Lee P J, Amos A, Robertson L, Fitzgerald B, Hoskin R, Lilburn M, Weetch E, Murphy G
Charles Dent Metabolic Unit, National Hospital for Neurology & Neurosurgery, London, UK.
J Neurol Neurosurg Psychiatry. 2009 Jun;80(6):631-5. doi: 10.1136/jnnp.2008.151175. Epub 2009 Feb 9.
Although early diagnosis and treatment in phenylketonuria (PKU) leads to excellent outcomes, a population of adults born before the introduction of newborn screening exists. They can have severe intellectual disabilities and behavioural problems, and are often dependent on full-time carers. Anecdotal evidence suggests that a diet that lowers blood phenylalanine concentration can have significant benefits upon behaviour.
A prospective double-blind randomised placebo-controlled crossover trial of phenylalanine-restricted diet was performed in a group of 34 adults (aged 21-61 years, median 49) with late diagnosed PKU with severe challenging behaviour.
Only 17 completed the 60 week study: seven withdrew before the end of the baseline period; five withdrew during the first diet period; five withdrew during the second diet period (after moving into placebo phase). The mean (SD) blood phenylalanine was 1570 (222) micromol/l during baseline, 553(158) mumol/l during the active phase and 1444 (255) micromol/l during the placebo phase. In the 22 participants exposed to both active and placebo phases, no differences were demonstrated in behaviour assessed by the Aberrant Behavior Checklist and Vineland Adaptive Behavior Scales, behaviour diaries or on video analysis of direct observations. However, 76% of carers' comments were scored as positive during the active phase, compared with 54% during the placebo phase (chi(2) = 38.06, p<0.001).
There are significant challenges in studying people with intellectual disabilities and considerable difficulties in instituting phenylalanine-restricted diet in this population. However, if attempted, there are potential benefits to quality of life for the individuals with PKU and their carers.
尽管苯丙酮尿症（PKU）的早期诊断和治疗可带来良好预后，但仍有一部分成年人是在新生儿筛查引入之前出生的。他们可能有严重的智力残疾和行为问题，并且常常依赖全职护理人员。轶事证据表明，降低血液苯丙氨酸浓度的饮食对行为可能有显著益处。
对一组34名患有严重挑战性行为且PKU诊断较晚的成年人（年龄21 - 61岁，中位数49岁）进行了一项关于限制苯丙氨酸饮食的前瞻性双盲随机安慰剂对照交叉试验。
只有17人完成了为期60周的研究：7人在基线期结束前退出；5人在第一个饮食期退出；5人在第二个饮食期（进入安慰剂阶段后）退出。基线期血液苯丙氨酸平均（标准差）浓度为1570（222）微摩尔/升，活跃期为553（158）微摩尔/升，安慰剂期为1444（255）微摩尔/升。在22名同时经历活跃期和安慰剂期的参与者中，通过异常行为检查表、文兰适应行为量表、行为日记或直接观察视频分析评估的行为没有差异。然而，活跃期护理人员的评论中有76%被评为积极，而安慰剂期为54%（卡方 = 38.06，p < 0.001）。
研究智障人群存在重大挑战，在这一人群中实施限制苯丙氨酸饮食也有相当大的困难。然而，如果尝试这样做，对于PKU患者及其护理人员的生活质量可能有潜在益处。
