The brain does not mature until around the age of 25. Those who use cannabis while the brain is still developing are more likely to become dependent and suffer long-term health effects. Those who begin using cannabis at a young age are more likely to develop mental health problems. Cannabis use among youth is associated with depression, anxiety and psychosis. It is also linked to impaired neurological development, which can lead to difficulties with learning, concentration, memory, attention, and school performance. THC, the main active ingredient in cannabis, acts on targets found in the body known as cannabinoid receptors. These receptors are mostly found in the brain and central nervous system. When these receptors encounter substances found in cannabis it can affect the ability of the brain and central nervous system to function properly. Studies have shown that people who start using cannabis at a young age have experienced functional and structural changes to their developing brain, including alterations of white and gray brain matter.