Autistic Spectrum Disorders

Chapter 23
Autistic Spectrum Disorders

Zoe Connor


Autistic spectrum disorders (ASD) are common, comprising a range of complex and heterogeneous developmental disabilities that affect the way a person communicates and relates to people around them. Dietitians from all disciplines need an awareness of the challenges faced and posed by children with ASD. The typical characteristics of rigid thinking and resistance to change, combined with common sensory processing issues, make feeding problems, undereating and overeating common and traditional approaches to changing dietary behaviours are often inadequate.

Diagnosis and terminology

Diagnosis of ASD involves trained professionals marking a child (or adult) in three main areas of functioning, known as the ‘triad of impairments’:

  • social interaction (difficulty with social relationships, e.g. appearing aloof and indifferent to other people and difficulty with understanding others’ viewpoints and intentions)
  • social communication (difficulty with verbal and non verbal communication)
  • imagination (difficulty with interpersonal play and imagination, e.g. having a limited range of imaginative activities, possibly copied and pursued rigidly and repetitively)

For a diagnosis of ASD, there must be impairments in each of these three areas, i.e. functioning falls below a threshold at which it interferes with day to day living [1]. Diagnostic criteria are taken from either the international or US diagnostic manuals ICD-10 [1] or DSM-4 [2]. In addition to this triad, repetitive behaviour patterns and resistance to change in routine are often present.

ASD is an umbrella term for three diagnoses:

  • autism, also known as classic autism and Kanner’s autism
  • pervasive development disorder not otherwise specified (PDDNOS), sometimes known as atypical autism
  • Asperger’s syndrome

Two rarer diagnoses are sometimes included under the ASD umbrella, but are not covered specifically in this chapter:

The differentiation between autism, PDDNOS and Asperger’s syndrome depends on the number and distribution of impairments within the triad as specified by descriptors in the diagnostic manuals [1, 2]. As a crude generalisation children with Asperger’s have developed speech by the age of 3 years and are seen as the more able end of the spectrum; autism is often seen as the less able end of the spectrum; and PDDNOS falls in between the two. The National Institute for Health and Care Excellence (NICE) has published guidance on recognition, referral and diagnosis of ASD [3].

Fifty per cent of children with ASD have learning difficulties and 70% have psychiatric disorders [4] including depression, anxiety, attention deficit hyperactivity disorder (ADHD) and behavioural or conduct problems. Other common coexisting conditions are motor coordination problems and epilepsy. These often multiple conditions further impair social and psychological functioning and increase the need for medical and dietetic input.

Genetics, prevalence and causes

ASD was once thought of as an uncommon disorder, but prevalence is increasing and it now occurs in at least 1% of children in the UK [5–7]. Boys are affected four times more than girls [8]. The increase is partly but not wholly due to increased recognition. For the majority of cases of ASD, the cause is unknown and is likely to be varied and multifactorial; 10% have underlying medical causes including at least 60 different metabolic disorders, neurological disorders and complex chromosomal abnormalities [9]. Genetic studies have failed to find any single ‘autism gene’, but genes that are linked to higher risks of autism are being identified. For families with a child diagnosed with ASD, the likelihood of having another affected child is increased by five to ten times [10]. It is thought that for idiopathic cases of ASD there could be an inherited predisposition which is triggered by some as yet unidentified environmental factor such as an infection, immunological reaction or toxin during pregnancy or early life [11] or, indeed, maternal nutrition. A large US population based case control study found that women who reported not taking prenatal vitamins (containing folic acid) before and during the first month of pregnancy were twice as likely to have a child with ASD as women who did take supplements. The same study identified particular maternal gene variants which made the likelihood of having a child with ASD seven times as likely when not taking vitamins [12].

