Depression is one of the most common psychiatric symptoms in Alzheimer’s disease and occurs at all stages of the disease, but it manifests in ways that are different from other depressive disorders. In 2000, a task force at the National Institute of Mental Health created a set of provisional criteria for diagnosing depression in Alzheimer’s disease, as a separate diagnostic entity in its own right. In 2005, a group of psychologists at Johns Hopkins University created a set of working criteria to help diagnose depression in Alzheimer’s disease in clinical practice. Although caregivers often feel that a diagnosis of Alzheimer’s disease must generate depression in a person with the disease, there is little or no evidence to support this. In fact, it is unclear how many individuals come to terms with their diagnosis of Alzheimer’s disease at the time of its occurrence. Symptoms of depression in Alzheimer’s disease can arise at any point in the course of the disease, and are most evident in the later stages of cognitive decline. Several neurological studies have found a relationship between abnormalities in the brain and depression in dementia. Specifically for Alzheimer's disease depression, PET studies have found metabolic changes in the superior frontal gyrus. The diagnostic criteria for Alzheimer's disease depression require three of the possible symptoms of major depressive disorder rather than the five required for major depressive disorder itself, and the symptoms can be variable. Thus, Alzheimer's disease depression is often not recognized in the spectrum of Alzheimer's disease symptoms. In general, individuals with Alzheimer's disease depression tend to be anxious, agitated, delusional, or absent-minded. Symptoms include irritability, irritability, and social withdrawal. Individuals with Alzheimer's disease depression are more likely than individuals with major depressive disorder to show a decrease in their enjoyment of socializing or traditional activities, but they are less likely to express guilt or to feel suicidal or to attempt suicide.