mild cognitive impairment

MCI can present with a variety of symptoms, but is divided generally into two types.

Amnestic MCI (aMCI) is mild cognitive impairment with memory loss as the predominant symptom; aMCI is frequently seen as a prodromal stage of Alzheimer's disease.{{cite journal |vauthors= Yu J, Lam CL, Lee TM |title=White matter microstructural abnormalities in amnestic mild cognitive impairment: A meta-analysis of whole-brain and ROI-based studies |journal=Neurosci Biobehav Rev |volume=83 |pages=405–416 |date=December 2017 |pmid=29092777 |doi=10.1016/j.neubiorev.2017.10.026 |type= Meta-analysis and review|doi-access=free }}{{cite journal |vauthors=Petersen RC |title=Mild Cognitive Impairment |journal=Continuum (Minneap Minn) |volume=22 |issue=2 Dementia |pages=404–18 |date=April 2016 |pmid=27042901 |pmc=5390929 |doi=10.1212/CON.0000000000000313 |type = Review}} Studies suggest that these individuals tend to progress to probable Alzheimer's disease at a rate of approximately 10% to 15% per year.{{update after|2020|3|17}}{{cite journal |vauthors=Grundman M, Petersen RC, Ferris SH, etal |title=Mild cognitive impairment can be distinguished from Alzheimer disease and normal aging for clinical trials |journal=Arch. Neurol. |volume=61 |issue=1 |pages=59–66 |year=2004 |pmid=14732621 |doi=10.1001/archneur.61.1.59|s2cid=14831757 |doi-access= }} It is possible that being diagnosed with cognitive decline may serve as an indicator of MCI.{{cite journal | vauthors = Yu H, Wang K, Zhong P, Cheng HD, Lv XY, Yuan LL | title = Investigations of Memory Monitoring in Individuals With Subjective Cognitive Decline and Amnestic Mild Cognitive Impairment | journal = Cogn Behav Neurol | volume = 33 | issue = 3 | pages = 201–207 | date = September 2020 | pmid = 32889952 | doi = 10.1097/WNN.0000000000000242 | s2cid = 221511593 }}

Nonamnestic MCI (naMCI) is mild cognitive impairment in which impairments in domains other than memory (for example, language, visuospatial, executive) are more prominent.{{Cite journal|vauthors= Petersen RC |date=September 2004|title=Mild cognitive impairment as a diagnostic entity|journal=Journal of Internal Medicine|volume=256|issue=3|pages=183–194|doi=10.1111/j.1365-2796.2004.01388.x|pmid=15324362|s2cid=6618420|issn=0954-6820|doi-access=free}} It may be further divided as nonamnestic single- or multiple-domain MCI, and these individuals are believed to be more likely to convert to other dementias (for example, dementia with Lewy bodies).{{cite journal |vauthors=Tabert MH, Manly JJ, Liu X, etal |title=Neuropsychological prediction of conversion to Alzheimer disease in patients with mild cognitive impairment |journal=Arch. Gen. Psychiatry |volume=63 |issue=8 |pages=916–24 |year=2006 |pmid=16894068 |doi=10.1001/archpsyc.63.8.916|doi-access=free }}

Mild cognitive impairment (MCI) may be caused due to alteration in the brain triggered during early stages of Alzheimer's disease, to other causes, or to a combination of causes.{{cite web | title = Mild cognitive impairment (MCI) | publisher = Mayo Clinic | url = https://www.mayoclinic.org/diseases-conditions/mild-cognitive-impairment/symptoms-causes/syc-20354578 | access-date = 30 Sep 2020}}{{Cite journal |last1=Petersen |first1=R. C. |last2=Caracciolo |first2=B. |last3=Brayne |first3=C. |last4=Gauthier |first4=S. |last5=Jelic |first5=V. |last6=Fratiglioni |first6=L. |date=March 2014 |title=Mild cognitive impairment: a concept in evolution |journal=Journal of Internal Medicine |language=en |volume=275 |issue=3 |pages=214–228 |doi=10.1111/joim.12190 |issn=0954-6820 |pmc=3967548 |pmid=24605806}} Brain damage, brain injury, delirium and prolonged substance abuse can cause MCI. HIV-associated neurocognitive disorder can cause MCI. Risk factors of both dementia and MCI are the same, and include: aging, genetics, and cardiovascular disease.{{cite news |url=http://www.alz.org/dementia/mild-cognitive-impairment-mci.asp |title=Mild Cognitive Impairment |work=Alzheimer's Association|access-date=July 9, 2017}}

