The wave of change (nervous impulse) induced in a neuron by advent of a stimulus is after all only a sudden augmentation of an activity continuous within the neuron - a transient accentuation of one (the disintegrative) phase of the metabolism inherent in and inseparable from its life.
The long-continued incitement to catabolism of the waking day thus of itself predisposes the nerve cells towards rebound into the opposite phase; the increased catabolism due to the day's stimuli induces increase of anabolism, and though recuperation goes on to a large extent during the day itself, the recuperative process is slower than, and lags behind, the disintegrative.
The non-sensitiveness of a cell to a toxic body when brought into immediate relationship cannot, however, be explained further than by saying that the disintegrative changes which underlie symptoms of poisoning are not brought about.
Childhood disintegrative disorder is extremely rare, relative to the other pervasive developmental disorders.
For example, for childhood disintegrative disorder to be diagnosed, symptoms must be preceded by at least two years of normal development and onset of decline and regression must occur prior to age 10 years.
