Cognitive, sensory, and psychosocial characteristics in patients with Bardet-Biedl syndrome

Abstract

Forty-two patients with a clinical diagnosis of Bardet-Biedl syndrome ages 2-61 years were given a neuropsychological test battery to evaluate cognitive, sensory, and behavioral functioning. These tests included the Wechsler scales of intelligence, Rey Auditory Verbal Learning Test, Boston Naming Test, D-KEFS Verbal Fluency Test, D-KEFS Color-Word Interference Test, D-KEFS Sorting Test, Wide Range Achievement Test: Math and Reading Subtests, Purdue Pegboard, The University of Pennsylvania Smell Identification Test, Social Communication Questionnaire, Social Responsiveness Scale, and Behavior Assessment System for Children, Second Edition, Parent Rating Scale. On the age appropriate Wechsler scale, the mean Verbal Comprehension was 81 (n = 36), Working Memory was 81 (n = 36), Perceptual Reasoning was 78 (n = 24) and Full Scale IQ was 75 (n = 26). Memory for a word list (Rey Auditory Verbal Learning Test) was in the average range with a mean of 89 (n = 19). Fine motor speed was slow on the Purdue with mean scores 3-4 standard deviations below norms. All subjects were microsmic on the University of Pennsylvania Smell Identification Test. Of these 42 patients, only 6 were able to complete all auditory and visual tests; 52% were unable to complete the visual tests due to impaired vision. A wide range of behavioral issues were endorsed on questionnaires given to parents. Most had social skill deficits but no pattern of either externalizing or internalizing problems. We identify a characteristic neuro-behavioral profile in our cohort comprised of reduced IQ, impaired fine-motor function, and decreased olfaction.

Keywords: Bardet-Biedl syndrome; Intellectual disability; brain development; olfaction; psychometric testing.

Fig. 1

Average composite scores of males, females, and combined group scores on Wechsler IQ tests. Black line represents the average score in the normal population (100). The data show that all sub scales for both genders are substantially lower than normal.

Fig. 2

University of Pennsylvania Smell Identification Test score correlations with IQ scores. (A) Full scale IQ; (B) Verbal Comprehension Index (VCI); (C) Working Memory Index (WMI); (D) Perceptual Reasoning Index (PRI); (E) Processing Speed Index (PSI).

Fig. 3

Average T scores on the Social Responsiveness Scale (SRS). The area between the black bars represent the average score range in the normal population (40-60).

Fig. 4

Average T scores on the Behavior Assessment System for Children, Second Edition (BASC-2) Parent Rating Scale. The area between the black bars represent the average score range in the normal population (40-60).