While LSD may not be physically addictive, there is still a risk of psychological addiction. There are several biological processes which influence this, including:

• Dopamine System
• Reward Pathway: The brain's reward system, particularly the mesolimbic dopamine pathway, is heavily involved in addiction. When a person uses LSD, it can stimulate this pathway, leading to feelings of pleasure and reinforcement of the behavior.
• Dopamine Release: Although primarily affecting serotonin receptors, LSD can also influence dopamine levels, enhancing the sense of reward and pleasure.
• Serotonin System:
• Serotonin Receptors: LSD acts primarily on the serotonin (5-HT) receptors, especially 5-HT2A receptors. This interaction alters perception, mood, and cognition, which can be highly reinforcing.
• Altered Perception and Mood: The profound changes in mood and perception caused by LSD can make users crave these altered states, contributing to psychological dependence.
• Neuroplasticity:
• Learning and Memory: Repeated use of LSD can lead to changes in synaptic plasticity, which affects learning and memory. This can create strong associations between the drug and certain environments or experiences, reinforcing the desire to use it.
• Conditioned Responses: Over time, cues associated with LSD use (like specific places or people) can trigger strong cravings and psychological dependence due to these learned associations.
• Prefrontal Cortex and Decision Making:
• Impaired Judgment: LSD's impact on the prefrontal cortex can impair decision-making and self-control, making it harder for individuals to resist the urge to use the drug.
• Increased Salience of Drug-Related Cues: The prefrontal cortex helps assess the importance of different stimuli. LSD can make drug-related cues more salient or noticeable, increasing the likelihood of repeated use.

As discussed above, use of LSD does not lead to physical addiction in the way that other drugs such as cocaine can, but use of LSD can lead to behavioural addiction and tolerance, causing a user to require more of the drug, much like a true addiction.

Environmental Factors

Regular use of LSD can lead to a tolerance for the drug, causing the user to take higher doses more frequently to get the same hallucinatory effects.

Psychological Factors

People who are susceptible to peer pressure may be more likely to develop an LSD addiction, alongside individuals who engage in risk-taking behaviour.

Hallucinogens such as LSD induce significant physical and behavioural changes. Although they are the direct result of the effects of the drug, rather than a physical addiction, there are a number of physical and behavioural symptoms to look out for if you or someone you know has a problem with LSD.

Physical Symptoms

• Dilated pupils
• Nausea
• Increased heart rate
• Dry mouth
• Weakness and tremors
• Tingling in fingers and toes
• Sweating or chills
• Blurred vision
• Loss of coordination
• Impulsiveness
• Seizures
• Hallucinations

Behavioural Symptoms

• Anxiety
• Depression
• Paranoia
• Aggression
• Suicidal thoughts

LSD abuse – and indeed drug abuse of any kind – is different to LSD addiction. Drug abuse is often the first step on the road to addiction. LSD abuse can lead to mental disorders, flashbacks and severely impacts on your ability to handle your usual responsibilities, for instance going to work. LSD ‘addiction’ develops when you seek the drug more frequently in order to experience the trip, and when you develop a tolerance to the drug causing you to increase the dose. This increased tolerance often leads to needing a full LSD detox.