Behavioral characteristics in the triad of core symptoms

We reviewed what instruments were used to evaluate behavioral characteristics. Those that evaluated the BAP globally, that is, that included the three core domains of the syndrome, are shown in Table 2. In the 35 studies reviewed, only four instruments were used to evaluate the triad of core symptoms in parents: the Family History Interview (FHI),¹⁷ the Autism Spectrum Quotient (AQ),¹⁸ the Broader Phenotype Autism Symptom Scale (BPASS),¹⁹ and the Broad Autism Phenotype Questionnaire (BAPQ).⁸ FHI was the first instrument used for this purpose and was the most frequently used in studies up to 2000. Today, the questionnaire most often used in the AQ. Other instruments also evaluate isolated behavioral characteristics, and of the three domains, language is the one evaluated in most instruments.

The selected studies about behavioral characteristics of parents of individuals with autism are listed in Table 3.

Changes in social interaction

Seven articles evaluated social relationships of parents of individuals with autism.^{7 , 8 , 11 , 20 , 24 , 26 , 28} None of these studies evaluated only this domain, and social interaction was evaluated together with other behavioral characteristics. Moreover, social difficulties were approached according to different dimensions, and each study had a specific observation focus of the social functioning of parents of individuals with autism.

Some studies evaluated the interest of parents in social interactions,⁸ and others evaluated social skills.⁷ Results demonstrated that some individuals prefer not to interact and are aloof,⁸ whereas others do want to interact, but are not able to do it satisfactorily.

Losh et al.²⁸ found that 23% of the parents of multiple-incidence autism families do not have friends, in contrast with 11% of parents of single-incidence autism families and 3% of parents of children with Down syndrome. High rates of social difficulty in multiple-incidence autism families were also found in the studies conducted by Bernier et al.²⁴ and Piven et al.^{6 , 20} Moreover, parents of children with autism had limited friendships⁶ and often worked in fields that require little social understanding, such as math, engineering and physics.²⁶

Language and communication impairments

Sixteen studies evaluated the communicative characteristics of parents of individuals with autism.^{6 - 8 , 11 , 16 , 20 - 25 , 27 , 29 - 32} Seven studies evaluated this domain together with others (social domain and rigidity),^{6 - 8 , 11 , 20 , 22 , 24} and nine were specially designed to evaluate communicative skills.^{16 , 21 , 23 , 25 , 27 , 29 - 32} Seven evaluated structural language abnormalities^{21 , 22 , 27 , 29 - 32} and nine, the social use of language (pragmatic language)^{6 - 8 , 11 , 16 , 22 , 24 , 25 , 31}; some evaluated these two communicative characteristics. Although structural language abnormalities are not classified as behavioral characteristics, they were included in this section because they lead to communicative deficits.

In a pioneering study, Landa et al.²⁵ evaluated communication of parents and found three groups of pragmatic abnormalities measured by means of the Pragmatic Rating Scale (PRS): disinhibited social communication, awkward/inadequate expressions and odd verbal interactions. Since that study, pragmatic language skills have been broadly investigated, which corroborates the idea that parents of children with autism have social communication difficulties.^{6 - 8 , 11 , 16 , 24 , 27}

Abnormalities associated with structural language have also been evaluated in groups of parents. Whitehouse et al.²³ evaluated language deficits and found that parents of children with autism and parents of typically-developing children had similar performances, and that both groups had a better performance than that of parents of children with specific language impairments (SLI). Therefore, the difficulties associated with structural language are not found in the BAP of parents. This finding has been confirmed by the studies conducted by Bishop et al.,³² Whitehouse et al.,³¹ and Lindgren et al.³⁰ However, other studies have found phonological processing deficits among parents of individuals with autism, which supports the hypothesis that these deficits are part of the BAP.²⁹

The analysis of reading and writing acquisition revealed that the difficulties of some parents of children with autism seem to be associated with an abnormal development of language rather than with autism.²¹ In the study conducted by Folstein et al. in 1999,²² only the parents with a history of cognitive deficits associated with language in childhood had a poorer performance in reading and writing tasks than parents of individuals with Down syndrome. A history of language delays and deficits in childhood in the group of individuals with autism was also reported by Piven et al.²⁰

Pragmatic language deficits may be seen as a reliable characteristic of the BAP. However, other language deficits, such as delays and difficulties in reading and writing acquisition and difficulties in structural language use, although present in some of the parents of children with autism, have not been confirmed to be part of the BAP,^{23 , 30 , 31} and further studies should be conducted to investigate this topic.

