The target population consisted of children attending a specialist school for individuals with ASD, children who were on the waiting list for a place at that school, and patients attending selected private specialist clinics. The parents of the children enrolled at the school were personally invited to participate in the study, while those whose name was on the waiting list were invited by telephone. The parents identified at the private clinics selected for the study were invited to participate in person by the attending psychiatrist/neurologist. Any parents who refused to participate in the study, adoptive parents and those who answered the questionnaires inappropriately were excluded from the study. The final sample consisted of 161 children, 161 mothers and 108 fathers. The data were collected between April 2014 and April 2016. The internal review board of the BAHIANA School of Medicine and Public Health approved the study protocol on March 12, 2014 under reference 551.381.

Psychiatrists and a pediatric neurologist with extensive experience in the diagnosis and treatment of disorders of neurodevelopment evaluated the children. To increase the reliability of the diagnoses, the study coordinator personally trained all the professionals involved in the study. The children’s diagnoses were made in accordance with the criteria established in the Diagnostic and Statistical Manual of Mental Disorders - DSM5 (APA, 2013), with the Childhood Autism Rating Scale (CARS) being applied to provide a better characterization of the symptoms of ASD in the patients. CARS is an observational scale that can be used for children of two years of age or more. A trained observer evaluates the child’s behavior in 15 domains affected by autism and attributes scores ranging from 1 to 4 for each item, with higher scores reflecting more inappropriate behavior (Schopler, Reichler, & Renner, 1988). The factorial personality inventory (FPI) was the instrument used to evaluate personality traits in the parents. This consists of a self-report, structured questionnaire that is based on an adaptation of a modified version of the Edwards Personal Preference Schedule (EPPS) (Araújo, 2008). This tool was elaborated and validated in Brazil with 3,399 subjects (33% men and 67% women), the majority (49.5%) consisting of university students from 11 states in Brazil (Pasquali, Azevedo, & Ghesti, 1997). The test consists of the evaluation of 15 personality traits, with each trait being evaluated through nine items. Possible responses range from 1 to 7, with 1 indicating that the item is considered “not at all characteristic” and 7 “completely characteristic”. The result for each trait is divided into percentiles in accordance with the scores, with high, moderate and low scores corresponding, respectively, to ≥ 70^th percentile, between the 69^th and 31^st percentiles and ≤ the 30^th percentile. The 15 traits measured in the inventory are: Nurturance expresses desires and feelings of kindliness, compassion and tenderness in which the subject wishes to be sympathetic to and fulfill the requirements of someone in need; intraception describes individuals who are dominated by a search for happiness, by fantasy and by imagination; succorance represents a search for support and protection; deference is related to respect, admiration and reverence to others; affiliation signifies giving and receiving affection from friends; dominance refers to feelings of self-confidence and the desire to control others; abasement is the tendency to submit passively to an external force, to be resigned to fate; achievement refers to ambition and endeavor, the desire to do something difficult; exhibition refers to vanity, to the desire to impress, to be heard and to be seen; aggression reflects anger and hate, individuals that like to fight, argue and attack; order represents a tendency to keep things clean, organized, balanced and precise; endurance expresses the ability to continue to perform a task that has been started no matter how difficult it may seem; change reflects the enjoyment of new things, not fearing things outside the individual’s normal routine; autonomy is independence, acting freely according to the individual’s own impulses; and heterosexuality refers to the desire to have relationships, including romantic and sexual relationships, with individuals of the opposite sex (Pasquali et al., 1997). The trait heterosexuality was not taken into consideration in the analysis, since it was deemed inappropriate in the validation studies and removed from the subsequent version of the inventory (Araújo, 2008).

The data collected using the evaluation instruments were entered into the SPSS statistical software package, version 22 and analyzed by descriptive and inferential analyses. For the analysis of the factorial personality inventory (FPI), the overall scores for each personality trait were added together. In the inferential analysis, bivariate Spearman’s correlation was used to identify positive or negative correlations between the scores for the personality traits in the parents, based on the FPI, and the scores for the symptoms of the children diagnosed with ASD, as according to the CARS. In the CARS, the higher the score given by the evaluating physician, the higher the symptom score. In the FPI, the higher the score, the greater the expression of the personality trait reported by the parents.

