High-Functioning Autism (HFA) is one of the autism spectrum disorders. In this situation, people with HFA have better cognitive performance than other autistic children, and mostly, their intelligence quotient (IQ) score is more than seventy. However, children with HFA have poorer communication and social skills compared to healthy children (
21,
22). Joint attention skills (JAT) are a significant deficiency in children with ASD, in addition to stereotyped behaviors or special interests and communication deficits that affect verbal and non-verbal strategies. Deficits in JAT are associated with poor attitudes about the mind, communication, and self-regulation (
23,
24). JAT is a condition in which two people actively focus on a thing, event, or situation. In normally developing children, JAT is often completed by the end of eighteen months (
24). According to the theory of Sigman and McGovern (2005), it is considered a critical deficit in children with ASD of any spectrum (
25,
26). Children with autism spectrum disorders have deficits in JAT, but their mechanisms are unclear. A hypothesized mechanism underlying the social disorders associated with HFA is a defect in the Mirror Neuron System (MNS) and has been proposed in the form of Broken Mirrors theory. Deficits in MNS activity may explain abnormal social skills common in ASD, such as impaired JAT, understanding others' goals, and empathy (
27,
28). This disorder likely stems from the inability to form and coordinate social representations of oneself and others.
Electroencephalogram (EEG) showed that MNS activity in children with ASD shows abnormalities compared to children with normal development (
29). However, few studies have focused on operationalizing such solutions to improve MNS defects potentially. Direct recording of neural activity using electromagnetic methods has shown activation patterns associated with mirror neurons (
30,
31).
In the first studies on the effect of NF on autism symptoms, Jansiewicz et al. (2006) evaluated the effectiveness of NF training on children with ASD. In the mentioned research, twenty-four 24 children with ASD were divided into two equal groups of 12 people regarding gender, age, and severity of the disorder. NF was taught to one group (experimental group), and this intervention was not performed for the other group (control group). The study showed that NF training caused a 26% reduction in autism symptoms compared to the control group (3% reduction) (
21). Scolnick (2005) reported that their EEG performance, concentration, and attention improved after 24 sessions of NF, and their anxiety and unpleasant social behaviors decreased (
32). Despite some conflicting results about the effect of NF on the performance of people with ASD, the results of Kouijzer et al. (2013) (
33), Coben et al. (2010) (
34), Thompson et al. (2010) (
35), showed that NF can help improve the performance of children with ASD through brain waves as a new treatment method based on conditioning and reinforcement. Accordingly, many parents and physicians are looking for low-risk and effective treatment methods such as NF to reduce the symptoms of ASD. Mohammadi et al. (2019) reported that the effectiveness of NF in improving cognitive and social skills in 7-12-year-old children with ASD was significant (P < 0.001) (
36). In addition, similar results by Carrick et al. (2018) concluded that the NF method affects the brain activities, motor sensors, and daily behavior of people with ASD (
37). However, the results of Marlats et al. (2019) showed that the effectiveness of NF on mild cognitive impairment in adults is not significant (
38). Although the studies of Carrick et al. (2018) and Marlats et al. (2019) were similar regarding subject matter and objectives, the difference in the results could be due to the difference in the population (
37,
38).
Regarding the effect of NF, there are disorders in the growth process of neuronal networks in the brains of children with ASD. Thus, structural or pathological changes are not seen in evaluating the brain tissue of these patients. NF can be an exercise to restore the neuronal network function of autistic patients (
39). The attitude towards the situation is that autistic children have an over-excited nervous system, which causes the child not to pay attention and perform properly. Therefore, the first step for improving the performance of autistic children is to remove their nervous system from the aforementioned critical state (
36). NF helps identify cognitive problems and improve cognitive processes in autistic children by improving self-regulation of the brain. In addition, NF leads to better cognitive performance by increasing beta waves and decreasing theta waves. On the other hand, increasing beta waves increases alertness, concentration, and metabolism, which can improve cognitive and social function (
40).
Activity of Daily Living (ADL) is one of the life dimensions of patients with ASD that can be affected due to the consequences of this disease. Orsmond et al. (2007) found that adolescents with more independence in ADL participate more in community and creative activities (
41). Mirzaie et al. (2018) showed that ADL provides opportunities to participate in two-person and group activities, especially in the early years of life. In addition, ADL affects the child's development and can affect the development of language, the creation of social skills, and the achievement of academic skills in the future (
42). According to the results of the studies mentioned above, it is logical that effective treatment methods on social skills also affect ADL activity. In general, NF can affect cognitive restructuring, muscle relaxation training, life skills training, and coping with anxiety-provoking situations. Mohammadi et al. (2019) concluded that NF has a significant effect on ADL improvement in autistic children (P < 0.001) (
36).
In addition to the positive and significant impact of NF on the social skills and cognitive performance of autistic patients, this treatment method improves other disorders and similar diseases, including children with attention-deficit/hyperactivity disorder, generalized anxiety disorder, multiple sclerosis, reading disorder, social cognitive deficits, and attention deficit hyperactivity disorder has a positive and significant effect (
43-
48). According to the results, NF therapy is an effective treatment method for mental disorders.