Restricted interests and repetitive and stereotyped behavior

Of the three core symptoms of autism, this is the one with the smallest number of studies that evaluated parents. Only five studies were retrieved.^{6 , 8 , 20 , 24 , 28} Moreover, this domain has only one category, divided into different characteristics: intense restricted interests; adherence to routines and rituals; stereotyped and repetitive motor mannerisms; and persistent preoccupation with parts of objects.¹ Although it is a single category, the behaviors described here are substantially heterogeneous, but the main studies using questionnaires to detect BAP characteristics in parents have not defined this subdomain classification.

In the studies conducted by Piven et al.,⁶ Hurley et al.,⁸ and Losh et al.,²⁸ rigidity describes resistance to changes and a strong attachment to routines. Bernier et al.²⁴ evaluated behavioral flexibility and range of interests. Piven et al.,²⁰ in turn, evaluated restricted interests and rigidity, or perfectionism. No study included stereotyped and repetitive motor mannerisms in the evaluation of parents. Questionnaires evaluated the same domain in different ways.

The hypothesis that parents also have a rigid personality, with little interest in what is new, as well as with difficulties in dealing with routine changes, has been confirmed in some studies.^{6 , 8} In the study conducted by Bernier et al.²⁴ only parents of multiple-incidence autism families had characteristics of rigidity. Losh et al.,²⁸ however, found that parents of multiple-incidence autism families had more characteristics of rigidity than parents that had only one child with autism, who, in turn, had more autism traits than parents in the control group.

Cognitive models

Eighteen studies evaluated central coherence, executive functions and ToM in groups of parents of individuals with autism, and most included more than one cognitive model. Table 4 describes these studies.

Central coherence

The theory that individuals with autism have a weak central coherence, developed by Frith in 1989,⁴⁹ suggests that most people that do not have autism-spectrum disorder have a natural and spontaneous tendency to integrate details into a global entity and to process information received according to its context, observing and recalling more of the general picture than of the details. In contrast, people with autism-spectrum disorder seem to have a deficit in local processing and often miss the general meaning. However, different from other cognitive theories, the theory of a weak central coherence does not define deficits; rather, it claims that strong and weak central coherence have advantages and disadvantages and are merely different cognitive styles.⁵⁰ Initially, this theory attempted to explain all the core symptoms of autism. However, after several studies that supported, or not, this hypothesis, it is currently seen as one of the cognitive styles found in the disorder, which contributes, therefore, to the view that autism includes multiple deficits.¹⁵

In addition to visual and spatial skills, the central coherence cognitive models also include verbal skills. Individuals with a weak central coherence have more difficulties in understanding words by means of their context, which, therefore, contributes to a deficit in communication.⁵¹ Some studies found abnormalities in central coherence tests only when evaluating verbal skills and not, therefore, in tests of visual skills.⁴⁶

The theory of a weak central coherence, although logical and convincing, remains inconsistent in the case of parents of individuals with autism. Six studies evaluated this cognitive model,^{10 , 36 , 38 , 39 , 45 , 46} but only two evaluated verbal characteristics.^{36 , 46} Results have been inconclusive, as authors constantly apply the same instruments to different samples and find different results.^{36 , 45} Bölte & Poustka³⁸ evaluated central coherence skills of parents of children with autism and found a better performance in the Embedded Figures test, but not in the block design test. They found that the improved skill of people with autism to identify simple forms embedded in complex figures seems to be the main characteristic of local processing. Therefore, they suggest that this skill may be a characteristic of the BAP. Jonge et al.³⁹ found that fathers performed better than control parents only in number of attempts to find the correct answer in the Embedded Figures test. However, the same authors conducted a study to evaluate central coherence of parents using the block design test and did not find differences between groups.⁴⁵

Happé et al.³⁶ evaluated parents of children with autism using a battery of tasks and found that fathers had a weak central coherence according to visual and verbal tasks. However, in the same study, mothers had abnormal results only in verbal tasks. Their findings of unequal results for different sexes are inconclusive, according to the authors, because of the small sample size.

