Qualitative aspects of verbal fluency in HIV-associated dementia: a deficit in rule-guided lexical-semantic search processes?
HIV-associated dementia (HAD) is widely considered a "subcortical" dementia that involves a disruption of frontal-basal ganglia circuits. Deficits in verbal fluency are common in HAD; however, the cognitive underpinnings of these deficits are not well understood. To elucidate the cognitive mechanisms underlying the diminished verbal fluency output in HAD, we examined several qualitative aspects of letter fluency in 21 individuals with HAD, 51 nondemented persons with HIV infection (HIV+), and 30 healthy controls (HC) who were comparable for age, education, sex, ethnicity, and estimated premorbid verbal intelligence. The verbal fluency protocols were scored to obtain the total number of correct words, average phonemic cluster size, total number of switches between phonemic clusters, and the proportion of error responses (i.e., intrusions, perseverations, and variants). Consistent with prior research, HAD participants produced significantly fewer total correct words relative to the HC and nondemented HIV+ groups. The HAD group also demonstrated fewer switches and a higher proportion of response errors (especially intrusion errors), but no differences were observed in average cluster size. Findings are interpreted as reflecting a disruption of rule-guided lexical-semantic search strategies in HAD, perhaps mediated by prefrontal-striatal circuit dysfunction, rather than depleted lexical-semantic memory stores.
Woods
Steven Paul
SP
HIV Neurobehavioral Research Center, University of California-San Diego, 150 West Washington Street, 2nd floor, San Diego, CA 92103, USA. spwoods@ucsd.edu
Conover
Emily
E
Rippeth
Julie D
JD
Carey
Catherine L
CL
Gonzalez
Raul
R
Marcotte
Thomas D
TD
Heaton
Robert K
RK
Grant
Igor
I
D015526:AIDS Dementia Complex / Q000150:complications / Q000503:physiopathology*; D000328:Adult; D000704:Analysis of Variance; D003072:Cognition Disorders / Q000209:etiology / Q000503:physiopathology*; D005260:Female; D015658:HIV Infections / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D009483:Neuropsychological Tests; D012016:Reference Values; D012660:Semantics; D014705:Verbal Behavior / Q000502:physiology*; D014706:Verbal Learning / Q000502:physiology*