Neuropsychological tests

A full neuropsychological evaluation, with several tests for each cognitive domain including attention, memory, language, praxis, visuospatial and executive functions, tailored for the age, education, and general mental status of the patient, is the most appropriate way to assess cognitive functions. However, this is time-consuming and needs special expertise to choose the tests, perform them, and interpret their results. For routine clinical practice, easy-to-administer bedside tests may be sufficient to rapidly assess the cognitive status of the patient. In accordance with the profile of cognitive impairment in PD-D, several simple tests for the most affected cognitive domains can be administered (Table 20.3). These include serial sevens (subtracting 7 from 100 backwards) or months/days recited backwards to assess attention; verbal fluency (both lexical and semantic) and clock-drawing tests for executive functions; copying a three-dimensional cube or intersecting pentagons, mimicking complex hand figures (such as intercalating fingers) to assess visuospatial functions; and simple memory tests such as learning a three- to five-word list or a five-item address, assessing both free recall and recognition (after cueing and after providing alternatives) following sufficient learning trials. The most yielding are probably verbal fluency and clock-drawing tests, which are described below.

The lexical fluency task consists of naming as many words as possible within a minute which start with a certain letter. The letters used in the English language are F, A, and S, names of humans (such as Peter) or geographical places (such as New York) are not allowed. The semantic fluency test requires the naming of as many objects as possible within a minute which belong to a certain semantic category, such as animals or vegetables. In PD patients both tests are sensitive to detect impairment, basically in internally cued search strategies, lexical fluency tapping more frontal functions and semantic fluency more temporal ones. The cut-off scores vary depending on age,

Table 20.3 Neuropsychological tests to evaluate individual cognitive domains

A: Bedside tests

• Attention: serial sevens, months or days backwards

• Memory: learning a three- to five-word list, or a five-item address, with delayed free recall, recall after cueing and recognition

• Executive functions: verbal (lexical and category) fluency, clock-drawing test

• Visual-spatial functions: copying intersecting pentagons or a three-dimensional cube; imitating hand figures such as intercalating fingers

• Language: spontaneous speech (word-finding difficulties, pauses), naming common and rarer objects, understanding complex sentences

B: More comprehensive tests

• Attention: forward and backward Digit Span, continuous performance tests

• Memory: Rey Auditory Learning, California Verbal Learning, Buschke Selective Reminding Tests

• Executive functions: Wisconsin Card Sorting, Stroop test, Tower of London test, Trails A and B

• Visual-spatial functions: Rey-Osterreich Complex Figure, Picture Completion, Recognizing Embedded Figures, Line Orientation and Benton Facial Recognition tests

• Language: Boston Naming Test

culture, and education; usually 12-14 words for each letter or items in each category are regarded as normal. The clock-drawing test is a simple but very sensitive test, it taps executive functions such as planning as well as visuospatial functions. The patient is given an empty circle about 5 cm in diameter on a blank sheet, with the centre and the top marked, and asked to place all the numbers of a clock in the appropriate location and then to draw the arms of the clock to indicate 11:10. The following are evaluated: whether the patient starts with adequate planning by placing 12, 3, 6, and 9 first; whether all the numbers are located in the right place; whether the whole circle is used; and whether 11:10 is correctly indicated.

Examples of more elaborate neuropsychological tests are listed in Table 20.3. These include: forward and backward digit span and computerized continuous performance tests for attention; Wisconsin Card Sorting, Tower of London, or Stroop tests for assessing planning, mental set-building and set-shifting, Trails A and B for psychomotor speed, and set-shifting for the assessment of various components of executive functions; California Verbal Learning, Rey’s 15 words and 15 shapes, or Bushke’s Selective Reminding Test for memory; copying Rey-Osterreich complex figure, picture completion test, recognizing embedded figures, line orientation, and face recognition tests to assess visuospatial functions; and the Boston Naming Test for confrontational naming. The extent of testing and types of tests should be tailored according to the age, intellectual capacity, and general condition of the patient.

 
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