**2. Cognition and its evaluation**

#### **2.1. Cognition**

Higher brain function may be subclassified into: (a) distributed functions, which do not localize to a particular brain region but instead require the concerted action of multiple parts on both sides of the brain, for example, attention and concentration, memory, higher-order executive function, social conduct, and personality; (b) localized functions, which are dependent on the normal structure and function of a particular part of one cerebral hemisphere, for example, language and praxis in dominant hemisphere the nondominant hemisphere hemisphere is largely, though not exclusively, responsible for visuospatial skills [18]. Cognitive impair‐

ment without crossing the threshold for dementia has been termed "mild cognitive impair‐ ment" (MCI) [19]. The MCI syndrome, as an expression of an incipient neurodegenerative disorder that may lead to dementia, is extremely heterogeneous and may coexist with systemic, neurologic, or psychiatric disorders that can cause cognitive deficits [20]. The criteria for MCI encompassed all possible cognitive manifestations of the syndrome and four subgroups have been proposed: deficits only in memory functions; memory deficits plus deficits in another cognitive domain; deficits in a single nonmemory domain; and deficits in more than one nonmemory domain [21].

#### **2.2. Evaluation of cognitive functions**

#### *2.2.1. The Montreal cognitive assessment (MoCA)*

MOCA was used as test of cognition, measure cognitive function, its cognitive domains: visuospatial/ executive function; naming; memory; language; abstraction; and attention. MoCA is scored out of 30 points. A normal score is 26 or above [22].

#### *2.2.2. Mini Mental State Examination (MMSE)*

MMSE is used for global cognitive functioning measurement [23].

*2.2.3. Other cognitive domain-specific areas neuropsychological tests: focus on domain-specific areas of cognition:*

(1) Hayling Sentence Completion Test, Word Span and Corsi's Test to test working memory [24], verbal and visual memory—Recognition Memory Tests, Words, and Topography [25]. (2) Rey Auditory Verbal Learning Test—RAVLT and logical memory to assess episodic memory, immediate and delayed recall [26], abstract reasoning: nonverbal—Raven's ad‐ vanced progressive matrices [27, 28], verbal—Proverb Interpretation Test [29]. (3) Attention— Digit Span sub-test from the Wechsler Adult Intelligence Scale-III [30], Elevator Counting with Distraction from the Test of Everyday Attention [31], Trail Making test, part A and part B to test simple speed processing and complex attention, respectively, [32]. (4) Visual perception —Incomplete Letters Test from the Visual Object and Space Perception Battery [33], Rey– Osterrieth Complex Figure recall, to test visuospatial long-term memory, Rey–Osterrieth Complex Figure, copy to test visuoconstructional abilities [34]. (5) Phonemic and semantic fluency [35], language—Graded Naming Test [36], Word Comprehension—Synonyms Test [37]. (6) Executive functions—phonemic word fluency [38]. (7) Frontal Assessment Battery— FAB to assess frontal functionality [39].

For neuropsychological measures, age-, gender-, and education-corrected scores and equiva‐ lent scores should be calculated from the raw scores according to normative standards.
