Simply because someone is diagnosed with one condition does not mean that he or she does not have other identifiable disorders. Autism is difficult enough, but when combined with depression the impact is greater still. Obviously, it is more challenging to detect or treat depression in people with communication difficulties.
Depression is considered to be more prevalent among people with autism than people in the general population[i] and in fact depression is thought to be the most common psychiatric illness of persons with autism. [ii]Whether that is more because of the stress of living with autism or a genetic predisposition towards depression is still hard to determine, but it has been demonstrated that, like most of us with depression, autistic individuals with depression are more likely to have depression in their families.[iii]
Circumstances which may contribute towards depression in people with autism include the knowledge that they are different from others, difficulties with social interaction, loneliness, feelings of failure, and extreme anxiety. Sexual frustration may also be a factor in teenagers and adults.[iv]
In addition to the usual symptoms of depression (e.g. sleep problems, increased or decreased appetite, tearfulness or social withdrawal), a person with autism may exhibit an increase in behaviors such as hand flapping, echolalia, or rocking, or displays of inappropriate emotions.[v] They may be more susceptible to catatonia, which typically is expressed as slower movement and a decrease in self-care, or show greater obsessive-compulsive behaviors. Increases in aggression may also be symptomatic of depression[vi] and so can a decrease in interest in usual preoccupations.[vii]
Depression is thought to be more likely with age, so during adolescence it may become more prevalent. In the case of persons with Asperger’s Syndrome or other high-functioning autism the change to high school or college may be a particularly stressful time when depression can appear.[viii]
Some evidence suggests that the higher functioning a person with autism is the greater the odds of being affected by depression, but this is still speculation at this point. It is known that higher functioning people with autism are more prone to low self-worth, which would fit with this theory.[ix]
As for treatment, “most studies advocate the use of a structured form of psychotherapy, along with appropriate behavioral and educational interventions. In more able and older persons with autism, cognitive-behavioral strategies may help to cope with anger and depression, although these are seldom successful in isolation.” While medication is increasingly being prescribed for the treatment of persons with both autism and depression, this appears to be as a result of the known benefits for others with depression rather than any research on their effect on people with autism in particular.
While treatment for depression is not intended to treat autistic symptoms, it is likely to provide a better quality of life for both the person with autism and depression and reduces the level of support required from the family and community.[x]