Early studies of cognitive function suggested that all people with Lesch-Nyhan disease had severe mental retardation. As a result, many pediatrics books and doctors say that individuals Lesch-Nyhan disease are severely retarded. This is not true. Recent studies have suggested much less severe cognitive disability. IQ testing reveals a wide range in scores with some falling in the normal range. The IQ scores usually fall between 60-70, which is classified as mild or moderate cognitive impairment.
More importantly, recent studies have addressed different cognitive domains, such as memory or language skills, to determine the reason IQ scores are low. As a group, individuals with Lesch-Nyhan disease have relatively good memories and language. But their attention spans are terrible, and they have difficulty with complex planning and predicting the consequences of future events. These limitations make it hard for them to get through the usual lengthy cognitive testing sessions, and to learn in normal school environments. IQ scores and school performance improve if educational opportunities and tests are tailored to their weaknesses.