Do psychological disorders cause other health problems?
Yes, it's common for people with mental illnesses be afflicted with other health problems that are exacerbated or caused by their mental illness. For example, people with depression have pleasure-reward centers in their brain that do not produce as much "happy chemicals" (dopamine) as healthy brains do. When a healthy person enjoys a slice of chocolate cake, the pleasure receptors in their brain more efficiently light up their reward centers and that healthy person is more easily satisfied with a small amount. A person with depression would need to eat more cake than a healthy person for their brain to produce the same amount of dopamine, which is why many people with depression and other mood disorders also suffer from binge eating and obesity.
Some mental illnesses such as depression and anxiety are known to cause many physical symptoms with no source. Joint pain, muscle aches, nausea and vomiting, headaches, racing heartbeat, and diarrhea are common. Many people don't realize they have a mental illness at first, and think the physical symptoms are signs of a physical illness or injury.
Certain mental illnesses can damage a person's organs or natural processes due to chronic stress. It's not uncommon for people with anxiety disorders to also suffer from hypertension, acid reflux/GERD, and stomach ulcers. These conditions can cause damage which leads to a higher chance of developing certain types of cancer.