The diagnosis of MCI requires clinical judgement, possibly including clinical observation, neuroimaging,{{cite journal |vauthors=Smailagic N, Vacante M, Hyde C, Martin S, Ukoumunne O, Sachpekidis C |title=¹⁸F-FDG PET for the early diagnosis of Alzheimer's disease dementia and other dementias in people with mild cognitive impairment (MCI) |journal=Cochrane Database Syst Rev |volume=1 |pages=CD010632 |date=January 2015 |issue=1 |pmid=25629415 |doi=10.1002/14651858.CD010632.pub2 |pmc=7081123 }} blood tests and neuropsychological testing. MCI may be diagnosed differently by different clinicians using different definitions or criteria, but generally including:{{cite journal |vauthors=Morris JC, Storandt M, Miller JP, McKeel DW, Price JL, Rubin EH, Berg L |title=Mild cognitive impairment represents early-stage Alzheimer disease |journal=Arch. Neurol. |volume=58 |issue=3 |pages=397–405 |date=March 2001 |pmid=11255443 |doi=10.1001/archneur.58.3.397 |doi-access= }}

1. Evidence of modest cognitive decline from a previous level of performance in one or more cognitive domains, based on either: concern about cognitive decline from the individual, a knowledgeable informant, or a clinician, or modest impairment in cognitive performance documented by standardized neuropsychological testing.
2. The cognitive deficits do not interfere with capacity for independence in everyday activities. However, greater effort, compensatory strategies, or accommodation may be required for complex tasks.

Magnetic resonance imaging can observe deterioration, including progressive loss of gray matter in the brain, from MCI to full-blown Alzheimer dementia.{{cite journal |vauthors=Whitwell JL, Shiung MM, Przybelski SA, etal |title=MRI patterns of atrophy associated with progression to AD in amnestic mild cognitive impairment |journal=Neurology |volume=70 |issue=7 |pages=512–20 |year=2008 |pmid=17898323 |doi=10.1212/01.wnl.0000280575.77437.a2 |pmc=2734138}} A technique known as PiB PET imaging is used to show the sites and shapes of beta amyloid deposits in living subjects using a ¹¹C tracer that binds selectively to such deposits.{{cite journal |vauthors=Jack CR, Lowe VJ, Senjem ML, etal |title=11C PiB and structural MRI provide complementary information in imaging of Alzheimer's disease and amnestic mild cognitive impairment |journal=Brain |volume=131 |issue=Pt 3 |pages=665–80 |year=2008 |pmid=18263627 |doi=10.1093/brain/awm336| url= |pmc=2730157 }} Individuals with MCI may have increased oxidative damage in their nuclear and mitochondrial brain DNA.{{cite journal |vauthors=Wang J, Markesbery WR, Lovell MA |date=February 2006 |title=Increased oxidative damage in nuclear and mitochondrial DNA in mild cognitive impairment |journal=J. Neurochem. |volume=96 |issue=3 |pages=825–32 |doi=10.1111/j.1471-4159.2005.03615.x |pmid=16405502 |s2cid=23689125 |doi-access=}}

{{See also|Neurobiological effects of physical exercise}}

The American Academy of Neurology's (AAN) clinical practice guideline on MCI from January 2018 stated that clinicians should identify modifiable risk factors in individuals with MCI, assess functional impairments, provide treatment for any behavioral or neuropsychiatric symptoms, and monitor the individual's cognitive status over time. It also stated that medications which cause cognitive impairment should be discontinued or avoided if possible. Due to the lack of evidence supporting the efficacy of cholinesterase inhibitors in individuals with MCI, the AAN guideline stated that clinicians who choose to prescribe them for the treatment of MCI must inform patients about the lack of evidence supporting this therapy. The guideline also indicated that clinicians should recommend that individuals with MCI engage in regular physical exercise for cognitive symptomatic benefits; clinicians may also recommend cognitive training, which appears to provide some symptomatic benefit in certain cognitive measures. Current evidence suggests that cognition-based interventions do improve mental performance (i.e. memory, executive function, attention, and speed) in older adults and people with mild cognitive impairment.{{cite journal |vauthors=Martin M, Clare L, Altgassen AM, Cameron MH, Zehnder F |date=January 2011 |title=Cognition-based interventions for healthy older people and people with mild cognitive impairment |journal=The Cochrane Database of Systematic Reviews |issue=1 |pages=CD006220 |doi=10.1002/14651858.cd006220.pub2 |pmid=21249675}} Especially, immediate and delayed verbal recall resulted in higher performance gains from memory training.

