A Randomized Placebo-Controlled Study of Lovastatin in Children With Neurofibromatosis Type 1

A computerized test of visuospatial learning. Participants had to remember patterns associated with different locations on the screen, and during the test phase, as each pattern is presented, point to the appropriate location. The test starts at a very simple level and gradually increases in difficulty. Higher number of errors indicates poorer performance. Scale does not have a maximum range.

Score! is a measure of sustained attention. Participants were required to silently count a series of aurally presented tones and say the total number of tones counted at the end of each trial. The number of tones ranged from 9 to 15, with a total of 10 trials (range 0-10). Higher values represent better performance.

A computerized measure of spatial working memory. This task assessed the participant's ability to retain spatial information and to manipulate remembered items in working memory.

In this test, participants were shown an array of boxes on a computer screen and they were required to search through the boxes for hidden tokens. One box at a time was touched until a blue token was found inside. Participants then commenced a new search for the next token. The key instruction was that, once a token had been located, that box would not be used again to hide another token.

Unit of measure was between search errors, determined by the number of boxes a participant reopens in which a token had previously been found. Higher score indicated poorer performance. Scale does not have a maximum range.

A computerized measure of spatial planning based on the "Tower of London" test. It required participants to move balls in a lower display to match a pattern shown in the upper display in a certain number of moves.

More specifically, the participant was shown two displays containing three coloured balls. The displays were presented in such a way that they could be perceived as stacks of coloured balls held in socks suspended from a beam. The test administrator first demonstrated to the participant how to move the balls in the lower display to copy the pattern in the upper display and completed one demonstration problem, where the solution required one move. The participant then completed problems that increased in difficulty, from one through to five move problems.

The unit of measure was the mean number of moves taken to complete a problem that could not be completed in less than five moves. The higher the score, the poorer the performance (range 5-12).

A computerized measure of inhibitory control. The participant quickly responded to an arrow stimulus by pressing one of two buttons (left or right), depending on the direction in which the arrow pointed on the screen. If an audio tone is present, the subject was supposed to withhold the response.

The difficulty of the task was manipulated by altering the delay before a stop signal (auditory tone) was presented, known as the stop signal delay. The outcome from this measure was stop signal reaction time (last half of test), which was computed by subtracting the mean stop signal delay at which the participant was able to stop on 50% of trials from the mean reaction time on go trials. Poorer response inhibition was reflected by a larger stop signal reaction time. Scale does not have a maximum range.

Sky Search is a measure of selective visual attention. Participants were presented with a A3 sheet with target stimuli (spaceships in identical pairs) randomly distributed among many distractors (spaceships in non-identical pairs). They were required to circle as many of the targets as possible as quickly as possible. The outcome measure (attention score), was a timing score reflecting the average time taken per target found. Higher scores represent poorer performance. Raw data are reported. Scale does not have a maximum range.

Sky Search DT is a test of divided attention. Children completed a parallel version of the Sky Search subtest while at the same time, silently counted the number of tones in a similar way to the Score! subtest. Higher scores represent poorer performance. Raw data are reported. Scale does not have a maximum range.

Creature Counting is a measure of attentional control. Participants were required to count "creatures" from top of the page to the bottom, using arrows as cues to switch from counting up to counting down (and vice versa). There were seven testing trials. The outcome variable was the total number of correct trials (range 0-7). Higher scores represent better performances.

A computerised measure of impulse control. Letters were presented serially on a screen in a random order. All letters were considered target stimuli, except for the letter 'X' which is a non-target stimulus. Participants responded to target stimuli by pressing the space bar of a computer keyboard (90% of the stimuli) while withholding responses to non-target stimuli (10% of the test). Commission errors represented the number of times a participant incorrectly responded to the non-target (letter 'X'). T-scores are reported, as generated by the test software. Higher scores indicate poorer performances.

A computerised measure of vigilance and concentration. Letters were presented serially on a screen in a random order. All letters were considered target stimuli, except for the letter 'X' which is a non-target stimulus. Participants responded to target stimuli by pressing the space bar of a computer keyboard (90% of the stimuli) while withholding responses to non-target stimuli (10% of the test). Omission errors represented the number of times a participant fails to respond to target letters (all other than 'X'). T-scores are reported, as generated by the test software. Higher scores indicate poorer performances.

Parent rated inattentive ADHD symptoms, based on Diagnostic and Statistical Manual of Mental Disorders criteria, 4th edition. T-scores are reported. Higher scores indicate increased ADHD-related symptoms. A score below 60 is considered healthy, 61-65 a possible significant problem, and 66+ is considered a significant problem.

Parent rated hyperactive/impulsive ADHD symptoms, based on Diagnostic and Statistical Manual of Mental Disorders criteria, 4th edition.T-scores are reported. Higher scores indicate increased ADHD-related symptoms. A score below 60 is considered healthy, 61-65 a possible significant problem, and 66+ is considered a significant problem.

A measure of verbal fluency. Participants were required to spontaneously produce as many words as they could, beginning with a designated letter in 60 seconds. Three letters were used. Higher scores represent better performances. Raw data are reported summing total words generated for all three letters. Scale does not have a maximum range.

A test of visuospatial judgement. The test measured the participant's ability to match the angle and orientation of lines in space. There were 30 trial in total. Correct response in a trial was awarded one point (range 0-30). Higher scores represent better performances. Raw data are reported.

A parent-rated questionnaire of executive behaviour assessing behavioral regulation (inhibit, shift, emotional control) and metacognition (initiate, working memory, plan/organize, organization of materials, self-monitoring). T-scores for the Global Executive Composite (overall summary score) are reported. Higher scores indicate poorer executive behaviors.

A measure of visuoperceptual organization. Participants were required to rebuild an item puzzle based on disassembled pieces. Age scaled scores are reported, which have a population mean of 10 and standard deviation of 3 (range 1-19). Higher scores indicate better performances.

A parent-reported questionnaire assessing internalizing behaviors of anxiety, depression and somatization. T-scores are reported. Higher scores indicate increased internalizing behaviors. A score below 60 is considered healthy, 61-65 a possible significant problem, and 66+ is considered a significant problem.

A self-reported questionnaire assessing internalizing behaviors such as anxiety and depression. T-scores are reported. Higher scores indicate increased internalizing behaviors. A score below 60 is considered healthy, 61-65 a possible significant problem, and 66+ is considered a significant problem.

Parent-rated questionnaire of psychosocial Quality of Life (including emotional, social and school functioning). Summary scores are reported. Higher scores indicate increased increased quality of life (range 0-100).

Self-rated questionnaire of psychosocial Quality of Life (including emotional, social and school functioning). Summary scores are reported. Higher scores indicate higher quality of life (range 0-100).