As shown in Table 1, a positive and statistically significant correlation was found between endurance as a personality trait in the mother and the symptom imitation in the child (r = 0.189*). A negative and statistically significant association was found between the personality trait succorance in the mother and the symptom adaptation to change in the child (r = -0.184*), the personality trait exhibition in the mother and the overall ASD severity in the child (r = -0.179*) and the personality trait aggression in the mother and the symptom verbal communication in the child (r = -0.192*).

Table 1

CARS/FPI	Nur	I	Succ	Def	Affl	Dom	Ab	Ach	Ex	Agg	O	End	M	Aut	Het
Item 1 - Interpersonal relationship	-.028	-.008	-.020	.013	.047	-.056	-.159	-.019	-.061	-.079	-.029	.121	-.058	-.011	-.259**
Item 2 - Imitation	.032	.103	.098	.144	.101	.002	-.044	.024	.000	-.082	.043	.189*	.091	-.056	-.116
Item 3 - Emotional response	-.133	-.093	-.160	-.014	-.097	-.128	-.102	.001	.022	-.103	.064	.004	-.106	-.090	-.214*
Item 4 - Body use	-.007	.100	-.153	.012	.027	-.086	-.029	-.014	-.042	-.153	-.007	-.037	-.031	-.085	-.123
Item 5 - Use of objects	.011	.081	-.054	.052	.020	-.070	-.074	-.025	-.142	-.167	.078	.055	-.036	-.008	-.138
Item 6 - Adaptation to change	.046	.008	-.184*	.061	-.021	-.119	-.043	.000	-.061	-.150	.130	.024	-.032	-.005	-.196*
Item 7 - Visual response	.060	.018	.050	.005	.048	.051	-.103	.019	-.080	-.085	-.001	.120	.031	.026	-.111
Item 8 - Auditory response	-.001	-.043	-.064	-.013	.036	-.052	-.094	-.068	-.116	-.142	-.014	.048	-.060	-.063	-.179
Item 9 - Taste, smell and touch	.069	.168	-.037	.039	.098	-.109	.057	.016	-.008	.040	.036	.067	-.057	.129	-.166
Item 10 - Fear or nervousness	.058	-.108	-.163	-.026	.008	-.136	-.029	.047	-.061	-.144	-.028	.058	-.022	-.009	-.218*
Item 11 - Verbal communication	.041	.047	.029	.093	.099	-.120	-.087	-.079	-.143	-.192*	.050	.123	.038	-.018	-.180
Item 12 - Non-verbal communication	-.049	-.079	.101	.029	-.016	.022	-.082	-.096	-.096	-.077	-.047	.030	.011	-.042	-.131
Item 13 - Level of activity	-.009	-.055	-.105	.066	.086	-.086	.022	.001	-.017	-.004	.003	.046	-.025	-.072	-.043
Item 14 - Intellectual response	-.007	-.108	.035	.071	.054	.071	-.053	-.009	.030	-.068	.070	-.017	-.003	.004	-.001
Item 15 - General impressions	-.019	-.062	-.104	-.019	-.035	-.167	-.164	-.062	-.179*	-.161	.057	.114	-0.52	-.058	-.269**
CARS Total	.002	-.026	-.079	.034	.045	-.111	-.106	-.039	-.128	-.164	.028	.072	-.022	-.043	-.228*

Nurturance (Nur), dominance (Dom), order (O), abasement (Ab), intraception (I), achievement (Ach), exhibition (Ex), heterosexuality (Het), affiliation (Affl), change (C), endurance (End), aggression (Agg), deference (Def), autonomy (Aut) and succorance (Succ).

As shown in Table 2, a negative correlation was found between the personality trait change in the fathers and the symptoms interpersonal relationship (r = -0.246*), imitation (r = -0.242*), inappropriate use of objects (r = -0.248*) and the overall ASD severity in the children (r = -0.217*). There was a negative correlation between the personality trait achievement in the fathers and the symptoms inappropriate use of objects (r = -0.231*) and sensorial symptoms in the children (r = -0.228*). A negative correlation was found between the personality trait affiliation in the fathers and the symptom adaptation to change in the children (r = -0.273*). There was a positive correlation between the personality trait aggression in the fathers and the symptom hyperactivity in the children (r = 0.232*) and between the personality trait succorance in the fathers and the symptom body use in the children (r = 0.256*).