Other studies did not find any differences between parents of individuals with autism and other groups of parents, and their authors suggest that parents of individuals with autism have deficits in local processing, or a weak central coherence.^{10 , 45} However, their studies included only tests that evaluated visual skills. Losh et al.⁴⁶ also did not find any differences in visual skills between groups of parents, but difference were detected in verbal skills.

Executive functions

Executive functions are a set of integrated skills that allow individuals to direct their behavior to goals, to monitor efficiency and adequacy of these behaviors, to drop inefficient strategies and, therefore, to solve immediate, medium-term and long-term problems.⁵² Individuals with autism have deficits in these cognitive skills, which may be responsible for a high level of rigidity and perseveration,⁵³ as well as for the performance of rituals and difficulties in dealing with changes in their routines. According to the seven studies retrieved,^{33 - 35 , 41 , 42 , 44 , 46} parents of individuals with autism also have deficits in executive functions, particularly those associated with planning^{34 , 35 , 42} (however, see Wong et al.⁴¹ and Losh et al.⁴⁶); difficulties in operational memory⁴⁴ (however, see Wong et al.⁴¹); cognitive flexibility³⁵ (however, see Bishop et al.,³³ Delorme et al.,⁴² Losh et al.⁴⁶); and verbal and non-verbal fluency⁴¹ (however, see Delorme et al.⁴²).

Although several studies confirm the presence of deficits in executive functions of parents of individuals with autism and their children, these deficits are not associated only with this disorder,⁵³ which raises questions about what role they may have in explaining the behavioral abnormalities found in autism.

Theory of Mind

Theory of Mind (ToM) is the main cognitive model of the social impairments of individuals with autism-spectrum disorder. Defined as the capacity to impute states of mind to oneself and others,⁵⁴ individuals with a ToM deficit may have serious deficits in their interpersonal relationships, as the understanding of the mental state of others may guide one's own behavioral and emotional responses. In addition to social interactions, ToM deficits may lead to pragmatic language impairments, absence of pretend play and lack of empathy.¹⁴

ToM may be divided into two domains: decoding mental state, which involves the capacity to perceive the mental state of others in observable information, such as facial expression and gestures; and reasoning other's mental states, which involves the capacity to integrate information in the context with information about the history of people (attitudes, knowledge, experiences) to understand their behavior.⁵⁵

Eight studies evaluated ToM in parents of individuals with autism.^{16 , 37 , 40 , 43 , 44 , 46 - 48} In the analysis of decoding tasks, parents of individuals with autism had more difficulties in reasoning the emotions of others' than parents in the control group in the studies conducted by Palermo et al.⁴⁰ (sadness and disgust), Wallace et al.⁴⁷ (fear and disgust) and Neves et al.⁴⁸ (fear, anger and happiness). However, results were similar to those found for the control groups in the studies conducted by Gokcen et al.⁴⁴ and Bölte & Poustka.³⁷ In the analysis of mental state reasoning tasks, parents of individuals with autism performed worse than the control group in the study conducted by Di Michele et al.¹⁶ and Gokcen et al.⁴⁴ The instruments used in the evaluations were not the same.

Some studies evaluated parents of individuals with autism using behavioral and cognitive measures. Parents that had abnormal results in a behavioral domain (social interest) had a poorer performance in the ToM tests than parents of individuals with autism who had abnormal results in other behavioral domains, such as rigidity and language pragmatics, and parents of typically-developing children.^{43 , 46}