ADHD is considered a childhood disorder. However, adult ADHD afflicts approximately 30 to 50 percent of adults diagnosed with childhood ADHD (see Reference 1), which indicates the symptoms do not always subside. Diagnosing the disorder is difficult due to the many conditions that mimic ADHD. An accurate diagnosis is achieved by pinpointing the characteristics of ADHD throughout childhood, dating back to at least age seven. Additionally, hyperactivity, poor concentration and at least two more ADHD behaviors should be present (see Reference 1).
Depression
Depression and ADHD are equally common psychiatric disorders that cause mood changes. They can occur simultaneously, both appearing in childhood and continuing into adulthood (see Reference 2). Symptoms of depression that replicate those of adult ADHD include impaired concentration, restlessness and irritability. The most prominent symptom of depression is extreme sadness, which may lead to feelings of hopelessness and thoughts of suicide. Not all depressed individuals experience the same symptoms, however. In addition, the severity of depression varies from person to person.
Bipolar Disorder
Bipolar disorder, also known as manic-depressive disorder, is a mental illness that affects both males and females of all ages. The condition is thought to be caused by a chemical imbalance (see Reference 3) and like ADHD, it is often hereditary. Symptoms of bipolar disorder that may be confused with those of adult ADHD include feelings of anger or irritability, difficulty concentrating and frequent mood swings.
Addiction
Drug addiction is a dangerous and life-altering condition that affects the way a person thinks, feels and acts. The Mayo Clinic notes, the specific signs of drug abuse vary, depending on which substances are used. However, certain behaviors serve as warning signs. Similar behaviors appear in those with adult ADHD, including irritability, mood changes, restlessness and difficulty concentrating. In addition, complications common in ADHD and substance abuse include trouble with the law, problems at work and frequent car accidents (see Reference 4).
