Cognitive function assessment in MSE
COGNITIVE FUNCTION TESTS:
The purpose of cognitive function test is to confirm the presence or absence of one of the two forms of global cognitive impairment, delirium (the acute confusional state) or dementia. Cognitive screening should routinely be carried out in middle aged and elderly patients, and in patients of any age in whom there is diagnostic uncertainty or physical illness that can affect brain function. This can be complemented by carrying out the Mini Mental State Examination (Folstein et al 1975), which can be a useful measure of the severity of cognitive impairment.
Consciousness is essentially first step towards evaluating higher mental functions. In acute stages of illness, patient’s sensorium may be varying depending on the etio-pathogenesis. From a neurological perspective consciousness is evaluated objectively using Glasgow Coma Scale (GCS) which assess the level of sensorium based on verbal, motor and eye opening response.
Patients can be in varying stages of sensorium which includes awake, drowsy, stupor and coma. When the patient is awake and fully aware of normal internal and external stimuli, then the sensorium is said to be in alert state. When patients needs to be constantly stimulated to keep awake, otherwise drifts in to sleep is when the patient is in drowsy state. Most sedative medications will result in this state. When the patient needs vigorous stimulation to open eyes or move his limbs or respond verbally, then the patient is in stupor or semi coma. If there is minimal response to painful stimulus with the eyes closed, then the patient is said to be in comatose state of sensorium. If the patient presents with comatose or stupor, then detailed neurological and systemic examination needs to be done to evaluate the cause of altered state of consciousness.
If the patient is conscious then patient’s orientation to time, place and person needs to be checked. Normally patients are said to be ‘oriented times three’ if they know who they are, their location and the current time and date. Orientation to time is sensitive indicator impairment in attention of the patient. Time disorientation of more than+/- 2 hours is significant. Orientation to self/ family and place will be impaired in patients with delirium. If there is an impartment in orientation, attention and concentration needs detailed evaluation.
Attention and Concentration:
Attention is the ability of the individual to attend to a specific stimuli without distracted by internal and external stimuli. Attention is the basic higher mental function which enables individuals to attend and orient themselves to the self and environment. It is also necessary for retention of new information and recall of the previous experiences, which is called memory. Sustained attention to a specific stimulus over an extended period is called as concentration. Subsequent tests and mental status examination will depend of adequate attention and concentration as it affects the person’s ability to comprehend questions, recollect information and respond appropriately to subsequent tests.
The following are the routine clinical tests for evaluating attention and concentration.
- Digit Span Test: It is the standardized bed side test to evaluate the attention span of individuals. It includes digit forward and digit backward. The patient is asked to repeat the random numbers told by the examiner followed by asking the patient to repeat the numbers in reverse order. The numbers should be given slowly, which is one number per second and the numbers should not have any serial numbers like even or odd numbers. Patient is asked to repeat till he completes the task correctly. Normal range of digit forward is 7 +/- 2 (5 to 9) and digit backwards is 5 +/-2 (3 to 7).
Examples of random numbers for digit span test
- Serial Subtraction: Serial subtraction assess the patient’s attention, working memory and calculation abilities. Standardized serial subtraction includes to perform 20 minus 1 in 20 seconds, 40 minus 3 in 1 minute and 100 minus 7 in 2 minutes. More than 2 mistakes is taken as abnormal based on the individual’s educations background. In case the person is illiterate then attention test includes asking the patient to tell days in reverse order.
- A – Random letter test: it consists of a series of random letters among which a target letter appears with greater than random frequency. The patient is required to indicate whenever the target letter is spoken by the examiner.
Language is the mechanism for expressing thoughts and ideas as follows: by speech (auditory symbols), by writing (graphic symbols) or by gestures and pantomime (motor symbols). Speech consists of words, which articulate vocal sounds that symbolize and communicate ideas. Articulation is the enunciation of works and phrases; it is a function of the organs and muscles innervated by the brain stem. Aphasia is the disorder of language and dysarthria is a disorder of motor production or articulation of speech. Language assessment is the essential prerequisite for mental status examination.
Detailed language assessment is required if there is suspicion of any kind of aphasias. Language can be evaluated under the following aspects
Speech output: Spontaneous speech if present needs to observed, followed by responses to questions. Normal speech fluency is around 100 – 115 words per minute. Fluency is affected by many neurological and psychiatric conditions. Speech output less than 10 – 15 words per minute is said to be low or reduced.
Comprehension: Comprehension is the ability of the patient to understand speech. It can be tested by assessing the responses to the requests or command. Comprehension is tested by having the patient follow verbal commands like ‘show me your teeth’, ‘point to the fan’. Comprehension is judged to be reasonably intact if the patient follows a complicated, multistep command.
Naming and Repetition: Evaluation of naming and repetition is essential when the patient has aphasia secondary to a lesion the brain. Repetition of words or sentences is impaired in lesions involving the arcuate fasciculus and is called as conduction aphasia.
Reading and writing: Evaluation of reading and writing will complete the language assessment, which has to be done in patients with aphasia. Reading and writing is important task in children with learning disorders.
