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Detecting Cognitive Deficits in Schizophrenia

The cognitive deficits that can occur in Schizophrenia tend to have a significant impact on the level of disability that a person with this condition will endure [ref], and it is thus important that these areas of functioning be assessed when treating individuals with Schizophrenia. For a thorough and exhaustive examination of a person's cognitive deficits, an evaluation by a neuropsychologist is usually required.  However, there are many simple techniques that a clinician can perform in their own practice to assess whether a patient has any cognitive deficits:

  1. Testing attention, vigilance and working memory:  These functions are all tested together using the same techniques as they are very closely related and do not operate independently.  

    1. Digit span recall: The clinician recites a series of numbers and asks the patient to repeat them all in the same order.  Normally, people should be able to repeat 7 numbers in a row without errors.  It is considered abnormal when one cannot repeat more than 5 correctly. 

    2. Backwards digit span:  This is similar to the digit span recall, except that the patient is asked to repeat the numbers in reverse order.  Normally, a person should be able to do this correctly with 4 numbers or more. 

    3. Backwards word recall:  The patient is asked to spell a word backwards, such as world, or to recite the names of the months in reverse order.  Normally, people should be able to do these tasks correctly. 

    4. Serial calculations:  The patient is asked to start from the number 100 and subtract 7, and then continue subtracting 7's from each subsequent number.  Normally, people should be able to do this without calculation errors. In cases where a person has a low educational background, or feels very anxious about calculations, they can be asked to start from the number 20 and subtract by 3's. 

    5. Identifying a letter in a series:  The patient is read a series of letters and must raise their hand whenever they hear the letter A.  Normally, people should be able to do this task without errors. 

  2. Testing executive functions: 

    1. General observations: The clinician observes the patient's hygiene, grooming, social interactions and the presence of any odd behaviors.  Problems in any of these areas suggests deficits in a part of the executive system called the the orbitofrontal system, which is involved in self-monitoring, social judgment and inhibiting impulses. 

    2. Patient's subjective reports:  The clinician asks the patient about his or her overall level of motivation and interest in various activities, and assess to what extent the patient seems invested versus apathetic.  A lack of motivation or interest can be a symptom of Depression, but if these deficits do not seem to be linked to the person's mood, then they may reflect a problem with the medial frontal system. 

    3. Clock drawing: The patient is asked to draw a clock with all the numbers showing and with the hands of the clock indicating the hour of ten past eleven.  Normally, a person should be able to draw this without any errors. Problems with clock drawing may reflect deficits in planning, organization and rule monitoring (which are all mediated by the dorsolateral system), as well as working memory and functions of the visuospatial system. 

    4. Set test:  The patient is asked to name all the fruits, animals, colors and towns that they can, one category at a time.  Normally, a person should be able to name at least 10 items for each category.  Naming less than 25 in total for all four categories suggests that there is a problem with the person's ability to retrieve and organize information, which are functions of the dorsolateral system. 

    5. Verbal and drawing fluency:  The patient is asked to name as many words as they can that start with a particular letter, in 60 seconds.  Alternatively, the person can be asked to draw as many different designs as they can by using 4 lines per design, also in 60 seconds.  In both cases, a person should normally be able to provide at least 10 words or designs in the 60 seconds.   Problems with this task suggest that the person has deficits in their ability to organize, plan and retrieve information, which are functions of the dorsolateral system. 

    6. Trail-making test:  In Part A of this test, the person is given a sheet of paper with a bunch of numbers written in different spots on the page, the person must draw a line connecting the numbers in order; this part mainly tests attention.  In Part B, a person is given a page with numbers and letter and must now draw a line that connects the numbers and letters in order, alternating between a number and a letter (ie.  A1 B2 C3 . . .). Problems performing Part B suggest deficits in rule-adherence and set-shifting, which are dorsolateral system functions. 

    7. Luria test: The clinician shows the patient a series of alternating hand positions (eg: fist closed fist open with palm down fist open with palm up) and asks the patient to repeat this sequence quickly as many times as they can.  People who have a deficit in set-shifting, which is a dorsolateral system function, will tend to repeat the same hand position rather than alternating between the different positions, which is a problem called perseveration. 

    8. Go/ No-go test:  The clinician instructs the patient that when the clinician claps once the patient does not clap, but that when the clinician claps twice the patient should clap twice.  If the patient has a problem with their dorsolateral system, then they will tend to repeat what the clinician does rather than follow the rules of the task. 

  3. Testing long-term semantic memory:  People with deficits in this area will have problems naming objects. 

  4. Testing speed of processing:  A slow processing speed becomes obvious if the person seems to be taking a long time to perform any of the tasks described above. 

 

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of Schizophrenia

Overview of Causes