Cognition in classic galactosemia: What happens to the developing brain?

Classic galactosemia is a hereditary disorder caused by the body*s inability to
breakdown galactose, a sugar mainly found in milk. A galactose-restricted diet
(soy diet) is the basis of therapy. This, however, does not prevent the
emergence of long-term complications. One of these long-term complications is
related to cognition. Reduced intelligence quotient (IQ) scores as well as
impairments in speech and language have been reported. In fact, ninety percent
of affected children have speech problems, usually diagnosed as Childhood
Apraxia of Speech (CAS) (i.e. an impairment of motor programming of speech
musculature). However, at present, CAS is over-diagnosed. This means that there
are patients that receive a treatment for CAS, while other speech disabilities
are being overlooked and not addressed properly resulting in suboptimal
treatment. Our preliminary research concerning speech shows that syntax (i.e.
grammar and construction of sentences) is a major problem in these children.
The innovative approach in this study, examining the different levels of speech
(e.g. semantic and syntactical speech) in combination with behavioral data and
simultaneous brain activity recordings, aims to elucidate which levels of
speech are specifically impaired in these children. Pinpointing at which level
speech and other cognitive functions are affected is imperative to design
successful treatment approaches with a better outcome.

In this study we aim to elucidate which areas of speech are specifically
affected in children and adolescents with classic galactosemia and to sketch a
profile of the galactosemic patients* general cognitive functions.

Observational case control design consisting of a neuropsychological assessment
and a behavioural paradigm with simultaneous electroencephalographic (EEG)
brain activity recording.

The participants will be asked to visit the Maastricht University Medical
Centre twice (i.e. each visit lasting about two hours). They are expected to
perform several neuropsychological tasks as well as to participate in an EEG
recording. The EEG recording might be experienced as slightly unpleasant at the
most, although there are no adverse reactions expected.

This study will be conducted with minors being the subjects, instead of adults.
The goal of this study is namely to gain more knowledge about the cognitive
abilities of a group of young patients with classic galactosemia. The
examination of the development of these abilities is therein an important and
indispensable part. An adequate description of the development of cognitive
functions is necessary for multiple reasons [see also D8]. First, there is an
ongoing debate as to whether intellectual capacities regress with age. By
taking a broader approach and studying besides intellectual capacities other
cognitive functions as well, we can give a significant contribution solving
this question. Second, virtually all children and adolescents with galactosemia
receive therapy and/or special education because of their cognitive
impairments. A characterization of these impairments and furthermore of the
development of these impairments is therefore indispensable and will contribute
to a (more) optimal treatment. Finally, the fact that children and adolescents
still have the possibility to be treated for their specific problems, because
many functions are still in development, is essential to report as well.