Generally, in longitudinal analysis, three data points are the minimum required to fit a line while guarding against reversions to the mean. The lead author is currently assessing data with a third longitudinal timepoint of the ADOS severity measure. That said, the research article tried to guard against this problem by defining the minimum amount of change to be considered a reliable change i.e. a Reliable Change Index statistic (RCI; Jacobson and Truax 1991), which is, in Latex: RCI_{{Z\,SCORE}} = \frac{{({\text{ADOS}}\,{\text{CSS}}{\mkern 1mu} {\text{Time}}{\mkern 1mu} 3 - {\text{ADOS}}\,{\text{CSS}}{\mkern 1mu} {\text{Time}}{\mkern 1mu} 1)}}{{\sqrt {2\left( {SD\sqrt {1 - r_{{xy}} } } \right)^{2} } }} which takes into account test-retest reliability correlations.

Roughly speaking, this meant the the change groups ended up changing dX>+2 or dX<-2 on a 0-10 ADOS severity scale (4 is usually the clinical threshold for ASD diagnosis), while the no change group was defined roughly as between -2<dX<+2.

Furthermore, in data I did help analyze which is currently included in a journal submission, the change groups defined here exhibited altered longitudinal trajectories of white matter fractional anistropy and diffusivity, suggesting biological relevance one might not expect with a statistical reversion to the mean.

Camouflage is just one of the potential hypotheses out there, and the one with which I am least familiar. There are ideas about increased social-cognitive abilities in girls, allowing more effective masking/adaption. But it can also be the case that it is not merely camouflaging symptoms, but actually neural adaption and compensation that reduce or even eliminate symptoms. It could be that girls receive more social support than boys, and the one thing we do know about autism during early childhood is that early behavioral interventions can improve quality of life outcomes.

The gender disparity in autism prevalence is one of the big mysteries of autism since genes associated with autism risk are not generally located on the XY sex chromosome. There are a number of hypotheses out there for the disparity of prevalence.

One hypothesis is that the disparity is more apparent than real: That girls are better at masking/adapting to their symptoms, and thus more frequently escape diagnosis. The first step is to determine the extent to which this is true. If true, the underlying mechanism would need to be understood...some have suggested this could be related to greater inter-hemispheric connectivity in girls.

This dataset did not include a controlled therapy intervention. Community therapy of a multitude of varieties probably occurred.