Clinical features

Autistic spectrum disorder is usually diagnosed in childhood; but some people with high functioning autism (Asperger syndrome) may not receive a formal diagnosis until adulthood.

70% of people with autistic spectrum disorder have an IQ of 70 or below. Average IQ is 100 and an IQ of 70 or over is considered to be normal, hence a significant number of people with autistic spectrum disorder are classified as having learning disabilities. However evaluation of IQ in isolation does not predict how an individual will function on a day to day basis. There is much variation in the type and range of functional restrictions shown by people with autistic spectrum disorder.

The following spectrum of features and functional limitations may be seen in adults with autistic spectrum disorder. The severity of the disabling effects is linked to the degree of co-existing learning difficulties/disabilities:

• May have no speech or very limited vocabulary, echo speech of others
• May not understand language, use of emphasis or tone variation to convey meaning
• May have difficulty in using or understanding non verbal means of communication e.g. eye contact, facial expressions, body language, gestures
• May not understand similes, metaphors, humorous, ironic or sarcastic remarks
• May have difficulties in planning and organizing activities
• May be unable to predict outcomes and the consequences of actions
• May have little or no imagination
• May confuse reality with fantasy
• May be unable to appreciate thoughts, feelings, and emotional distress in others
• May have limited or no insight into their condition
• May indulge in repetitive and stereotypical behaviour e.g. tapping objects, watching objects spin, rocking, teeth grinding
• May maintain rigid and inflexible routines e.g. eating the same food every day, watching the same videos
• May exhibit difficult, bizarre or challenging behaviour if routine is changed, or sometimes unpredictably.
• May repeat the same comments or ask the same question many times
• May be uncooperative in carrying out personal care or allowing another to help.

Some individuals with autism are reported to have difficulties in interpreting and reacting to sensory information. For example they may find loud noises very disturbing; they may have abnormal reaction to taste such that they eat soil or dirt; they may perceive touch in a different way such that the texture of certain clothes material may be distasteful to them.

Adults with high functioning autism (Asperger syndrome) usually have normal cognitive function with minimal intellectual impairment, and may be educated to a high degree. The features listed above describe a spectrum of difficulties that may be present in people with high functioning autism to varying degrees, but they all have difficulties with social interaction and a tendency to engage in restrictive interests and rituals. For example they may speak at length using unusual and sophisticated vocabulary, but in a monotonous tone or unconventional way. They may make socially inappropriate comments or find it difficult to maintain a conversation with other people or interact with a group of people. They have difficulty in understanding other peoples’ perspective or feelings. Their intense interest in something else may hamper their ability to talk to others or to engage in other activities.

Adults with autistic spectrum disorder may develop mental health conditions such as depression, anxiety, compulsive behaviour, tics etc. In some individuals symptoms of anxiety may lead to additional problems in carrying out daily living tasks, communicating and engaging in social interactions (see Anxiety Disorders guidance and Depressive Illness guidance). Both diagnosis and treatment of conditions such as depression/anxiety can be difficult in those with communication problems. Adolescents and young adults with Asperger syndrome have a higher suicide rate than those of the same age group in the general population.

Amended April 2008