Table 2

CARS/IFP	Nur	I	Succ	Def	Affl	Dom	Ab	Ach	Ex	Agg	O	End	M	Aut	Het
Item 1 - Interpersonal relationship	-.039	-.127	.092	-.088	.042	.044	-.136	-.150	-.049	-.005	.062	.021	-.246*	.023	-.147
Item 2 - Imitation	.089	-.021	-.007	-.079	.062	-.055	-.061	-.038	-.102	-.079	.091	.072	-.242*	.070	-.179
Item 3 - Emotional response	-.020	-.026	.200	.010	-.028	.125	.163	.011	.045	.087	.169	.072	-.007	.127	-.120
Item 4 - Body use	.192	.047	.256*	.002	.110	-.019	.078	-.039	.180	.043	.087	-.032	-.071	.101	.061
Item 5 - Use of objects	-.110	-.106	.075	-.182	-.107	-.048	.063	-.231*	-.115	.056	-.083	-.027	-.248*	-.077	-.123
Item 6 - Adaptation to change	-.141	-.103	.058	-.216	-.273*	-.100	.091	-.118	-.056	-.078	-.020	-.037	-.153	-.028	-.163
Item 7 - Visual response	.150	.061	.184	.061	.120	.114	.002	.147	-.040	-.003	.169	.012	-.067	.063	.053
Item 8 - Auditory response	-.040	-.096	.012	-.199	-.086	-.019	-.192	.043	-.086	-.100	-.034	.023	-.101	-.003	-.008
Item 9 - Taste, smell and touch	.087	-.061	.012	-.114	.069	-.153	.128	-.228*	-.044	-.014	.020	-.011	-.100	-.091	-.104
Item 10 - Fear or nervousness	.010	.029	.081	-.045	.011	-.011	.001	.047	.077	.071	.020	-.059	.004	-.027	-.022
Item 11 - Verbal communication	.105	-.006	.107	-.013	.078	-.024	-.126	-.097	-.085	-.083	.050	.109	-.230*	-.013	-.070
Item 12 - Non-verbal communication	.072	-.085	.104	-.138	.116	.030	-.161	-.086	-.084	-.040	.045	-.006	-.073	.003	-.095
Item 13 - Level of activity	-.010	.158	.018	-.006	.084	.001	.200	.011	.069	.232*	.088	.086	-.008	.112	-.024
Item 14 - Intellectual response	.129	.151	.204	.046	.186	.071	.082	.206	.203	.038	.166	.139	.022	.066	.046
Item 15 - General impressions	.008	-.067	.191	-.091	.126	.064	-.104	-.020	.061	.039	.125	.112	-.217*	.082	-.125
CARS Total	.066	.012	.191	-.108	.073	.038	.032	-.054	.006	.059	.123	.082	-.163	.050	-.090

Nurturance (Nur), dominance (Dom), order (O), abasement (Ab), intraception (I), achievement (Ach), exhibition (Ex), heterosexuality (Het), affiliation (Affl), change (C), endurance (End), aggression (Agg), deference (Def), autonomy (Aut) and succorance (Succ).

