Cannabis abuse is the misuse of the drug cannabis, which is derived from the Cannabis sativa Linnaeus plant. It is sought out for its effects of relieving anxiety and producing euphoria. In the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), cannabis abuse is part of cannabis use disorder.
In the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5), cannabis abuse constitutes one part of cannabis use disorder (CUD). The subsequent component of CUD is cannabis dependence. There are certain criteria used to diagnose the disorder, and these incorporate both the acute and chronic effects of cannabis use.
A mental status examination (MSE) should be carried out, as cannabis use alters mentation. There are specific aspects of mental function that are typically affected. These include mood, affect, thoughts, and cognition. Mood and affect manifestations differ acutely and chronically. In acute intoxication, patients may display a relaxed or euphoric mood, excessive laughter, and congruent affect. In chronic cases, the mood may be negative, for example, depressed, irritable, anhedonic, suicidal or homicidal. The affect is often restricted. Thought and perceptual disturbances include loosening of associations, and in some cases, hallucinations and delusions. Cannabis abuse can also lead to reversible cognitive impairment, compromising both memory and concentration  . Furthermore, individuals often demonstrate a decreased interest in daily activities and a low level of motivation.
The hallmark signs of acute cannabis use, appearing hours after smoking, are redness of the eyes, dry mouth, and increased appetite . In addition, tachycardia is also common. Other physical signs and symptoms include visual disturbances, sweating, headaches, and impaired motor abilities. Psychiatric effects include anxiety, paranoia, labile mood, forgetfulness, poor concentration, and psychotic features. Symptoms disappear after 2 to 3 hours.
Cannabis abuse may interfere with various aspects of life, such as social interactions and financial stability. It is often used by drug abusers as a second drug, in combination with other drugs .
The complications of cannabis abuse include the worsening of pre-existing psychiatric disorders, as well as the occurrence of new psychotic disorders, such as schizophrenia. The risk of schizophrenia is magnified with earlier onset of use, especially before the age of 15 years . Further, depression and dependence are recognized complications of cannabis use . The latter particularly poses a challenge to treatment . Moreover, there is an increased lifetime risk of both depression and anxiety disorders in users. Cannabis dependence can lead to withdrawal symptoms, but these are usually less severe in comparison to various drugs of abuse . This is more commonly seen in long-term users .
Systemically, it has been shown that there is temporary damage to the respiratory system, that resolves upon cessation of smoking cannabis . There is, however, no confirmed link between cannabis use and acquiring chronic obstructive pulmonary disease (COPD) or lung cancer.
Cannabis abuse, as part of cannabis use disorder, is categorized into mild, moderate, and severe. The diagnostic procedures include a physical examination as well as an MSE. The DSM-5 definition and criteria for cannabis use disorder stipulate that an individual must have clinically significant impairment of functioning in two or more areas, for at least one year. The list of criteria includes: taking increasingly large amounts of the drug, cravings, strained interpersonal relationships, a significant amount of time dedicated to use of the drug, tolerance, development of dependence, and the occurrence of withdrawal symptoms upon withdrawal of the drug.