Cognitive and Psychosocial Functioning of Patients with Congenital Nephrogenic Diabetes Insipidus
| Title: | Cognitive and Psychosocial Functioning of Patients with Congenital Nephrogenic Diabetes Insipidus |
|---|---|
| Authors: | Hoekstra, J.A.; van Lieburg, Angenita; Monnens, Leo A.H.; Hulstijn-Dirkmaat, G.M.; Knoers, Nine |
| Publisher: | American Journal of Medical Genetics |
| Date Published: | January 02, 1996 |
| Reference Number: | 36 |
Mental retardation (MR) is generally considered one of the main complications of congenital nephrogenic diabetes insipidus (NDI). However, psychometric studies of NDI patients are scarce and outdated. In the present study, 17 male NDI patients underwent psychological evaluation. Total intelligence quotient of 14 patients was within (n = 13) or above (n = 1) the normal range, 1 patient had an intelligence score between -1 and -2 standard deviations (S.D.) and 2 young patients had a general cognitive index more than 2 S.D. below the norm. Attention deficit hyperactivity disorder criteria were met by 8 out of 17 patients and scores on short-term memory were low in 7 out of 10. No relation between test performances and age at diagnosis or hypernatremia could be found, with the exception of a negative correlation between age at start of therapy and verbal IQ in one age group. Although several explanations for an association between MR and NDI can be postulated, it seems that the current prevalence of MR among patients with this disease is considerably lower than suggested in literature.
This translation by the NDI Foundation is to assist the lay reader. To provide a clear, accessible interpretation of the original article, we eliminated or simplified some technical detail and complicated scientific language. We concentrated our translation on those aspects of the article dealing directly with NDI. The NDI Foundation thanks the researchers for their work toward understanding and more effectively treating this disorder.
© Copyright NDI Foundation 2007 (JC)
The researchers included as variables the type of mutation in each of the patient's V2R gene, the age the patient was diagnosed for NDI, the maximum blood sodium level recorded in each patient, and the number of months each spent in the hospital the first two years of his life because of dehydration. The group was tested for their total intelligence quotient, verbal IQ, performance IQ, and attention capacity.
Except for a finding that there was a significant negative correlation between verbal IQ and age at start of NDI therapy for the younger age group (ages 7 to 15), there was no significant correlation between any variable and level of intelligence. Test results showed two patients were mentally retarded, one patient had a slightly less than average IQ, 13 patients had a normal range of intelligence, and one had a high intelligence level.
However, the group had test scores indicating low concentration, high distractibility and a high prevalence of attention deficit hyperactivity disorder. Generally, these deficits have been attributed to dysfunction of the frontal lobe, a region which, in NDI patients, is frequently affected with calcifications. There was a general lack of social activity amongst the patients that their parents associated with their children's tiredness. Parents reported that their NDI children preferred to play alone and that the excessive thirst and need to urinate associated with NDI seemed to hamper their children's social interaction.
That the majority (82%) of the group of NDI patients aged three to thirty years had an intelligence within the normal range indicates that, possibly as a result of increased knowledge and better treatment of the disease, MR can no longer be regarded as a clinical hallmark of NDI.