**3. Epidemiology of mild cognitive impairment**

Since MCI imposes a health burden of its own and increases the risk of dementia, it is important to reliably estimate the prevalence of MCI around the globe [25]. However, reported prevalence of MCI significantly differs across studies and ranges between 3 and 54% [5]. It is thought that this difference can be explained by the difference in research methodology, such as employed diagnostic criteria for MCI, variability of used neuropsychological tests, selected cut-off scores (≥1 SD or ≥1.5 SD), subjects of trials - population based or clinic based. Some of the variation may be associated with regional and/or ethnic differences. For example, MCI prevalence in India is 5 times higher than in China, despite standardization for age, sex


uniform diagnostic criteria to more reliably estimate MCI prevalence across different geographical and ethno-cultural regions. They have applied three different diagnostic criteria, such as performance in the bottom 6.681%, Clinical Dementia Rating of 0.5 and Mini-Mental State Examination (MMSE) score of 24–27. Prevalence rates before standardization varied between 5.0 and 36.7%. These estimates were reduced with all definitions ranging between 1.8 and 20.7%. The lowest crude prevalence (5.9%) was obtained with the first definition and highest (12%) with

Mild Cognitive Impairment

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The overall incidence of MCI based on various trials is in range of 21.5 to 71.3 per 1000 person/ year and significantly depends on age. In addition, cardiovascular disease, stroke, Diabetes type 2, Negroid and Hispanic ethnicity are associated with high frequency of MCI. The incidence of aMCI is lower in most of the studies and ranges from 8.5 to 25.9 per 1000 person-

All patients with suspected MCI should undergo detailed physical, neurological, cognitive, psychological and functional status evaluation. It is important to identify potentially reversible causes of MCI, such as depression, thyroid diseases, vitamin B12 and foliate deficiency. Special attention should be given to the prescription history. Some medications, including sedatives, narcotic pain medications, anticonvulsants or anticholinergics have potential to affect cognitive function. An accurate *neurological* assessment is essential to determine poten-

For the accurate diagnosis it is highly important to interview patient's family member or close acquaintance, which is familiar with their functioning in daily activities, requiring planning, organization and communication skills. Ideally, an informant should know the patient for years to adequately recognize deterioration from a baseline of functioning. Information

Clinician should be aware, that cognitive impairment is often accompanied by anxiety, which interferes with cognitive performance; therefore, interview should be held in relaxed and

Examiner should inquire about patient's ability to handle technical devices. For example, patients with MCI can drive cars normally, but they might experience episodes of disorientation when they are driving in an unknown environment, or have a tendency to make wrong turns. Patients with MCI can have particular difficulties while planning a trip or social activities and they might need more time to perform complex activities that require planning and organization [13].

Information should be collected about patient's ability to manage financial operations. Individuals with MCI may require more time to perform monetary transaction, or periodically make careless

Cognitive assessment should be performed at the end of the interview, preferably without an accompanying person. Objective demonstration of cognitive dysfunction is obligatory to

**4. Clinical diagnosis of mild cognitive impairment**

received from different sources should be integrated properly [13].

tial etiology of cognitive impairment [13, 30].

MMSE score of 24–27 [25] (**Table 2**).

years [5, 25, 28, 29] (**Table 3**).

conversational manner.

mistakes.

**Table 2.** Selected epidemiological studies in MCI.


**Table 3.** Selected epidemiological studies in MCI.

and education [25, 26]. According to Einstein aging study, prevalence of MCI in the same geographical zone is higher in Negroid population compared with Caucasians. According to Mayo clinic study of aging, MCI prevalence was 16%, among them 11.1% was amnestic MCI and 4.9% non-amnestic MCI [5]. Single domain amnestic MCI was the most frequent type, based on Mayo clinic study of aging. MCI prevalence is increasing with age, is more frequent in males and *APOE e3e4* or *e4e4* allele carriers. The estimated prevalence of mild cognitive impairment in non-demented cohort of 65 years old or older in the Cardiovascular Health Study was 19% and it increased with age [27].

Recently an international consortium—Cohort Studies of Memory in an International Consortium (COSMIC) harmonized data from 11 studies from USA, Europe, Asia and Australia and applied uniform diagnostic criteria to more reliably estimate MCI prevalence across different geographical and ethno-cultural regions. They have applied three different diagnostic criteria, such as performance in the bottom 6.681%, Clinical Dementia Rating of 0.5 and Mini-Mental State Examination (MMSE) score of 24–27. Prevalence rates before standardization varied between 5.0 and 36.7%. These estimates were reduced with all definitions ranging between 1.8 and 20.7%. The lowest crude prevalence (5.9%) was obtained with the first definition and highest (12%) with MMSE score of 24–27 [25] (**Table 2**).

The overall incidence of MCI based on various trials is in range of 21.5 to 71.3 per 1000 person/ year and significantly depends on age. In addition, cardiovascular disease, stroke, Diabetes type 2, Negroid and Hispanic ethnicity are associated with high frequency of MCI. The incidence of aMCI is lower in most of the studies and ranges from 8.5 to 25.9 per 1000 personyears [5, 25, 28, 29] (**Table 3**).
