Appendix e-1

Neurolinguistic and neuropsychological assessment

All subjects completed the following battery of detailed neurolinguistic and general neuropsychological tests.

Spontaneous speech. The number of speech production errors produced per minute was recorded. Due to the difficulty of reliably classifying speech production errors as phonemic (errors in the selection of speech sounds to be executed) versus phonetic or apraxic (errors in the execution of a programmed speech sound) these error types were not analyzed separately. Speech was also analyzed for word-finding pauses: the distribution of inter-word intervals in the speech sample was obtained using a customised routine running under Matlab® which measured intervals between vocalizations (whether within or between sentences). Patients who have difficulty finding words often use more high frequency (common) words and less low frequency (less common) words and so we investigated the mean frequency rating of the nouns and verbs used by patients in spontaneous speech. Frequency ratings were based on the CELEX database with scores converted to a mean log score as word frequencies from this scale varied between 10 and 100,000. All analyses were performed blind to the diagnosis.

Naming and single word comprehension. Naming was assessed using the Graded Naming Teste1. As many patients were likely to score near floor on this difficult test (first few items are kangaroo, scarecrow and buoy), a simple naming test containing 20 items was also used (first few items are chair, shoe and pen). Single word comprehension was tested with: 1) a noun synonyms teste2 (e.g., does javelin mean the same as shield or spear?); 2) a verb synonyms teste3 (e.g., does to annihilate mean to abandon or to destroy?), and 3) a word-picture matching test (shortened version of the British Picture Vocabulary Scalee4) in which patients had to match a word to one of four pictures. Verbal material in each of these word comprehension tests was presented both visually and aurally.

Verbal short-term memory, sentence comprehension and grammar. Maximum forward digit span (allowing two attempts at each level) was recorded. Sentence comprehension and verb tense comprehension were subsequently assessed using the following tests: 1) a modified version of the PALPA55 spoken sentence-picture matching (three alternative forced choice) teste5 comprising 24 sentences testing comprehension of reversibility (subject:object relations, of the kind ‘The girl is washing the dog’) and active/passive constructions; 2) a spoken sentence-picture matching (two alternative forced choice) test of verb tense comprehension that was an adapted version of the Lesser Syntax teste6,e7 comprising 20 pairs of pictures which differ in whether the agent is doing something/has done something (present/past comparison, 10 items) or whether the agent is doing something/is about to do something (present/future comparison, 10 items).

Speech repetition. Three tests of repetition were performed: 1) 60 single words taken from a larger corpuse8, consisting of 20 one-syllable, 20 two-syllable and 20 three-syllable words (in each of the sets of 20 words, 10 words were of high frequency and 10 of low frequency); 2) 20 nonwords comprising 10 three-letter consonant-vowel-consonant words and 10 words of one to three-syllables taken from the PALPA8 nonword repetition taske5; and 3) 20 sentencese8 comprising A) 10 sentence clichés (e.g. “As blind as a bat”, “A flash in the pan”), and B) 10 novel sentences (e.g. “She met me at the airport”, “He mended the plug”). Sentence length varied between three and seven words; there was no significant difference in word number between the clichés (4.4 words per sentence) and novel sentences (4.8 words per sentence).

Reading and spelling. Three reading tests were administered: 1) the Schonell Reading Teste9, a mixture of regular and irregular words of varying difficulty (score out of 100); 2) an irregular word reading test (score out of 30); and 3) the Graded Difficulty Nonword Reading Teste10 (score out of 20). Spelling was assessed using the Graded Difficulty Spelling Teste11.

Other cognitive domains. Tests of executive function (Nonverbal fluency task from the D-KEFS executive function batterye12), episodic memory (Camden Pictorial Recognition Memory Teste13), visuoperceptual skills (the Object Decision subtest of the Visual Object and Space Perception Battery, VOSPe14) and limb praxis (Apraxia Battery for Adults-2e15) were also administered.

e-References

e1. McKenna P, Warrington EK. Testing for nominal dysphasia. J Neurol Neurosurg Psychiatry 1980;43 (9):781–8.

e2. Warrington EK, McKenna P, Orpwood L. Single word comprehension: a concrete and abstract word synonym test. Neuropsychol Rehabil 1998;8:143–54.

e3. Manning L, Warrington EK. Two routes to naming: A case study. Neuropsychologia. 1995; 34(8):809-817.

e4. Dunn LM, Dunn LM, Whetton C, Pintilie D. British Picture Vocabulary Scale. NFER-Nelson, 1982.

e5. Kay J, Lesser R, Coltheart M. Psycholinguistic Assessments of Language Processing in Aphasia (PALPA). Hove: Erlbaum, 1992.

e6. Lesser R. Verbal comprehension in aphasia: an English version of three Italian tests. Cortex. 1974 Sep;10(3):247-63.

e7. Parisi D, Pizzamiglio L. Syntactic comprehension in aphasia. Cortex. 1970 Jun;6(2):204-15.

e8. McCarthy R, Warrington EK. A two-route model of speech production. Evidence from aphasia. Brain. 1984 Jun;107 ( Pt 2):463-85.

e9. Schonell F. Backwardness in the basic subjects. London: Oliver & Boyd; 1942.

e10. Snowling MJ, Stothard SE, McLean J. Graded nonword reading test, Thames Valley Test, Bury St. Edmunds, UK; 1996.

e11. Baxter DM, Warrington EK. Measuring dysgraphia: a graded-difficulty spelling test. Behav Neurol 1994;7 (3–4) :107–16.

e12. Delis D, Kaplan E, Kramer J. Delis-Kaplan executive function scale. San Antonio, TX: Psychological Corporation, 2001.

e13. Warrington EK. The Camden Memory Tests. Psychology Press, 1996.

e14. Warrington EK, James M. The visual object and space perception battery. Bury St Edmunds, UK: Thames Valley Test Company, 1991.

e15. Dabul B. Apraxia Battery for Adults, Second ed. Austin, Tx: Pro-Ed, 2000.