Friday, July 29, 2016

Autism in Adults: A Survey - Part 6: Functional Language

This is part 6 of a series on a survey I did in 2012. To get background information, go to part 1. To read an analysis of executive dysfunction in the sample, go to part 2. To read an analysis of alexithymia in autism, go to part 3. To read an analysis of the results from a new questionnaire assessing reaction to eye contact, go to part 4, and to read an analysis of a new questionnaire about autism internal experience, go to part 5. Lastly, to read about independent living skills, go to part 7.

In this section, I discuss responses to several qualitative questions discussing communication ability.

First, I asked about baseline language ability. Written language appeared to be better than speech in both receptive and expressive domains, with 20.5% reporting difficulty with receptive speech and 29.5% with expressive speech, compared to only 9.3% reporting difficulty with reading and 2.3% with writing. Overall, 61.9% had normal baseline language ability, 23.8% had impairment in one area and 14.3% had impairment in two areas, with no participants having three or more areas of impairment. There were significant correlations between expressive and receptive spoken language (r = .413, p = .005) and receptive spoken and written ability (r = .464, p = .002).

Age was correlated with receptive speech (r = .471, p = .002), with an ANOVA finding that 17-24 year olds were more likely to have impairments in receptive language than 36-60 year olds (25-35 year olds were intermediate and didn't significantly differ from either age group). Specifically, 47.1% of 17-24 year olds, 16.7% of 25-35 year olds and none of the 36-60 year olds reported baseline receptive speech issues. In addition, female participants were more likely to have receptive speech issues, with 26.1% of women and 6.2% of men having baseline receptive speech impairment.

In addition, 25% of individuals reported significant variability in their expressive language skills, while 22.7% reported variability in receptive language. In most cases, the trigger for this variability seemed to be overload, emotional distress, fatigue, or distracting stimuli (such as background noise or eye contact). The variability could range from a subjective feeling of greater communication difficulty in certain situations, to becoming temporarily nonverbal. Variability in written language was less common, with only two people reporting variability in writing ability and none in reading ability.

In this sample, 11.4% had variability in expressive or receptive language ability and 18.2% had variability in both receptive and expressive language ability (usually with the same conditions impairing both). Of the two participants with variable writing ability, both lost written and spoken expressive ability under the same conditions. Variability in receptive and expressive language was significantly correlated (r = .689, p = .001). Variability in receptive and expressive language were both more common in women, with 34.8% of women having variable expressive language and 30.4% having variable receptive compared to 6.3% and 12.5% of men.

The individuals with variability in language performance were not necessarily those with poor baseline performance, with no correlation between baseline performance and variability found. Considering all six language problems described so far, only 45.2% of my sample had consistently normal language ability, with 21.4% having one language issue, 26.2% having two language issues and 7.1% having three language issues. None of my sample had more than three of these issues.

There were no correlations between language impairments and AQ total or Reaction to Eye Contact factor scores. However, the only individual with impaired baseline written language had the lowest score on AQ imagination of the sample (scoring 2), and individuals with impaired baseline receptive spoken language scored lower on AQ communication (r = .339, p = .030).

Poor baseline receptive speech was also associated with higher FrSBe total scores (r = .322, p = .043). Variable receptive language was associated with higher scores on FrSBe total (r = .357, p = .030), disinhibition (r = .351, p = .027) and executive dysfunction (r = .327, p = .042). This suggests that individuals with greater frontal lobe-related problems also tended to have poorer receptive language and a tendency to lose receptive language under stress.

Lastly, baseline receptive speech was correlated with Autism Internal Experience factor 1, with individuals with impaired receptive speech scoring higher (r = .311, p = .045). The impaired group scored an average of 17.75+/-3.105, with the unimpaired group scoring 13.09+/-6.147. High scorers on this factor were visuospatial thinkers who tended not to use internal language. This suggests a link between receptive language and verbal thinking, which has been suggested by previous studies as well. This study found that autistic individuals who scored better on nonverbal IQ than verbal IQ were less likely to use inner speech while solving math problems than autistics with other profiles.

It's interesting to speculate about the reasons for better and more consistent written than spoken language performance in my participants. This may reflect the written modality of the survey, meaning that individuals with impaired written language were less likely to complete my survey. Alternately, it could reflect better visual than auditory language abilities (particularly since AIE factor 1, reflecting visual thinking and lack of internal speech, was correlated with receptive spoken language impairment). It could also be due to greater processing time allowed by written communication. It would have been interesting to see if signing is easier than speech, but unfortunately extensive childhood exposure to sign language is not typical for most autistic adults. (Hearing autistic children of Deaf adults would be able to shed light on that question, but they're a minority within a minority.)

However, many studies into autistic children with complex communication needs have found that sign language can be useful for many children - this study successfully taught a few signs to autistic kids who had made little progress learning speech, this study found that more children acquired receptive signing than receptive speech from exposure to SimCom (simultaneous communication - speaking and signing the same words at the same time), and this study found that three minimally verbal autistic children readily learnt signs from key word signing but only two of them showed improvements in speech. Although these studies all used participants with much more severe language problems than my sample, this suggests that the better written than spoken performance in my sample may be due to the visual modality of communication.

In addition, receptive language problems appear to be more common in younger participants. This may suggest that these issues lessen with age, that certain ages have reporting biases, or that younger generations of autistic individuals are more likely to have receptive speech issues. Very few studies have assessed changes in language ability between adolescence and middle age in autism. The only study I could find reported no significant change in verbal IQ in a longitudinal sample assessed in adolescence and in adulthood, although both adolescent and adult scores were higher than childhood scores. Please note that it's unclear whether the mild language issues described by my participants would translate into lowered VIQ, especially since VIQ combines multiple areas of language into one score. In particular, in adolescents and adults, VIQ assesses both written and spoken language.

Women also had more severe receptive language problems than men, both in terms of baseline performance and variability. This runs counter to the general tendency for girls to be better at language than boys, however, other studies have also found autistic females tend to have more language problems than autistic males. Why this should be the case is unclear.

Variability in receptive language appears linked to frontal lobe issues. Anecdotally, sensory overload or disruptive sensory cues (such as background noise) were a common trigger for this variability - something that other studies have found as well.. The ability to screen out irrelevant stimuli is sometimes called 'sensory gating', and has been linked to the prefrontal cortex in both individuals with schizophrenia and people with brain injuries. In particular, the second study found that auditory distractions disproportionately affected the performance of patients with prefrontal brain lesions (as opposed to lesions in other regions) on an auditory matching task.

Although these language issues are mild compared to the issues experienced by some autistic individuals (such as individuals with complex communication needs), they were all significant enough to be noticed by the individual, and likely all caused some level of problems with communication on a regular basis. There is a stereotype that Asperger Syndrome causes no language problems, and high functioning autism causes language problems only in early childhood. However, even individuals who are not currently showing a noticeable language delay can have more subtle difficulties in language - difficulties which may be easily overlooked by others.

Further research should be done. This data suggests that many autistic adults may have better written than spoken language skills, subtle receptive and/or expressive language problems, and/or substantial situational variability in language functioning. These difficulties may be linked to frontal lobe issues, visual thinking and sensory processing issues.


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