Aggressive behaviour can be extremely difficult to deal with, both for the aggressor and the recipients of the aggression. The causes of aggressive behaviour are as varied as the ways in which aggression can manifest. The Mayo Clinic lists sudden aggressive behaviour as one of ten symptoms that should never be ignored (see References). Recognizing and understanding the various causes of aggressive behaviour is vital to coming up with a treatment plan with the help of a doctor or mental health professional.
Psychological disorders are the most common causes of aggressive behaviour. While almost any psychological disorder can be responsible for aggression, depression, bipolar disorder, schizophrenia, attention deficit hyperactivity disorder (ADHD), borderline personality disorder and post-traumatic stress disorder (PTSD) are among the most common underlying causes of aggression. Mothers suffering from postpartum depression are especially susceptible to aggressive outbursts, sometimes against the child. No psychological disorder or incident of extreme aggression should be taken lightly, and the symptoms of many psychological disorders subside or disappear completely when properly diagnosed and treated by a mental health professional.
Individuals with a history of migraines, strokes, epilepsy and even diabetes may be more prone to developing aggressive behaviours. Individuals with sleep disorders and Alzheimer's disease have also been shown to display aggressive behaviour as a result of their conditions. Physical disorders and diseases that go undiagnosed or untreated are more likely to cause aggression. In most cases, aggressive thoughts and actions caused by physical disorders can be minimised when properly treated by a medical professional.
The use of several types of illicit drugs can induce aggressive behaviour in many individuals. Intoxication from cocaine, amphetamines, LSD, ecstasy and alcohol often cause the user to become extremely agitated and violent. Withdrawal from nearly any illicit drug, including nicotine, may also be a contributing factor in causing an individual's aggressive behaviour. According to Dr. Robert Needleman, Vice President of Developmental & Behavioral Pediatrics at The Dr. Spock Company, some cases of aggression in children have been linked to exposure to smoking, illicit drug use or alcohol consumption while in the womb (see References)
Prescription drugs and interactions between them can result in aggressive behaviour. Surprisingly, lower doses of antidepressants, often given to children and teenagers because of their smaller size, may be responsible for aggressive outbursts as suggested in a study conducted by University of Texas scientist Kereshmeh Taravosh-Lahn (see Resources). Steroids and many tranquillisers have also been known to cause aggression in certain individuals. Those who are taking a variety of prescription drugs, especially those used to treat mental illnesses and disorders, may experience feelings and acts of aggression as a reaction to an interaction between medications.
Developmental disorders are often found to be the cause of aggressive behaviour, especially in young children. Adults who have a developmental disorder that has gone unnoticed or undiagnosed may find that the disorder manifests itself later in life in the form of aggressive or violent outbursts. Lead poisoning, iron deficiencies and even some environmental pollutants have been identified as the cause of developmental impairments in children that later led to aggression problems. Children with autism or severe mental retardation often experience aggressive episodes due to their inability to communicate effectively.