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Dissecting addiction – looking at biology, genetics and the scale of the issue

Consultant Psychiatrist, Dr Pawan Rajpal, and the team at Priory Hospital Bristol, are preparing to launch their private inpatient addiction service later this year, to complement their current day care addiction programme. Dr Rajpal is an experienced mental health and addictions psychiatrist. He recently spoke to us about the biology and genetics behind addiction, the scale of the issue – both individually and on a societal level – and the targeted interventions that can help people to overcome their addiction.

Addiction is a psychological and physical inability to stop using a substance (such as alcohol, illegal or prescription drugs) or partaking in a behaviour (such as gambling, sex or work) even though the person knows that it is causing psychological and physical harm, as well as other negative consequences to themselves and those who are closest to them.

The common symptoms of addiction are obsession, loss of control, awareness of negative consequences yet continuing to drink, take drugs or participate in negative behaviours anyway, and the denial of the quantity of use. Addiction is a chronic, relapsing brain disease, and addiction to some substances can change the brain’s structure and function.

Addiction models

The brain is designed in such a way that there is a natural urge for people to continuously repeat ‘rewarding’ experiences. This is the biology of addiction. It works when these reward pathways in the brain are targeted and the chemical ‘dopamine’ is released, creating a euphoric feeling that people seek to replicate or ‘chase’. Wanting to continuously seek out this feeling can then lead to the individual repeatedly partaking in the behaviour (such as using heroin, drinking alcohol or gambling) which led to the ‘rewarding feeling’, resulting in negative consequences for the individual. Repeated and consistent use can also result in individuals developing a tolerance to the substance they are using, meaning they may have to ‘use more’ to get the same ‘high’ effect.

The addictive stimuli (the behaviour or the substance) is intrinsically rewarding and it results in a self-perpetuating cycle of continued use. If this behaviour continues over a period of time, ceasing can cause withdrawal. This can reinforce the behaviour of addiction, whereby the person loses control over their use to avoid withdrawal symptoms.

Genetics of addiction

Addiction is a disorder of the brain's reward system. Research shows that this is due to transcriptional and epigenetic mechanisms. The severity of these changes worsens over time, and is dependent on environment and exposure.

DeltaFosB (ΔFosB), is a gene transcription factor that is thought to be a critical component and common factor in the development of virtually all forms of behavioural and drug addictions.

Variations in expression of DeltaFosB, in the nucleas accumbens is associated with variation in addictive behaviours, and these changes can be causally connected.

Why bother with addictions

National statistics released by Public Health England show that opioids and alcohol remain the two most common substances used by those seeking addiction treatment. Opioids such as morphine, tramadol and fentanyl are super-strength painkillers, which can be highly effective for managing severe pain, but can also be very addictive and can kill if misused. The Department of Health has warned that the number of prescriptions in England and Wales issued for these sorts of medicines has risen dramatically, from more than 14 million in 2008 to 23 million last year. Looking specifically at codeine, the number of codeine-related deaths in England and Wales has doubled from 2008 to 2018. The Royal College of General Practitioners (RCGPs) said doctors would not prescribe opioid painkillers as a ‘quick fix’.

Looking across the Atlantic, alcohol, tobacco, illicit drug and prescription opioid addiction costs the United States economy upward of $740 billion each year. This figure includes the costs of treatment, lost work and the impact of addiction-related crime.


The bio-psycho-social model is an important element of addiction treatment and plays a bigger role in understanding, managing and addressing the issue of addiction than it does for other mental health problems. 

The bio-psycho-social model centres on supporting people through medications, psychology and social support.

Biological interventions

Biological interventions address the altered brain chemistry and the addiction susceptible reward cycle. Treatment includes medication, which can be used for:

  • Treating withdrawal – this can include physical effects and can precipitate life threatening conditions (such as withdrawal fits)
  • Replacement of essential nutrients, minerals and vitamins to avoid long-term memory damage
  • Reducing cravings
  • Treating challenges with sleep, anxiety, depression, restlessness and agitation
  • Maintaining compliance with treatment
  • Preventing relapse
  • Diagnosing and treating other underlying mental illnesses such as depression, anxiety, attention deficit hyperactivity disorder (ADHD) and post-traumatic stress disorder (PTSD)

Therapy as treatment

Therapy can help to address psychological and social addiction triggers, and can include:

Addiction causes an immense burden on individuals, families and on society as a whole. Research shows that a combination of the right diagnosis leading to appropriate medical treatment, along with robust psychological therapy and ongoing support can enhance the prognosis of the majority of people with addictions and reduce morbidity.

Get in Touch Today

For details of how Priory can provide you with assistance regarding addiction treatment and rehabilitation, please call 0800 144 8969 or click here to book a FREE ADDICTION ASSESSMENT. For professionals looking to make a referral, please click here

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