Overview 

As of 2020, there are around 1.3 million people with an intellectual disability (ID) in the UK.¹ This often stigmatised condition is seeing light to new ways of management using pharmacological and psychological interventions. The aim of these is to improve symptoms of the condition and allow those with severe forms of ID to live independently. It is important to enhance the quality of life for these individuals by improving their social and personal skills, as well as supporting their family members and caregivers.

Read on to learn more about types of intellectual disability, symptoms and current medical intervention strategies. 

Introduction 

What is intellectual disability?

Intellectual disability (ID) is a neurodevelopmental condition which develops during childhood, usually before 18 years of age. More commonly referred to as a learning disability, the condition affects mental ability, learning and everyday life skills. 

As a child is growing and developing, signs of ID manifest early and some of the symptoms can be sitting up or walking late, difficulty in remembering, trouble speaking or beginning to speak later than other children.² In adolescence, these signs may manifest into issues with cognitive and adaptive functioning. Cognitive problems refer to having lower intelligence, often identified by a lower IQ score of 70-75 compared to the average score of 100, which leads to impaired problem-solving and judgmental skills.³

Adaptive functioning refers to conceptual, social and practical skill domains. A deficit in conceptual skills means the person will have trouble with reading, writing time and money, and social skills, which means the person may struggle with communication, empathy, and relating to their peers. Practical skills are ones which arguably affect those with ID most as they can struggle with activities of personal care and daily living like dressing and mobility, and also having the ability to travel alone and stay safe. This can make those affected feel very vulnerable and dependent on their carers, which can have a negative effect on their mental well-being. 

Nevertheless, the condition is broad and affects people differently, varying in symptom severity from autism spectrum disorder to Down’s syndrome. A lot of people with learning disabilities are still able to work, form friendships and relationships, and live independently.

Types of intellectual disability

Down’s syndrome

Down's syndrome is the most common genetic cause of intellectual disability in all those diagnosed with the condition, often at a mild to moderate level. For every 1000 babies born in the UK, 1 will have Down’s syndrome, and this condition accounts for 15-20% of the intellectually disabled population.⁴ Although it is a genetic disorder, it does not run in families so anyone could have a baby with Down’s syndrome. Some people with Down’s syndrome are healthy, yet others may have significant health problems like heart defects. As most children with Down’s syndrome will have intellectual disabilities and cognitive impairment, this means their language is often delayed and short and long-term memory is also affected. This can make it difficult for people with Down’s syndrome to interact socially and verbally express themselves to others. 

Autism

Once seen as medically synonymous conditions, autism spectrum disorder (ASD) and ID are now distinguishable disorders; however, the two can occur together. 

Autism is characterised more by a difficulty in social functioning than cognitive skills as the intelligence of autistic people is often within normal ranges. Previous research found that 23% of people with ASD have an IQ of less than the average of 85, while 45% have an average IQ score, and 32% had above average IQ scores.⁵

This being said, ASD is a spectrum, and the symptoms of those affected can vary. People with autism often find it hard to communicate with people and show empathy. They can also become sensory overstimulated, which means things like bright lights or loud noises can be overwhelming and make them feel stressed and anxious. They often relieve this stress by performing repetitive behaviour such as hand flapping or rocking themselves for comfort.⁶ 

ADHD 

ADHD (attention deficit hyperactivity disorder) is commonly diagnosed alongside ID. People with ADHD may seem restless and have trouble concentrating, which can affect their work ethic, concentration, organisation and ability to follow instructions. This can result in a deficit in intellectual development as children may be disruptive and perform poorly on tests. On the other hand, another main symptom of ADHD is hyperactivity, and if a child becomes hyperfocused on certain tasks, it may lead to no suspicions of intellectual challenges.

Intellectual disability and ADHD are often not diagnosed separately when co-occurring together and, therefore do not receive the treatment and support required.⁷

What causes intellectual disability?