Diet improvements are likely beneficial to MCI. However, there is currently limited evidence to form a strong conclusion to recommend particular carbohydrate supplements in preventing or reducing cognitive decline in older adults with normal cognition or mild cognitive impairment.{{cite journal |vauthors=Ooi CP, Loke SC, Yassin Z, Hamid TA |date=April 2011 |title=Carbohydrates for improving the cognitive performance of independent-living older adults with normal cognition or mild cognitive impairment |journal=The Cochrane Database of Systematic Reviews |volume=2011 |issue=4 |pages=CD007220 |doi=10.1002/14651858.cd007220.pub2 |pmc=7388979 |pmid=21491398}}

According to research conducted in England, people with MCI often do not receive adequate care and support in healthcare settings. This leaves them and their families in a limbo with uncertainty regarding their futures and the fear of possibly developing dementia. The lack of services also fails to point them to effective ways to prevent dementia such as exercise and social contact. Successful dementia prevention services would have to be tailored to people's preferences and backgrounds.{{Cite journal |last=Saul |first=Helen |date=2020-10-23 |title=People with mild memory problems are left in limbo between health and dementia, and need help to make lifestyle changes |url=https://evidence.nihr.ac.uk/alert/people-with-mild-memory-problems-are-left-in-limbo-between-health-and-dementia-and-need-help-to-make-lifestyle-changes/ |access-date=2022-12-05 |website=NIHR Evidence |publisher=National Institute for Health and Care Research |language=en-GB |type=Plain English summary |doi=10.3310/alert_42131|s2cid=241882442 |url-access=subscription }}{{Cite journal |last1=Poppe |first1=Michaela |last2=Mansour |first2=Hassan |last3=Rapaport |first3=Penny |last4=Palomo |first4=Marina |last5=Burton |first5=Alexandra |last6=Morgan-Trimmer |first6=Sarah |last7=Carter |first7=Christine |last8=Roche |first8=Moïse |last9=Higgs |first9=Paul |last10=Walker |first10=Zuzana |last11=Aguirre |first11=Elisa |last12=Bass |first12=Nicholas |last13=Huntley |first13=Jonathan |last14=Wenborn |first14=Jennifer |last15=Cooper |first15=Claudia |date=1 July 2020 |title=" Falling through the cracks "; Stakeholders' views around the concept and diagnosis of mild cognitive impairment and their understanding of dementia prevention |journal=International Journal of Geriatric Psychiatry |language=en |volume=35 |issue=11 |pages=1349–1357 |doi=10.1002/gps.5373 |pmid=32608171 |s2cid=220288902 |issn=0885-6230|doi-access=free |hdl=10871/123313 |hdl-access=free }}

