Paranoia refers to persistent and irrational suspiciousness, mistrust, or the belief that others intend to harm, deceive, or exploit an individual. It may occur as a symptom in several psychiatric disorders such as paranoid personality disorder, delusional disorder, schizophrenia, bipolar disorder, major depressive disorder with psychotic features, and substance-induced psychotic disorders. The causes of paranoia are complex and involve the interaction of biological, psychological, and social factors. Biological factors play a significant role in the development of paranoia. Genetic influences increase vulnerability, as individuals with a family history of schizophrenia or psychotic disorders have a higher risk of developing paranoid symptoms. Brain abnormalities involving the prefrontal cortex, temporal lobes, and limbic system can affect judgment, emotional regulation, and interpretation of social information. Neurotransmitter imbalances, particularly excessive dopamine activity, are strongly associated with paranoid delusions. Disturbances in serotonin and glutamate systems may also contribute. Certain neurological conditions such as dementia, epilepsy, Parkinson's disease, brain tumors, traumatic brain injury, and stroke may produce paranoid thinking. Psychological factors are equally important. Individuals with low self-esteem often