Neuropsychological deficits in adults with neurofibromatosis type 1.

Objectives: To examine neuropsychological deficits in adults with Neurofibromatosis type 1 (NF1) with and without an affective mental disorder (i.e. dysthymia).

Material And Methods: Seventy adult NF1 patients were followed-up after a 12-year period. Of 65 patients assessed earlier with the Comprehensive Psychopathological Rating Scale (CPRS), 19 patients had died. The remaining patients were assessed by the CPRS with the exception of 4 patients, and were psychiatrically diagnosed according to DSM III-R. Twelve patients were excluded because of advanced age, and psychiatric illness other than affective disorder. The remaining 30 NF1 patients (7 with affective disorder and 23 psychiatrically healthy), and a control group of 23 normal adults were assessed on a variety of neuropsychological tests.

Results: Results indicated NF1-related deficits in inductive reasoning, visuoconstructive skill, visual and tactual memory, logical abstraction, coordination, and mental flexibility, although basic motor speed and vocabulary were not affected by NF1. An affective disorder exacerbated the neuropsychological deficits associated with NF1 only with regard to tests assessing motor functions.

Conclusions: NF1 results in a relatively global cognitive impairment among adults, and additional depressive symptoms appear to slow down basic motor processes. It was speculated that the NF1-related cognitive deficits may partly result from white-matter lesions in subcortical brain areas, due to proliferation of glial tissue, aberrant myelination or hamartomas.