As MCI may represent a prodromal state to clinical Alzheimer's dementia, treatments for Alzheimer's disease could potentially be useful.{{Cite journal |last1=Feng |first1=Lei |last2=Cheah |first2=Irwin Kee-Mun |last3=Ng |first3=Maisie Mei-Xi |last4=Li |first4=Jialiang |last5=Chan |first5=Sue Mei |last6=Lim |first6=Su Lin |last7=Mahendran |first7=Rathi |last8=Kua |first8=Ee-Heok |author-link8=Kua Ee Heok |last9=Halliwell |first9=Barry |date=2019-03-12 |editor-last=Yu |editor-first=Jin-Tai |title=The Association between Mushroom Consumption and Mild Cognitive Impairment: A Community-Based Cross-Sectional Study in Singapore |url=https://www.medra.org/servlet/aliasResolver?alias=iospress&doi=10.3233/JAD-180959 |journal=Journal of Alzheimer's Disease |volume=68 |issue=1 |pages=197–203 |doi=10.3233/JAD-180959 |pmid=30775990 |s2cid=73512492|url-access=subscription }} Of these, rivastigmine failed to stop or slow progression to Alzheimer's disease or to improve cognitive function for individuals with mild cognitive impairment;{{cite journal |vauthors=Feldman HH, Ferris S, Winblad B, etal |title=Effect of rivastigmine on delay to diagnosis of Alzheimer's disease from mild cognitive impairment: the InDDEx study |journal=Lancet Neurol |volume=6 |issue=6 |pages=501–12 |year=2007 |pmid=17509485 |doi=10.1016/S1474-4422(07)70109-6|s2cid=10742472 }} donepezil showed only minor, short-term benefits and was associated with significant side effects.{{cite journal | vauthors = Birks JS, Harvey RJ | title = Donepezil for dementia due to Alzheimer's disease | journal = Cochrane Database Syst Rev | volume = 2018 | issue = 6| pages = CD001190 | date = June 2018 | pmid = 29923184 | pmc = 6513124 | doi = 10.1002/14651858.CD001190.pub3 }}

MCI does not usually interfere with daily life.

The prevalence of MCI varies by age. The prevalence of MCI among different age groups is as follows: 6.7% for ages 60–64; 8.4% for ages 65–69, 10.1% for ages 70–74, 14.8% for ages 75–79, and 25.2% for ages 80–84. After a two-year follow-up, the cumulative incidence of dementia among individuals who are over 65 years old and were diagnosed with MCI was found to be 14.9%.

Due to the emphasis shifting to the earlier diagnosis of dementia, more people are assessed who report memory problems. In turn this also leads diagnosing more people who might have MCI which is a risk factor for dementia. Globally, approximately 16% of the population over the age of 70 experiences some type of MCI.{{medcn|date=March 2020}}

MCI was initially conceptualized as an intermediate stage between normal aging and Alzheimer's disease.{{Cite journal |last=Petersen |first=R. C. |date=September 2004 |title=Mild cognitive impairment as a diagnostic entity |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1365-2796.2004.01388.x |journal=Journal of Internal Medicine |language=en |volume=256 |issue=3 |pages=183–194 |doi=10.1111/j.1365-2796.2004.01388.x |pmid=15324362 |issn=0954-6820}} In 2003 international criteria for MCI were developed that broadened the definition to include people with cognitive impairment due to any etiology.{{Cite journal |last1=Petersen |first1=R. C. |last2=Caracciolo |first2=B. |last3=Brayne |first3=C. |last4=Gauthier |first4=S. |last5=Jelic |first5=V. |last6=Fratiglioni |first6=L. |date=March 2014 |title=Mild cognitive impairment: a concept in evolution |url=https://onlinelibrary.wiley.com/doi/10.1111/joim.12190 |journal=Journal of Internal Medicine |language=en |volume=275 |issue=3 |pages=214–228 |doi=10.1111/joim.12190 |issn=0954-6820|pmc=3967548 }} Furthermore, the definition of Alzheimer's disease expanded to include earlier, non-dementia, stages. So now, MCI can either be a diagnosis associated with early Alzheimer's disease (i.e., people with MCI that also have Alzheimer's disease) or a diagnosis of cognitive decline due to a cause other than Alzheimer's disease; it is no longer considered to be a stage between normal aging and Alzheimer's disease.{{Cite web |date=2024 |title=Alzheimer's Disease Facts and Figures 2024 |url=https://www.alz.org/media/Documents/alzheimers-facts-and-figures.pdf |website=Alzheimer's Association}}

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{{Medical resources

| DiseasesDB =

| ICD10 = {{ICD10|F|06|7|f|00}}

| ICD9 = {{ICD9|331.83}}

| ICDO =

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| MeshID = D060825

| SNOMED CT = 386805003

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{{Mental and behavioral disorders|selected = neurological}}

{{CNS diseases of the nervous system}}

Category:Alzheimer's disease

Category:Cognitive disorders

Category:Learning disabilities

Category:Neurocognitive disorders