▁result ▁of ▁the ▁changing ▁definition ▁of ▁the ▁dis order , ▁particularly ▁changes ▁in ▁D SM - III - R ▁and ▁D SM - IV . ▁An ▁editor ial ▁error ▁in ▁the ▁description ▁of ▁the ▁P DD - N OS ▁category ▁of ▁Aut ism ▁Spect rum ▁Dis orders ▁in ▁the ▁D SM - IV , ▁in ▁ 1 9 9 4 , ▁in app ropri ately ▁bro aden ed ▁the ▁P DD - N OS ▁construct . ▁The ▁error ▁was ▁corrected ▁in ▁the ▁D SM - IV - TR , ▁in ▁ 2 0 0 0 , ▁revers ing ▁the ▁P DD - N OS ▁construct ▁back ▁to ▁the ▁more ▁restrict ive ▁di agnostic ▁criteria ▁requirements ▁from ▁the ▁D SM - III - R . ▁ ▁Success ively ▁earlier ▁diagn osis ▁in ▁each ▁succeed ing ▁coh ort ▁of ▁children , ▁including ▁recognition ▁in ▁nur ser y ▁( pr esch ool ), ▁may ▁have ▁affected ▁apparent ▁pre val ence ▁but ▁not ▁inc idence . ▁ ▁A ▁review ▁of ▁the ▁" ris ing ▁aut ism " ▁figures ▁compared ▁to ▁other ▁dis abilities ▁in ▁schools ▁shows ▁a ▁corresponding ▁drop ▁in ▁find ings ▁of ▁mental ▁ret ard ation . ▁ ▁The ▁reported ▁increase ▁is ▁largely ▁att rib utable ▁to ▁changes ▁in ▁di agnostic ▁practices , ▁refer ral ▁patterns , ▁avail ability ▁of ▁services , ▁age ▁at ▁diagn osis , ▁and ▁public ▁aw aren ess . ▁A ▁widely ▁c ited ▁ 2 0 0 2 ▁pilot ▁study ▁concluded ▁that ▁the ▁observed ▁increase ▁in ▁aut ism ▁in ▁California ▁cannot ▁be