Young people with dyslexia are lagging far behind their peers when it comes to gaining high-level qualifications, despite managing to keep pace in earlier years, a major new report from Education Scotland has found.

Meanwhile, separate research by a leading dyslexia charity suggests that pupils with the condition are being “significantly disadvantaged” in some authorities, where they do not receive enough support when sitting exams.

Students have broadly similar levels of attainment up to Intermediate 1 (now National 4) or equivalent, but at Intermediate 2 (National 5) and Higher level, a gap of “between 20 and 30 per cent” opens up between those with dyslexia and other pupils, the Education Scotland report says.

Overall, figures from 2011-12 show that students with dyslexia gain a set of qualifications at a level that is less than 60 per cent of the national average, when both the number of qualifications gained and their grades are taken into account. Only 17.1 per cent of students with dyslexia move on to higher education, compared with 40.4 per cent of students with no additional support needs.

Although schools have become better at supporting dyslexic pupils, Education Scotland found that few local authorities had up-to-date figures on the numbers of children affected and some had not even settled on a definition of the condition.

In its own research, published in March, the charity Dyslexia Scotland says that “in a number of authorities pupils are being significantly disadvantaged in examinations”.

Analysis of national data shows that authorities with low identification rates for dyslexia also make fewer requests for special arrangements to support dyslexic pupils in sitting exams. The report says: “Caution must always be exercised when interpreting statistics, but it is difficult to avoid the conclusion that there is inequality here.

“A secondary school pupil with dyslexia in East Renfrewshire or Orkney has, approximately, a five or six times better chance, respectively, of having assessment arrangements made than one in North Lanarkshire and therefore has a better chance of success in examinations.”

According to the research, there is “a degree of consensus” that about 10 per cent of the school population has dyslexia, but in 2013 only 15,368 pupils, or 2.3 per cent, were recorded as having the condition.

Dyslexia Scotland chief executive Cathy Magee flagged up concerns about “the inconsistency and variability of practice” identified in the Education Scotland report and welcomed a recommendation for a “comprehensive dyslexia professional learning package” for teachers.

Eileen Prior, executive director of the Scottish Parent Teacher Council, said: “Parents are continuing to encounter teachers and schools which will not address the needs of their children, causing families untold stress and damaging the learning of young people. This is an unacceptable situation.”

The report - which was carried out on behalf of the Scottish government and was the first national review of education and dyslexia to be undertaken since 2008 - shows that very few authorities know how many staff have taken part in accredited courses to address dyslexia. Some 16 of Scotland’s 32 authorities, meanwhile, have no online material to tell parents about their approach to helping pupils with dyslexia.

The negative emotional impact of inadequate support is also highlighted in the report. One child preparing to start P4 told their parents that they would be “better off without me”, while another young person had twice attempted suicide.

Schools are “generally making good provision” for pupils with dyslexia, the report says. But it has recommendations for improvement: teachers, pupils and parents should receive better advice and guidance; teachers should receive better training and “high priority” should be given to trainees; schools, local authorities and national bodies need to take responsibility for improving educational outcomes; and more reliable information on dyslexic pupils’ needs should be made available.

Bill Maxwell, chief executive of Education Scotland, said that teachers were “better equipped than ever before” to deal with dyslexia but work remained to improve attainment. Education secretary Michael Russell saw “a lot of progress” but said there was “still more that we and others can do”.

Iain Ellis, chair of the National Parent Forum of Scotland, said: “We welcome this report, which indicates that the situation for those who have dyslexia is improving in our schools. Ensuring there is consistent support and good practice to support pupils with dyslexia across all schools and classrooms will continue to improve outcomes for these children and young people.”