguishing from dementia is usually not difficult as the latter have cognitive deficits that affect daily functioning with loss of independence.

Generally progression from MCI to dementia is estimated at 10%-15 per year, compared the general population of 1 to 2% pre-year.

The rate of progression from MCI to dementia is greater among those whose baseline is worse, and the progression is more rapid among carriers of the apolipoprotein (AEPO)e4 allele than among noncarriers.

A community-based study showed that patients with amnestic mild cognitive impairment with volumetric measurements of the hippocampus that fell below 25th percentile for age and sex had a risk of progression to dementia over two years. 2-3 times as high as among persons whose hippocampal measurements were at or above the 75th percentile (Jack CR Jr et al).

Brain aging is accompanied by loss of synaptic connections and attenuated neuropil.

Criteria for diagnosis of mild cognitive impairment include: concern regarding a change in cognition that may be identified by the patient, an informant, or a clinician, impairment in one or more cognitive domains that exceeds the expected level for the patient’s age or educational background, and preservation of independence and functional activities of daily living with some potential mild problems with more complex ones, only minimal assistance needed, and no dementia.

The degree of decline in cognition and function is not consistent with dementia, but there is no exact transition point that defines the progression to the dementia phase.

Up to 15% of patients with mild cognitive impairment will progress to dementia each year.

More than half of patients with mild cognitive impairment will not progress.

Many in whom dementia develops do not meet definitions of mild cognitive impairment before diagnosis, so screening older persons for minor memory changes may be leading to unnecessary investigation and potentially harmful treatment.

May be caused by Alzheimer’s disease, vascular disease, other neurodegenerative diseases and depression.

MCI due to Alzheimer’s disease is characterized by memory impairment, longitudinal decline in cognitive function with a lack of evidence for vascular, traumatic or other medical causes of cognitive decline.

Classified into two subtypes:amnestic and non-amnestic.

Amnestic mild of cognitive impairment is significant memory impairment that does not meet criteria for dementia.

Amnestic mild of cognitive impairment associate with relatively preserved executive function, language function, and visual-spatial skills, and functional activities are basically intact, except for mild inefficiencies.

Nonamnestic mild cognitive impairment is less common than the amnestic and maybe a precursor of dementias such as frontotemporal lobar degenerating or dementia with Lewy bodies (Molano J et al).

Nonamnestic mild cognitive impairment is not related to Alzheimer’s disease.

In patients with amnestic mild cognitive impairment, more than 90% of those progressing to dementia had clinical signs of Alzheimer’s disease (Petersen RC et al).

In a population based study of non demented patients at the time of enrollment, aged 70-89 the prevalence of amnestic MCI was 11.1% and that of nonamnestic MCI was 4.9% (Mayo Clinic Study of Aging).

The risk of developing dementia in the general population is 1-2% per year, while for community based MCI patients they develop dementia at a rate of 5-10%/year and similar patients in specialty clinics (presumably worse) 10-15%er year develop dementia.

Reversion to normal cognition among MCI patients is possible and may be as high as 5-30% (Manly JJ et al).

Exposure of elderly to anesthesia and surgery can transiently affect postoperative cognition, referred to as postoperative cognitive dysfunction.

There is no significant association between cumulative exposure to surgical anesthesia after 40 years of age and mild cognitive impairment.

Mental activity interventions in healthy adults and in individuals with mild cognitive impairment benefit in domain specific improvements, which benefits the specific cognitive activities with little evidence of generalization to other activities or domains.

Exercise interventions in healthy older adults and individuals with mild cognitive impairment with aerobic exercise and resistance training have small to moderate improvements in cognitive function particularly in measures of attention, speed of processing and executive function.

The Mental Activity and eXercise (MAX) trial studied 126 inactive community residing older adults with cognitive impairment and participants engaged in home-based mental activities plus class based physical activities for 12 weeks and were randomized to either mental activity intervention or mental activity control plus exercising intervention or exercise control: There was significant improvement in global cognitive functions with no evidence of difference between intervention and active control groups suggesting that The amount of activity is more important than the type of activities in this population (Barnes DE et al).

Higher HA1c levels associated with lower cognitive function in men with metabolic syndrome with type 2 diabetes and coronary artery disease.

Evaluation of all patients include a comprehensive history and physical examination focusing on cognitive function, medications, functional status, neurological abnormalities, psychiatric abnormalities andlaboratory testing.

Main goals in evaluating MCI are to distinguish from normal aging or dementia to identify potential correctable processes such as depression medication errors, thyroid disease, vitamin B 12 deficiency, and folic acid deficiency.

Annual cognitive assessment for patients aged 65 years or older is encouraged.

Patients older than 65 years who have neurologic illnesses are at even greater risk of cognitive impairment.

There is no evidence for affective pharmacological therapy in MCI.
Large population-based controlled studies found that moderate exercise in mid life or late life is associated with reduced risk of mild cognitive impairment.
Physical exercise may yield positive effects on cognition in MCI, although control trials have yet to determine specific qualities of effective exercise, type, dose, and intensity.
In a three-year trail of older adults, physical activity, cognitive training and physical activity had no effects on cognition relative to placebo.
Mindfulness has had positive effects on mood, quality of life, and cognition among adults with mixed findings among older adults.

Research suggests that mindfulness interventions over weeks to months, May improve specific cognitive abilities in mild cognitive impairment, such as attention, cycle motor function, and aspects of memory.

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