Final answer:
The common condition in later life involving irritability, confusion, and delusions is Alzheimer's disease. It is marked by symptoms like severe memory loss, confusion, and personality changes. While schizophrenia, bipolar disorder, and OCD are significant mental health conditions, they are not characterized by confusion and delusions as the main symptoms and usually have an earlier onset than Alzheimer's disease.
Step-by-step explanation:
A common condition that occurs in later life and involves irritability, confusion, and delusions is Alzheimer's disease. Symptoms of Alzheimer's include disruptive memory loss, confusion about time or place, difficulty with planning and executing tasks, poor judgment, and personality changes. While some of these symptoms might be mistaken for normal aging, it is the severity and persistence of symptoms that characterize the disease. Alzheimer's disease is also associated with a decrease in brain cells and can sometimes present problems with smelling certain scents, which may serve as an early warning.
The other options listed, like schizophrenia and bipolar disorder, though serious mental health conditions, tend to have an earlier onset compared to Alzheimer's disease. Schizophrenia is known for symptoms such as hallucinations, delusions, and social withdrawal, typically diagnosed in late adolescence or early adulthood. Bipolar disorder is characterized by extreme mood swings and variations in energy and activity levels, not primarily by confusion and delusions. Obsessive-compulsive disorder (OCD) involves persistent, unwanted thoughts (obsessions) and repetitive behaviors (compulsions) but does not usually involve confusion or delusions.