Co-Morbidity Between Intellectual Disability and Psychiatric Symptoms 7/25/23

The presence of Intellectual Disability (ID) increases the risk for co-occurring psychiatric disorders in child, adolescent, adult and geriatric patients. Behavioral and emotional problems are three times more likely to occur in these groups and they are frequently not recognized or appropriately treated. This said, problematic behaviors and emotions in this population may also be related to or impacted by other issues, such as undiagnosed medical and social problems, so careful assessment is quite important.

There has been a recent shift in the approach to patients with ID, with greater focus on adaptive functioning across domains, including cognitive, social and practical capacities, rather than based purely on an IQ score. Since ID can be caused by a variety of factors, including genetic, perinatal, environmental and other issues, it is thus important to assess the underlying etiology of the ID, because it can inform the assessment of problems symptoms and guide treatment efforts.

For a patient with Intellectual Disability exhibiting behavioral and emotional symptoms, it is important to conduct a focused medical review of systems as sometimes a patient “acts out” as a way to communicate physical discomfort (for example: from an infection or headache or abdominal issue). Other precipitants may include a behavioral profile to avoid non-preferred activities or as a protest to a change in routine—this particularly with persons who are non-verbal or verbally limited. Individuals with ID are at greater risk of trauma exposure and abuse, so assessment of these potential concerns should also be part of the evaluation protocol.

External considerations aside, co-occurring psychiatric conditions are not uncommon in the population and the most common psychiatric disorders that co-occur are Autism Spectrum Disorders (ASD), Mood Disorders (Anxiety and Depression) and Attention Deficit Hyperactivity Disorder (ADHD). Less frequently, ID patients may also present with co-occurring disorders including psychotic disorders and bipolar conditions which need therapeutic interventions comparable to that given to non-ID individuals.

It is important to ask the patient (if possible) and caregivers about current behavioral and emotional concerns, with attention to how appropriate the symptoms are given the patient’s developmental and functional capacities, and also, how the presenting symptoms are different from their baseline presentation. In this process, it is important to avoid misattributing symptoms to the patient’s ID when they may be a result of a co-morbid psychiatric condition. It can be helpful to use screening tools and use diagnostic criteria adapted for patients with ID conditions.
With respect to patients with co-occurring ID and ADHD, symptoms of hyperactivity tend to occur earlier in the patient’s life and symptoms of inattention tend to last longer into adolescence and young adulthood. It is of note that stimulant medications, which are the mainstay of treatment for ADHD in youth, are generally less effective in children with co-morbid ID and ADHD. This said, a stimulant trial in patients with co-morbid ADHD symptoms would generally be appropriate along with careful monitoring of side effects and efficacy. Non-stimulants such as the alpha agonists and atypical antipsychotics may be helpful for the young patients with ID and co-morbid disruptive behavioral disorders (including ADHD).

With respect to anxiety and depressive disorders in the ID patient, these individuals may struggle in identifying their feelings, and it can be challenging to assess whether a non-verbal or speech-limited individual’s behaviors is related to underlying anxiety or depression. Input from caregivers across multiple settings can help with this determination. The SSRIs can be useful in patients with ID and clinical depression and/or anxiety, again with close monitoring for side effects.

In summary, when seeing patients with Intellectual Disability, it is important to assess for co-morbid behavioral and emotional concerns and possible psychiatric disorders with full attention to their overall medical and their psychosocial status.

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