Mild Cognitive Impairment
Author: David Gigineishvili
Between normal aging and dementia, there is an intermediate condition known as Mild Cognitive Impairment (MCI). Individuals with MCI experience memory problems and other cognitive symptoms that exceed what would be expected for their age. However, these impairments are not severe enough to significantly interfere with daily functioning and therefore do not meet the criteria for dementia. The prevalence of MCI ranges from approximately 16% to 20% and is observed primarily in older adults (Roberts and Knopman, 2013).
Individuals with MCI are at a higher risk of developing Alzheimer’s disease or other forms of dementia compared with those experiencing normal age-related memory changes (Manly JJ et al., 2008). The earlier the condition is recognized and diagnosed, the greater the opportunity to slow disease progression and effectively manage symptoms.
There are numerous factors that contribute to the development of MCI. One of the most important is age, as the condition is more common among older adults. Genetics also plays a significant role; individuals with a family history of memory disorders may have an increased risk of developing MCI. Lifestyle factors likewise have a substantial impact on cognitive health. Physical activity, social engagement, and a healthy diet are all important contributors to maintaining cognitive function. People who lead active social lives and maintain healthy habits may be less likely to develop MCI.
Although subtle and specific changes in cognitive function are often observed as part of normal aging, growing evidence suggests that certain forms of cognitive impairment, including MCI, may represent an early manifestation of a neurodegenerative process that can eventually lead to dementia (Morris JC et al., 2001).
MCI can be classified into several subtypes, including amnestic and non-amnestic forms. Amnestic MCI is primarily associated with memory impairment, in which individuals have difficulty remembering recent events or conversations. In contrast, non-amnestic MCI affects other cognitive domains, such as attention, language, or executive functioning, without significant memory decline. These forms are further categorized as single-domain or multiple-domain MCI, depending on the number of cognitive functions that are affected (Winblad et al., 2004; Hughes et al., 2011; Petersen, 2016). The prognosis of MCI is complex. In a substantial proportion of patients (approximately 50%), the condition progresses over time and eventually develops into dementia. In others, cognitive function may improve, leading to a return to normal cognitive status, or individuals may experience multiple conversions, transitioning between normal cognition, MCI, and dementia over time (Petersen et al., 2014; Lopez OL et al., 2012; Salemme et al., 2025).
Key Characteristics of Mild Cognitive Impairment (MCI)
The individual’s cognitive status is neither normal nor severe enough to meet the diagnostic criteria for dementia (DSM-IV, ICD-10).
There is evidence of cognitive decline compared with the person’s previous level of functioning, demonstrated by one of the following:
The decline is reported by the individual or by a knowledgeable informant and is confirmed through objective cognitive testing; or
A decline in cognitive performance over time is documented through objective cognitive assessments.
Basic activities of daily living remain preserved, including eating, dressing, and personal hygiene. At the same time, more complex instrumental activities of daily living—such as managing medications, handling finances, shopping for groceries and other necessities, and using transportation—are either unaffected or only minimally impaired.
According to the latest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) published by the American Psychiatric Association, cognitive disorders are viewed as part of a single continuum, often referred to as the neurocognitive continuum. Within this framework, the earlier stage is classified as Mild Neurocognitive Disorder (the DSM-5 equivalent of Mild Cognitive Impairment), while the later stage is classified as Major Neurocognitive Disorder (the DSM-5 equivalent of dementia). Notably, the diagnostic criteria for Mild Neurocognitive Disorder largely correspond to those described above for MCI. In addition, DSM-5 provides guidance to clinicians on identifying the underlying etiology and recognizes a range of conditions that may cause either mild or major neurocognitive disorders, including Alzheimer’s disease, frontotemporal degeneration, dementia with Lewy bodies, vascular disease, alcohol-related disorders, and others (APA, 2013).
A broader conceptualization of the spectrum of cognitive impairment and dementia has been proposed by the National Institute on Aging: the preclinical phase of Alzheimer’s disease, in which individuals do not exhibit cognitive symptoms but biomarkers indicate the presence of the pathophysiological processes associated with dementia¹; Mild Cognitive Impairment due to Alzheimer’s disease (the symptomatic pre-dementia phase), in which an individual meets the clinical criteria for MCI while also demonstrating dementia-related biomarkers; and the Alzheimer’s dementia phase, in which the clinical manifestations of dementia are present and supported by biomarker evidence of the disease (Jack CR Jr et al., 2011).
Diagnostic tools play an important role in the identification of MCI. However, there is no single cognitive test that can reliably confirm the diagnosis of MCI. Instead, cognitive assessments may reveal evidence of cognitive decline, thereby providing a basis for further clinical evaluation and diagnostic investigations. Among the available cognitive screening instruments, the Montreal Cognitive Assessment (MoCA) is considered one of the most sensitive tools for detecting MCI, with reported detection rates ranging from 80% to 90% (Nasreddine ZS et al., 2005). When memory impairment is present, specialized tests of episodic memory can be particularly useful in identifying individuals with MCI who are at a higher risk of progressing to dementia (Albert MS et al., 2011).
Studies have shown that many individuals with MCI also experience depression (Ismail et al., 2017). This combination can complicate the diagnostic process because depression may either mimic cognitive impairment or exacerbate existing cognitive deficits, making it difficult to distinguish between MCI and cognitive decline associated with depression. Among the assessment tools that have proven useful for detecting depression in individuals with MCI are the Beck Depression Inventory (BDI), the Zung Self-Rating Depression Scale (SDS), the Cornell Scale for Depression in Dementia, and the depression domain of the Neuropsychiatric Inventory (NPI) (Wong B et al., 2022).
Beyond diagnosis, there is growing interest in how cognitive therapeutic interventions may benefit individuals with MCI. For example, some studies have examined the effectiveness of cognitive training programs designed to help individuals maintain mental sharpness and cognitive performance (Reijnders et al., 2013). These interventions may be beneficial not only for individuals with MCI but also for cognitively healthy older adults, suggesting that relatively simple lifestyle measures—such as engaging in mentally stimulating activities and maintaining social involvement—may help alleviate symptoms and support cognitive health.
Nutrition has also become an important focus of MCI research. However, findings remain inconsistent. Some studies suggest that healthy dietary patterns, particularly adherence to the Mediterranean diet, may be associated with slower progression of MCI and a reduced risk of developing Alzheimer’s disease (Singh et al., 2014; Kheirouri S & Alizadeh M, 2025). Other studies, however, have failed to confirm this association (Sager R et al., 2024). The Mediterranean diet emphasizes whole foods, healthy fats, lean protein sources, and abundant consumption of fruits and vegetables, all of which may contribute positively to brain health.
Understanding these various aspects of MCI enhances our knowledge of the potential mechanisms underlying its development. The complexity of the condition, the diversity of its subtypes, and its interactions with other health conditions further underscore the importance of early diagnosis and timely intervention (Jongsiriyanyong & Limpawattana, 2018). The earlier MCI is identified, the greater the opportunity for individuals to take steps that may improve their quality of life and preserve cognitive health.
¹The pathophysiological process of Alzheimer’s disease refers to the presence of Alzheimer’s disease pathology, specifically the occurrence of at least a moderate density of β-amyloid-containing neuritic plaques within a low-power microscopic field of a neocortical region, together with the regional distribution of neurofibrillary tangle pathology corresponding to Braak and Braak stage IV or higher.
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