- Comprehension and attention should be evaluated in all patients with irrelevant speech
The important mechanisms by which the environment alters behaviour are learning and memory. Memory and learning are necessary for adapting to any new situations. Based on the time of recollection memory is classified in to
- Short term memory
- Recent memory
- Long term memory
Short term memory:
Short term memory can be classified as immediate memory and working memory. Immediate memory is the ability to register and recollect immediately, Ex; recollecting the numbers immediately in digit forward test. All attention tests evaluate immediate memory and if there is impairment in attention tests it results in impairment in registration and immediate recall of the information. Working memory also called as primary memory is the purposeful use of immediate memory Ex; using of phone numbers when dialing. Working memory has two components the first is short-term or immediate memory which lasts for several seconds and the second component is the executive function which is the organization of the immediate information. Ex: using numbers while dialing telephone number, which included remembering the numbers and using in a particular order. Tests which elicits this function are digit backward test, serial subtraction.
Recent memory: It is the ability to recollect information after minutes to days. Recent memory refers to knowledge accumulated in the last few days or weeks. Recent memory can be tested objectively 24 hours recall test and object recall test.
3 object test is routinely used bed side clinical test to evaluate the recent memory function in the patients. In 3 objects patients are given 3 objects which are unrelated and from various categories.
- Objects given should not be present in the immediate environment and the objects should not be related to each other.
- Each object should be registered before the recall test is performed, by repeating to the patients if required.
- The objects are then asked after 5 minutes, 10 minutes and 30 minutes.
- After the asking the patient to repeat the objects, he is given different tasks to distract him from repeated recollection or rehearsing of the objects.
- Normally individuates should be able to recollect all the objects after 5 minutes and subsequent time.
- Examples include orange, umbrella and honesty.
The Address Test similar to 3 object recall test, except the address consisting of 4 – 5 components are given to the patient to be remembered and recalled. Example # 215, 9th Cross, 2 Main, Vijay Nagar, Bangalore, the above example includes five different components needed to be remembered and recalled after 5 minutes.
Visual memory (hidden memory) is evaluated by showing the patients 3- 5 objects and are kept hidden in front of him. Following this he is asked repeat the items and the place when it has been kept. Then he is distracted by asking different questions. After 5 minutes he is asked to name the objects and where have they been hidden. Impairment is usually seen in the non-dominant temporal lobe involvement.
24 hour recall by asking the patient to recollect the 24 hours of his day and it needs corroboration by the family members. The person’s orientation to person, place and time also evaluated the patient’s new learning recent memory. Other tests include paired associate learning tests to assess the recent memory.
Remote memory: Remote memory refers to knowledge accumulated over several years. It is reasonably robust and lasts for decades. Remote memory is elicited by asking questions about the personal information or facts
- Personal information like Birth date, personal life events like date of marriage or childbirth, information about schooling and work are examples of episodic remote memory.
- Semantic memory is ability of the individual to remember facts. Examples for the same include year of independence or events of national importance.
Intellectual functioning of the patient is essential for understanding patient’s psychopathology and illness. Adequate intellectual functioning has a bearing on the management and outcome of patients. Developmental history and current level of intellectual functioning should be thoroughly elicited and during MSE the same needs to be validated. Also a decision for formal assessment of intellectual functioning should be considered if there is any areas of deficits or clinical suspicion. Important aspects of intellectual functioning includes General fund of information, Comprehension, Arithmetic, Abstract thinking.
General fund of information: the questions asked in this test provide a reasonable estimate fo the patients store of knowledge or fund of general information. They are presented in the order of increasing difficulty, it is continued till the test is completed or until the patient has failed three successive questions.
- How many weeks in a year? – 52
- Name 4 prime minister of our country? Indira Gandhi, Rajiv Gandhi, Pandit Nehru, Narendra Modi
- Why do people have lunges? – to transfer oxygen
- How far is Delhi from Bangalore? 2000 – 3000Kms
- Who wrote Ramayana? Valmiki
- Why do we wear light colored clothes in summer? Light colour clothes reflect heat and keeps us cool
- What causes rust? Oxidation – a chemical reaction of metal with water and oxygen
Comprehension is usually evaluated while assessing the language in detail. Impairment in comprehension for complex tasks or multistep tasks should be evaluated.
Calculations are complex functions and important components of calculations include mathematical skills like addition, subtraction and multiplication
- basic concept of carrying and borrowing
- recognition on signs (ex : +, -)
- Correct special alignment for written calculations
Verbal Rote examples:
- Addition: 4 + 6 = (10), 7 + 9 = (16)
- Subtraction: 8 – 5 = (3), 17 – 9 = (8)
- Multiplication: 2 * 8 = (16), 9 * 7 = (63)
- Division: 9 / 3 = (3), 56 / 8 = (7)
To evaluate the complex calculation abilities both verbal and written examples can be given.
Abstract thinking is higher order thinking which is present in an adult with normal intelligence which primarily evaluated deductive thinking. Patients with schizophrenia can have concrete responses.
Orange and Banana: abstract response – both fruits, Concrete response – one is round and other is long
Car and Airplane: Abstract response – modes of transport, concrete response – one’s in the air and one’s on the road
Other examples include Lion and Tiger, Ear and Eyes, North and South.
Proverb interpretation requires an intact fund of general information, the ability to apply this knowledge in unfamiliar situations and the ability to think in abstract.
Ask for any provers patient is aware and ask for the abstract meaning for the same. If the patient is not aware, then give an example and mention the abstract meaning in it. Followed by common proverbs in the local language can be asked with their abstract or conceptual meaning.
Don’t cry over spilt milk:
- Concrete response – the milks all over the floor or when the milk is on the floor you can’t use it
- Abstract response – once something is over, don’t worry about it
– Dr Girish Babu N