I have had problems with anxiety and feeling like I was malnourished, and realized that the result of that could cause negative health in several areas of life for me. I didn't link it to a specific physical disease, but would often obsess over mental illnesses and think "what if I have this, what if I have that?". Fortunately, you can move on from that with some help, whether it be speaking with someone (which I recommend), possibly trying out some medication from a psychiatrist, or trying to rely on other resources found in books, videos, online etc. I try to do all three haha.
GoldeWolf - Depression can cause this, but depression creates anxiety; anxiety creates depression. It is a difficult cycle to break out of. Try to get some help for depression. Also, look to your diet. Cut out caffeine (can cause anxiety), alcohol (which is a depressant), refined sugar, the nasty artificial sweeteners. Eat vegetables and fruit, and do exercise. Your body and mind will thank you! Meditation to control the thoughts, and anxiety has helped me tremendously. Exercise, if done consistently, can boost your mood, as it raises your endorphin levels and oxygen to the brain. Low Vitamin D was a culprit in my case. Daily supplements were increased (by my doctor) and I have seen a real difference, even when the weather is cold, gloomy and rainy. Exercise and diet are so essential to health! Drugs are just a patch, and do not solve the real problem, in my opinion, but sometimes create more problems.