Assessment

1. Assessment • Aims and Objectives By the end of this lecture you will have learned: • Why an accurate assessment and interpretation of cognitive deficits is important • Some of the problems involved in making inferences about cognitive function from neuropsychological assessments • An overview of the cognitive domains commonly assessed • Suggested reading • Lezak, M (1995).Neuropsychological assessment. Chs 4-6 • Required reading • Benton, AL (1994). Neuropsychological Assessment. Annual Review of Psychology, 45: 1-23

2. Assessment “…neuropsychologicl assessment relies almost entirely on tests, i.e. the elicitation of specific behavioural responses to specific stimuli under controlled conditions.” Benton, 1994. "accurate & systematic assessment of [a] ...disorder is vital both to the researcher and the clinician" (Parkin & Leng, 1993, p.17) Goals of a clinical neuropsychological assessment • Establish pathology (~diagnosis) • Characterise cognitive deficit • Measure change • The assessment will vary depending on the goal • CNs mainly interested in 2.

3. Assessment Why is accurate and systematic assessment important? • Gives objective evidence for the range and severity of problems exhibited • The use of standardised procedures allows comparison across patients and across different laboratories • Assessment can establish which functions are spared - important for rehabillitation. CNs are mainly interested in patients with discrete dysfunctions. The reality is that for most brain damaged patients several functional and behavioural systems are imaired

4. Assessment Neuropsychological test batteries: • Consist of several tests covering a range of domains • E.g. Luria-Nebraska, Halstead-Reitan, CANTAB • Mainly used as diagnostic tools • Advantages: • Tests cover broad spectrum of cognitive functioning • The use of standardised procedures allows comparison across patients and across different laboratories • Offer reliable scoring methods • Disadvantages • Time consuming and too crude • Some tests will be redundant • Reduces flexibility - tests not geared to deficits • Reduces exploration / hypothesis testing / test development

5. General Procedures • NP testing involves a balancing act between achieving OPTIMAL and STANDARD testing conditions • Always aim to obtain the best performance the patient is capable of producing. BUT • Standardised admin is necessary for many tests, and allows individual differences to be meaningfully interpreted. • Two aims sometimes conflict. • Standard conditions often result in standoffish and “robotic” NPs.

6. Interpreting NP tests • NP tests produce both quantitative and qualitative data: • Most NPs rely on both approaches to some extent TEST SCORES: • Raw scores rarely used - many NP tests have standardised scaled scores • Standardised scores based on normal distribution (e.g. WAIS). • Many novel tests used by CNs are unstandardised

7. Interpreting NP tests CUTTING SCORES: The score which differentiates “organic” patients from others with the fewest instances of error on either side. • Often the degree of impairment is important, not simply whether or not it is “significant”. • Important to take into account premorbid abilities - e.g. normal performance on some tests for a previously high-achieving brain-damaged person may indicate deterioration. PATTERN ANALYSIS: The comparison of scores from a variety of different NP tests.

8. Issues concerning neuropsychological inference • The concept of “intelligence” • When is a deficit a deficit? • Emotionality / Personality • How do changes (eg depression) affect NP performance? • Age effects • How does age affect NP performance? • Malingering • Are the observed NP deficits real? • Practice effects • How meaningful is repeated testing?

9. The concept of Intelligence • There is no such “thing” as IQ • “IQ Scores” reflect performance on a variety of tests requiring a variety of different cognitive functions • IQ scores do not predict lesion size or site. • “composite scores of any kind have no place in neuropsychological assessment” Lezak, 1995. • However, within individuals cognitive performance on a variety of tests tends to converge at a similar level • In assessing a cognitive “deficit” the performance on other tests must be considered. • Individual IQ subtests often used to test certain broad categories of cognitive abilities (e.g “construction”). • Premorbid / current IQ difference may be informative • Some measure of IQ nearly always reported

10. Personality / Emotionality • Changes can be a direct consequence of brain disease • “Facetiousness” following frontal lobe lesions Or • “Normal” response to current situation • Post-psychotic depression • Depression post stroke • Most often probably a combination These changes can effect NP performance

11. Age effects • Age effects on memory observable at 40. • Important to include age matched controls • Are deficits related to “speed of processing”? • Many standard NP tests use age-scaled scoring

12. Malingering • Can be for financial gain (medico-legal cases - compensation neurosis) • Pathological (Munchausen Syndrome) • Personal (e.g. faking amnesia to escape consequences of actions) • Various tests developed to reveal malingering • New ones developed all the time as malingerers become more sophisticated

13. Malingering • Attempts to detect malingering generally rely on revealing inadequate knowledge of how a true patient would perform. • E.g. some amnesia malingerers score less than chance on recognition tests • Coin-in-the-hand Test (Kapur) • Simple bedside test where the P is told that E will hide a coin in their hand and put their hands his/her back with P having to try to remember which hand it was - the memory element is stressed • According to Kapur, amnesics got 10/10 on this task and yet malingerers perform at or below chance

14. Practice effects • Change measures are important in NP - e.g. tracking a neurodegenerative illness, or pre-post surgery comparisons • Practice effects can be reduced by parallel batteries • Statistical techniques (control change) • BUT - “novelty” may be crucial factor in some tests (e.g. executive) • Not clear that patients adopt the same strategies when repeating tests

15. Classes of cognitive functions (Completely arbtrary, but seems to guide NP testing) • “receptive functions” • perception - mainly visuoperception • E.g. Agnosia • “expressive functions” • mainly speech, also action • E.g. Apraxia, aphasia • Learning & Memory • Short term / longterm, encoding / retrieval etc • E.g. Amnesia • Executive Functions • Planning, decision making, allocation of attention etc • E.g. Dysexecutive syndrome