Some of the personality traits in the parents, evaluated using the FPI, correlated significantly with symptoms of autism in the children, while others did not. For the mothers, there was a statistically significant and positive correlation between the personality trait endurance and the symptom difficulty with imitation in the children. Endurance is a personality trait that may be associated with perseverance and rigidity, thus revealing a trait associated with rigid behavior in the broader autism phenotype in the mothers. A greater prevalence of limited interests, more rigid personalities, perfectionism and little interest in new situations have already been described in the parents of children with ASD (Murphy et al., 2000). The new finding the present study brings to light is the positive correlation between children with ASD who are less able to imitate and mothers who are more persistent. This result may indicate a genetic approximation between endurance/rigidity in the mothers and the children’s difficulty in imitating behaviors or learning by imitation, that is related with poor social ability (de Guzman, Bird, Banissy, & Catmur, 2016; Santiesteban et al., 2012).A negative correlation was found between some of the personality traits in the mothers and symptoms in the children: succorance and adaptation to changes; exhibition and the overall severity of ASD; aggression and verbal communication. Succorance and exhibition are personality traits related to sociability. Succorance refers to an active search for help and protection in another person, while exhibition refers to the desire to be seen socially. Other studies have reported altered social behavior in the parents of individuals with ASD (Yucel et al., 2014), as well as affective distancing and less reciprocity in friendships (Bolton et al., 1994; Piven & Folstein, 1994; Piven et al., 1997). The novel finding in the present study refers to a possible genetic correlation between poor sociability in the mothers (lower score of succorance and lower score of exhibition) and less adaptations to changes in the child, wish is related to rigid behavior. The negative correlation between Aggression in the mothers and verbal communication in the children indicates that a low level of Aggression in the mothers is associated with worst linguistic development in the children, which is an unexpected finding. None of the nine items of the factorial personality inventory (FPI) included under the domain aggression refers to aggression against individuals, but rather to aggression in an attitude of verbal confrontation (I am not afraid to tell people that I don’t like them; I like to confront points of view that oppose mine; I like to make fun of people who do things I consider stupid; I want to get my own back when someone insults me; I feel like telling people to shut up when I disagree with them; sometimes I get so irritated that I feel like throwing things and breaking them; I blame others when things go wrong for me; I’m not afraid to criticize someone in public when they deserve it; I like to read or watch news items about murders and other forms of violence). In this respect, in the FPI, low score of aggression in mothers reveals individuals who tend to be less verbally confrontational, and less verbal skilled correlates with children with worst verbal communication skills. To the best of our knowledge, there are no other references in the literature reporting this association.

Figure 1

A poorer expression of the trait change in the fathers, a proxy of rigidity, was correlated with child’s worst sociability (symptoms of worst interpersonal relationship), poor social ability (symptoms difficulty with imitation), repetitive behavior (symptoms of inappropriate and stereotyped use of objects), and greater overall severity of ASD. Previous studies have also shown that the fathers of individuals with ASD tend to have problems with change, an indication of the broader autism phenotype in the fathers (Bishop et al., 2004; Ruta, Mazzone, Mazzone, Wheelwright, & Baron-Cohen, 2012; Wheelwright, Auyeung, Allison, & Baron-Cohen, 2010). The finding in the present study refers to a possible genetic correlation between rigidity/inability to change in the fathers (lower score of change) and worst sociability, and repetitive behavior in the child.

The correlation between a poor expression of achievement, a proxy of difficulty with socialization and social adaptation, and the inappropriate use of objects (related to repetitive behavior) and sensorial symptoms in the children may also point to a genetic association between these traits. The negative correlation between the personality trait affiliation, a proxy of difficulty with socialization, in the parents and adaptation to changes in the children suggests a genetic association between poorer social skills in the parents and greater rigidity in the children with ASD. These correlations may indicate the presence of traits associated with the broader autism phenotype in the parents, which is in agreement with other references in the literature (Kose et al, 2013).

The present study suggests that rigidity (low expression of the trait Change) in the fathers was associated with a greater severity of symptoms regarding sociability, repetitive behavior and the severity of the overall symptoms of ASD in the child, thus indicating rigidity (difficulty with Change) as a possible endophenotype of ASD in the fathers. Other authors have discussed the hypothesis that parents of individuals with ASD also have a rigid personality, with little interest in new situations and difficulties in dealing with routine changes (Bernier, Gerdts, Munson, Dawson, & Estes, 2012; Hurley, Losh, Parlier, Reznick, & Piven, 2007). Poor sociability in the parents is related with repetitive behavior, sensorial symptoms and rigidity in the child. Sung et al. (2005) also found that traits of sociability and rigidity in the parents are indicative of greater heritability in relation to ASD, with a greater genetic correlation compared to traits such as expressiveness in social communication, communicative skills and the start of verbal communication.

Figure 2

In summary, both for the mothers and for the fathers, personality traits associated with greater rigidity and less flexibility, and personality traits associated with fewer social skills, corresponding to symptoms of the broader autism phenotype, were the traits that correlated more closely with the more severe symptoms of autism in the children.