There is much research into the biochemistry of children with ASD in the hope it will give a clue as to cause, enabling better sub-typing and treatment. Published research reports low serum iron [13], zinc to copper ratios [14, 15], magnesium [16], calcium and vitamin D [17]; increased plasma vitamin B6 [18]; abnormal plasma essential fatty acids [19] and amino acids [20], markers of reduced sulphation capacity [21–23], urine peptides; increased urine homocysteine; various other abnormal vitamin, oxidative stress, energy transport, sulphation and detoxification markers [24–28]. The quality and size of these studies vary, the dietary intake of the subjects tested is rarely taken into account and the clinical relevance and robustness of some of the methodology and results are yet to be clarified.

Management of ASD

ASD is seen as a lifelong condition; however, 4%–40% of children lose their diagnosis as they get older [29–33]. Loss of diagnosis is more common for those more ‘mildly’ affected, or without other coexisting conditions. Whether these changes are due to some sort of ‘recovery’ or just a shifting of how much underlying ASD traits impede ‘normal’ life is not known.

Management, with specialised education and structured support, aims to help children maximise their skills and achieve their full potential as adults. Many individuals who were ‘disabled’ as children can get to the point where they will ‘function normally’ socially and find work, have a family and live independently.

Medical treatment is usually focused on managing common comorbidities such as ADHD, anxiety, sleep problems or epilepsy. Other treatments focus on the early implementation of education and behaviour interventions where these services are available, teaching the individual (or helping parents to teach the individual) appropriate responses to social situations they struggle with, and on developing communication.

Key strategies commonly advocated for individuals with ASD are

The National Autism Plan [34] recommends that all professionals working with children have training in ASD awareness and that additional training should be provided for all staff delivering specific ASD interventions. Desirable changes to dietetic consultations for children and young people with ASD are given in Table 23.1.

Table 23.1 Considerations for dietetic consultations


  • A quiet and not too brightly lit consultation room and equally appropriate waiting area
  • Child safe consultation areas
  • Minimising the occasions parents need to bring their child to clinic
  • Consideration of home or school visits instead of clinic attendance
Organising appointments

  • Appointments that start on time to reduce anxiety of waiting, e.g. by giving the first appointment of the day or clinic
  • Giving a clear explanation of what to expect, with visual cues when possible, e.g. the appointment letter including a picture of the clinic, clinic room and dietitian
  • Allowing extra time for an effective consultation

  • Use of clear, simple language with short sentences
  • Avoidance of idioms, irony, metaphors and words with double meanings
  • Avoiding use of body language, gestures or facial expressions without verbal instructions
  • Awareness that dietary instructions may be misinterpreted or taken literally, e.g. ‘avoid fatty foods’ without clarification of what this means could result in an able young person with ASD checking labels and refusing to eat anything with a fat content
  • When needing to give instructions, e.g. for weighing or measuring, do not assume that a non verbal patient cannot understand what is being said
  • Explain what you are going to do clearly before doing it and if possible show a picture or doll to explain what you are going to do, or demonstrate on a parent or yourself
  • Give direct, clear requests with as few words as possible, e.g. sit here, stand here
  • Awareness that a person with ASD may not make eye contact and may invade your personal space and climb over you; they may also use self-stimulating behaviour such as flapping their hands, making noises or putting their hands over their ears to relax themselves when overwhelmed by noises, lights, new surroundings or other non obvious stressors
Consider involving an education or speech and language specialist to aid more effective communication with the child

Nutritional management

Sensory processing difficulties

Impairment in perception of sensory stimuli is commonly reported in children and people with ASD. The reasons for this are not understood. Under-sensitivity in ASD may result in an increase in behaviours such as fidgeting, spinning, rocking or hand flapping which are forms of self-stimulation. Other children may demonstrate over-sensitivity by being aversive to touch, light and/or sound. Assessment of sensory issues and advice on management is best undertaken by an occupational therapist or other healthcare professional trained in sensory integration therapy (dietitians can access this training). Simple and practical help like wearing specially designed weighted clothing, having a discrete object to fiddle with, changing lighting, or reducing noise can sometimes have very significant effects on concentration and reduction in undesirable behaviours. Table 23.2 shows examples of sensory issues which could affect food intake and mealtimes.

