Assessing Cognitive Disorders

Image: “_MG_0555” by Adrián Martínez. License: CC BY-SA 2.0

Definition of Cognitive Disorders

Cognitive disorders are a group of mental health disorders which predominantly affect learning, memory, perception and problem-solving. They result primarily from primary and secondary abnormalities of the central nervous system.

Four major kinds of cognitive disorders are:

• Delirium: It is characterized by reduced attention/awareness which develops over a short period of time and in a dramatic manner. Toxins and illnesses cause the condition. It is usually reversible.
• Dementia: Unlike delirium, dementia is a chronic and progressive loss of cognitive function, characterized by memory problems, confused thinking, and inability to concentrate. Common causes of dementia include infarction, HIV/AIDS, and Alzheimer’s disease.
• Amnesia: In this condition, a significant loss of memory occurs, but there is no loss of other cognitive functions as seen in dementia.
• Cognitive disorders not otherwise specified: In this kind, cognitive impairment may be due to a general medical condition or substance use.

Tests Performed to Assess Cognitive Function

Mini-mental Status Examination (MMSE)

Advantages

• Short screening structured test to measure cognitive impairment
• Takes approximately 5—10 minutes and covers many cognitive functions
• Easy to establish the score and know the patient’s level of cognitive function.

Disadvantages

• Not helpful for the uneducated as it includes language and mathematical testing
• For mild cognitive impairment, other tests need to be performed
• Questions are verbal; hence it is difficult to measure visuospatial and/or constructional praxis.

The test

The test consists of 11 questions with 5 areas of cognitive function: orientation, registration, attention and calculation, recall, and language can be measured.

Interpreting the Results of Tests Performed to Assess Cognitive Function

MMSE Scoring

24—30: No cognitive impairment

18—23: Mild cognitive impairment

0—17: Severe cognitive impairment

Montreal Cognitive Assessment (MoCA)

It a brief screening test designed to detect cognitive impairment in elders.

Advantages:

• Accessible online and available in several languages
• A good test for an educated person who has only a memory impairment complaint
• A 30-point test which takes about 10 minutes
• Compared to MMSE, this test is more sensitive for the detection of mild cognitive impairment
• Assesses other cognitive domains, such as memory, language, attention, visuospatial and executive functions.

Cognitive domains:

Thirty items assess these multiple cognitive domains:

• Short-term memory recall – 5 points
• Visuospatial abilities evaluated using a clock-drawing task – 3 points and a three-dimensional cube copy task – 1 point
• Executive functioning measured by an adaptation of Trail Making Test – 1 point
• Phonemic fluency – 1 point
• Verbal abstraction – 2 points
• Attention, concentration, and working memory measured using target detection – 1 point
• Serial subtraction – 3 points
• Digits forward – 1 point
• Digits backward – 1 point
• Language measured by confrontation naming of low-familiarity animals – 3 points
• Complex sentences repeated – 2 points
• Orientation to time and place evaluated – 6 points

Interpreting results:

MoCA scoring

Total possible score – 30 points

The score of 26 or above is considered normal

Mini-Cog:

It consists of 2 components:

• 3-words recall test for memory where you score 1 point for each word recalled without cues. Score 0—3.

Scoring: 1 point for each word recalled without cues. Score 0—3.

Simple Decision Tree

“Simple Decision Tree.” by Lecturio.

Clock drawing where you score form 0—2 with :

• 2 points representing normal clock where a normal clock should include all numbers from 1—12 in the correct order and clockwise direction.
• 0 point representing abnormal clock (abnormal hands or missing numbers)..

Advantages of the Mini-Cog:

• Sensitive to measure dementia status
• Short testing time compared to MMSE
• Diagnostic value not limited by the subject’s education or language.

Disadvantages

As a screening test, it does not substitute for a complete diagnostic workup.

Interpreting the Mini-Cog Score:

A mini-cog score can be obtained by adding recall and CDT scores.

• 0—2 points suggest possible impairment.
• 3—5 points suggest no impairment.

Review Questions

The answers can be found below the references.

1. In which kind of cognitive disorder a significant loss of memory occurs, but there is no loss of other cognitive functions as seen in dementia?

1. Amnesia
2. Delirium
3. Cognitive disorder due to a general medical condition
4. Cognitive disorder due to substance use

2. Which of the following test assesses cognitive domains, such as memory, language, attention, visuospatial and executive functions?

1. Montreal Cognitive Assessment (MoCA)
2. Mini-Cog Score
3. Clock drawing task (CDT)
4. Mini-mental Status Examination (MMSE)

3. What are the two components of the Mini-Cog test?

1. 3 words recall test for memory and verbal abstraction
2. 3-words recall test for memory and Clock drawing task (CDT)
3. Complex sentences repeated and orientation to time and place
4. Orientation to time and place and Clock drawing task (CDT)