The cause of ID is not always straightforward or known and can be due to a variety of factors which affect brain development either before/during birth or during childhood. 

Some common causes include:

Prenatal (before birth) causes

• Genetics, for example Down’s syndrome
• Teratogens (use of alcohol, tobacco, medications and radiation exposure) for example, foetal alcohol syndrome
• Infection, for example rubella

During birth

• Lack of oxygen to the baby’s brain (hypoxia)
• Premature birth
• Brain injury

During childhood

• Infection, e.g. measles or meningitis
• Serious head injury 
• Tumours/growths in the brain
• Medical conditions causing brain damage e.g. epilepsy

Medical interventions 

Many people do not regard intellectual disabilities as medical disorders needing intervention; however, for those with severe types of ID intervention can aid in improving independence and well-being. Furthermore, there is an issue with overprescribing medication to those with ID as it is quick. However, this further implies that this is a condition that must be ‘fixed’ when there is no cure. ID is a life-long condition so early and continuous treatment is needed for the best improvement in functioning. 

Pharmacotherapy 

The medications prescribed for those with ID are not specific to the disorder but aim to target conditions co-occurring alongside ID such as anxiety, depression, epilepsy and cerebral palsy.

Psychotropic medications such as antipsychotics, antidepressants and mood stabilisers are widely prescribed, often with the use of medication for physical problems.⁸ Although psychotropic medication can alter problem behaviours such as aggression, especially for those living in long-term facilities, public concern is growing due to polypharmacy (excessive use of multiple medications). These medications must be carefully monitored as they come with side effects such as hyperactivity, obesity and sedation. 

Medication should only be prescribed to those with ID if:

• Non-medication interventions have failed
• They are at risk of harm to others and themselves
• In the treatment of an underlying psychiatric disorder
• They have had a good response to medication in the past

Furthermore, medications are typically prescribed for the co-occurring disorder, such as with ADHD. The drugs effective in people with both ADHD and ID are non-stimulant drugs such as Atomoxetine, which increases attention and decreases restlessness to help with concentration.^9,10 However, research confirms that the general response rate to ADHD drugs for people with intellectual disabilities is 55% lower than the general population.⁹

Medical intervention is often insufficient in managing all symptoms of ID and co-occurring disorders, so a multi-disciplinary approach with behavioural therapies is often used. 

Positive Behaviour Support (PBS)

This is a person-centred framework which provides long-term support for those with ID. Problematic behaviour is often the only way the person knows how to communicate their unmet needs so PBS helps understand the reasoning for these behaviour to better understand people with ID.¹¹ This intervention has 3 stages: access, management and prevention. The access stage identifies the person's needs and abilities and analyses the purpose of the person's behaviour as well as their personal strengths. The manage model provides guidelines for how to respond to challenging behaviours and de-escalate them and finally prevention focuses on minimising anything that may trigger this behaviour. This framework is very individualised and ensures people are supported with empathy and a good level of care.¹² 

Why are medical interventions important within intellectual disability?

The Learning Disability Mortality Review (LeDeR) Programme by NHS England recently found a third of deaths recorded for people with ID were due to avoidable medical conditions.¹³ Furthermore, the life expectancy for people with ID is lower than for the general population with 6 out of 10 dying before age 65. 

This is due to many GPs still lacking specific education and training in learning disability health meaning they often face problems communicating effectively with their patient.¹⁴ 

This can therefore lead to the issue of overprescribing people with ID unnecessary medication or alternatively, not meeting their medicinal needs. 

Summary 

In summary, a multidisciplinary approach is needed in managing ID as medication can have adverse side effects and not treat the ID comorbidity effectively. Person-centred behavioural and pharmacological interventions are optimal in ensuring people with ID feel continuous support.

There needs to be an increased awareness of the medical interventions available for people with ID and how to correctly treat the disorders that co-occur to ultimately make intellectual disorders more manageable and improve people's day-to-day lives.