Psychoactive Effects of Weed: What THC Does to Your Brain (and Why CBD Doesn't Get You High)

The psychoactive effects of weed come mainly from THC and include euphoria, relaxation, giggles and a warped sense of time and space, along with short-term memory and attention changes; how strong they are depends on the strain and how much you take. Cannabis has been used for centuries for both its mind-altering and medicinal effects, and its popularity has grown massively in recent decades.

From euphoria and relaxation to shifts in how you perceive time and space, these effects can have a deep impact on people and their experience. Understanding how weed affects the mind and body is essential to any conversation about using it, whether recreationally or for medical reasons.

Psychoactive vs. psychotropic: what's the difference with cannabis?

Cannabinoid research mainly draws a line between THC, the psychoactive compound par excellence, and CBD, the best-known non-intoxicating cannabinoid.

THC affects mood, sensitivity and how you perceive reality, but not every cannabinoid that acts on the central nervous system (CNS) produces a high like recreational weed does.

CBD, for its part, is technically psychoactive in the sense that it can influence the central nervous system, but it doesn't cause intoxication.

Put simply, a psychoactive cannabinoid affects the CNS without altering sensory perception, while a psychotropic cannabinoid, like THC, can change sensory perception and produce an intoxicating high.

Psychoactive vs. psychotropic: the bottom line

Even though CBD and other cannabinoids can influence mood and other brain processes, they don't cause the psychotropic effects associated with THC. That's why CBD is valued for its therapeutic potential in conditions like epilepsy, and is being studied for Parkinson's, without THC's unwanted effects.

In short, THC and a few other cannabinoids, like THCV and CBN, are classified as psychotropic because of their intoxicating effects, while CBD shows significant therapeutic potential without producing them, which is why it's described as non-psychoactive in this scientific context.

How cannabinoids affect the central nervous system

Cannabinoid receptors and how they work

The endocannabinoid system (ECS) includes cannabinoid receptors, the body's own cannabinoids (endocannabinoids) and the enzymes that build and break them down. When it was first discovered, understanding was limited and there was heated debate over medical cannabis and its potential for abuse and dependence.

Since then, research has dug much deeper into the key compounds in cannabis, their properties and how they act throughout the endocannabinoid system. One standout area is the ECS's ability to modulate immune function within the nervous system.

The best-studied receptors are CB1 and CB2, which are G protein-coupled receptors (GPCRs) that regulate a wide range of physiological responses, including hormonal and neurotransmitter responses and reactions to environmental stimuli.

THC as a psychoactive and medicinal compound

THC is recognized as the main psychoactive compound in cannabis and produces most of its medicinal effects by interacting with CB1 and CB2 receptors. These receptors, which have seven transmembrane domains, are coupled to inhibitory G proteins and regulate signaling cascades that affect intracellular calcium levels, involving adenylyl cyclase, cAMP and MAP kinases.

What do CB1 and CB2 receptors do?

The CB1 receptor is widely expressed in the central nervous system and other organ systems. It helps regulate pain, stress, fat metabolism and immune function, and recent research shows it's central to THC's psychotropic effects.

The CB2 receptor, by contrast, is mainly tied to immune function and is found on immune cells, including the nervous system's microglia, although it's far less present in the CNS than CB1.

Other receptors cannabinoids interact with

Beyond CB1 and CB2, cannabinoids can bind to other receptors like GPR55, whose response varies with the dose of THC, the main cannabinoid in cannabis plants (acting as an agonist at low doses and an antagonist at high doses) and is also modulated by CBD, some synthetic cannabinoids and endocannabinoids like anandamide (AEA) and 2-arachidonoylglycerol (2-AG). Unlike CB1 and CB2, these receptors raise intracellular calcium levels when activated.

In short, cannabinoids have a significant impact on the central nervous system through complex interactions with the endocannabinoid system and its various receptors. Ongoing research promises to reveal more about how these interactions could be put to therapeutic use across a range of medical conditions.

Effects of weed: benefits and risks

What delta-9-THC does to your mind

Delta-9-THC, the main psychoactive compound in cannabis, produces the same psychological changes people experience from smoking weed. Delta-8-THC is somewhat less potent and shows up in smaller amounts, but it can still add to the high.

Cannabinol (CBN), on the other hand, produces no noticeable physical changes when taken orally at high doses, but given intravenously it can cause psychotropic effects similar to cannabis.

CBD and other cannabinoids: do they get you high?

Cannabidiol (CBD), taken orally or intravenously at doses far higher than the active dose of delta-9-THC, is considered inactive in psychotropic terms.

Studies in primates and other animals have shown that cannabinoids like delta-8-THC and CBN are less potent than delta-9-THC, while CBD has no significant psychotropic effects.

Psychotropic effects seen in animal studies

Experiments with rhesus monkeys, squirrel monkeys and dogs have shown that several cannabinoids can trigger behavioral changes comparable to those seen in humans in psychopharmacology research.

These effects include stimulation of the limbic system's dopamine pathway and, in people, laughter, changes in visual perception, distorted sense of object size, and altered time perception and short-term memory, among others.

Why the high varies so much

The psychotropic effects of cannabinoids vary a lot and can be strongly shaped by social and environmental context (your set and setting). They can affect mood, visual and spatial perception, memory and selective attention. Because these effects come and go, your sense of time and space can fluctuate during a high.

Why cannabis studies are tricky to interpret

Interpreting cannabis research can be complicated for several reasons: the sheer variety of compounds in the plant, differences in chemical makeup due to processing and storage, and the interactions between cannabinoids and the plant's other components.

Bottom line: psychotropic cannabinoids like delta-9-THC and CBN have significant effects on behavior and perception, shaped by a range of factors that need to be taken into account in both research and clinical use.