Bradley Elspeth A, Thompson Ann, Bryson Susan E
Department of Psychiatry, University of Toronto.
Can J Psychiatry. 2002 Sep;47(7):652-9. doi: 10.1177/070674370204700707.
There are few Canadian prevalence studies of mental retardation (MR); those that do exist were conducted prior to the era of community integration. We undertook a population-based study to explore mental health disturbances in young persons with MR. The first requirement was to identify a population with MR and to establish its prevalence. Here, we report data on the prevalence of MR in a population aged 14 to 20 years.
We conducted the study in the Niagara Region of Ontario, which has a population base of around 400,000. Researchers worked closely with schools and with agencies providing services to persons with MR to identify the study group. We confirmed the functioning level of participants through standard tests of nonverbal intelligence and receptive language; teachers and other service personnel provided information relevant to the estimation of nonparticipants' functioning level.
We identified 255 individuals as having MR (IQ < or = 75). Of these, 171 chose to participate (defined as "participants with MR"; the remaining 84 were "nonparticipants with MR"). Thus, the participation rate was 67% (171/255). Participants and nonparticipants with MR did not differ on age, sex, or IQ, although there were more nonparticipants in the lower social strata. Overall prevalence for MR was 7.18/1000. For mild mental retardation (MMR; that is, IQ = 50 to 75), prevalence was 3.54/1000, and for severe mental retardation (SMR; that is, IQ < 50), it was 3.64/1000.
Our prevalence estimate for SMR is similar to rates from previous studies conducted worldwide. Our estimate for MMR parallels the lower rates found in Scandinavian countries and contrasts with the higher rates generally reported in the US.
加拿大关于智力迟钝（MR）的患病率研究较少；现有的研究是在社区融合时代之前进行的。我们开展了一项基于人群的研究，以探索患有MR的年轻人的心理健康障碍。首要任务是确定患有MR的人群并确定其患病率。在此，我们报告14至20岁人群中MR患病率的数据。
我们在安大略省的尼亚加拉地区开展研究，该地区人口约40万。研究人员与学校以及为患有MR的人提供服务的机构密切合作，以确定研究组。我们通过非语言智力和接受性语言的标准测试来确认参与者的功能水平；教师和其他服务人员提供了与估计非参与者功能水平相关的信息。
我们确定255人患有MR（智商≤75）。其中，171人选择参与（定义为“患有MR的参与者”；其余84人为“患有MR的非参与者”）。因此，参与率为67%（171/255）。患有MR的参与者和非参与者在年龄、性别或智商方面没有差异，尽管社会阶层较低的非参与者更多。MR的总体患病率为7.18/1000。轻度智力迟钝（MMR，即智商为50至75）的患病率为3.54/1000，重度智力迟钝（SMR，即智商<50）的患病率为3.64/1000。
我们对SMR的患病率估计与之前全球范围内进行的研究结果相似。我们对MMR的估计与斯堪的纳维亚国家发现的较低患病率相似，与美国普遍报告的较高患病率形成对比。