Table 23.2 Examples of sensory issues that could affect food preferences and mealtime behaviour

Sense Hypersensitivity Hyposensitivity
Taste Strong preference for bland tasting foods
Aversion to spicy foods/many foods
Preference for strong tasting spicy foods
Licking objects
Smell Distracted or disturbed by food smells
Ability to detect smells that others may not, e.g. protein foods
Preference for strong smells
Visual Distracted by lighting, movement or colours at mealtimes
Preference for bland coloured foods
Preference for different foods to be presented separately
Disturbed by foods not presented in the usual way
Aversion to certain coloured foods
Auditory Dislike of crunchy foods
Distracted or disturbed by background sounds some of which may not be obvious, e.g. fluorescent light tubes
Preference for foods that make sounds when eaten, e.g. crunchy ones
Touch Dislike of mixed textures in mouth
Dislike of hot or cold foods and drinks
Dislike of some cutlery in mouth
Dislike of tooth brushing
Preference for lumpy or crunchy foods
Preference for very hot or very cold foods and drinks (possibility of burning self as hyposensitive to pain)
Tendency to frequently put foods and other objects to the mouth
Proprioception Alterations can contribute to clumsiness in eating or drinking or being distracted

by arm movements during eating
Vestibular attention Alterations can cause child to be distracted by moving or not moving self or

by body position during a meal

Selective eating

Children with ASD have been shown to have significantly more feeding problems (around 60%) than children without autism and they also eat a significantly narrower range of foods. This is not associated with the severity of ASD [35–38]. Commonly reported aspects of selective eating in ASD are

  • texture preferences/difficulty with transition to textured foods
  • food neophobia, i.e. significant distress at trying new foods
  • strong preference for foods of a particular colour
  • acceptance only of foods with familiar packaging
  • distress in some mealtime environments, e.g. it may be too noisy; too quiet; too bright; distressed by smells or look of other people’s food; distressed by being around other people
  • demands that food is presented in a consistent way, e.g. same plate and cutlery, positioning of food on plate
  • seeming not to recognise their own thirst or hunger

Nutritional assessment of a child with selective eating

As for any child with eating problems the assessment includes growth monitoring, assessment of nutritional adequacy of diet through diet history and recommendation of dietary changes to ensure adequacy, including supplements where needed. Additional areas to consider

  • underlying factors causing the selective eating
  • helping parents and other carers to understand the characteristic features of ASD that make selective eating more common
  • strategies to help change their child’s diet, both generic and specific for ASD
  • coordinating a multidisciplinary approach to changing the child’s dietary intake
  • requesting blood tests to check nutritional status

Continued refusal of family foods can cause great distress to families. Often one of the key things parents seek from a dietetic consultation is reassurance that their child is growing well and that their problem is not unique.

Risk of deficiencies

Children with ASD and selective eating are significantly more likely than typical controls to be at risk of at least one serious nutrient deficiency [39]. There are a number of case reports of severe nutritional deficiencies including scurvy presenting as muscle atrophy [40, 41], concurrent vitamin A and D deficiency presenting as a limp and periorbital swelling [42], three cases of vitamin B12 deficiency presenting as partially reversible optic neuropathy [43], three cases of vitamin A deficiency presenting as vision loss [44–46] and two cases of severe malnutrition, one involving a rash resolving with zinc supplementation [47].

Strategies for dealing with selective eating

Typically, parents with children with ASD and chronic selective eating will report that they have tried standard behavioural advice for toddlers with faddy eating and not found this to be helpful. Parents often need individualised advice to deal with the specific needs of their children or need intensive interventions such as those offered by multidisciplinary feeding clinics to see even small progressions with their child’s diet.

Parents find the following strategies useful.

Make mealtimes more predictable

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Apr 1, 2017 | Posted by in NUTRITION | Comments Off on Autistic Spectrum Disorders

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