Class_14_Premorbid Ability Flashcards
(10 cards)
speed of decline
can be informative about whether it is normal ageing, or indicate different forms of dementia
- Crystalized ability (e.g., semantic knowledge) is stable
- But more rapid than normal decline fluid ability, or decline in crystalized ability, may indicate pathology.
Other problems with defining ‘normal’ statistically
1.The criteria for ‘abnormal’ is flexible
2.A ‘normal’ average point is not biologically reasonable
3.Race and normative tables are highly controversial
Abnormal SD/percentiles across tests
- Wechsler scales < 2SD (2% of healthy)
- Benton tests < 5th percentile, or 1.65 SD (5% of healthy)
-Halstead–Reitan Battery < 1SD (16% of healthy)
A ‘normal’ average point is not biologically reasonable
- Assuming everybody was average before illness is extremely naïve
- People naturally vary in their cognitive
ability - Socioeconomic factors are very important as is educational access.
Demographic methods of estimating premorbid cognitive ability
Regression equation
- socioeconomic background (or ‘class’)
- education
- age
Hold Cognitive Abilities
verbal (crystalized)
- not sensitive to the illness
No-hold Cognitive Abilities
performance (fluid)
- sensitive to the illness
Lexical word pronunciation
correlate very highly with IQ scores
- estimate a person’s IQ
- unaffected by dementia
- i.e., their premorbid ability.
Limitations of word pronunciation tasks
- Many patients with neurological damage have impaired speech, which may invalidate tests such as the NART.
- some very intelligent people have learnt through reading, and will still tend to mispronounce words
Advantages of lexical-decision tasks
- do not require any articulation skill
- could be used when patients have speech difficulties
- in any language.
- Assessors do not have to listen to every word spoken
- The test can be administered to groups, or online
