Thyroid disease in cats is linked to heart disease and a fast heartbeat in conjunction with any other symptoms of thyroid problems is cause for a trip to the vet. Once the hyperthyroidism is treated, your cat's heart rate should return to normal.
Stress reaction â some studies have found that paranoia is more common in people who have experienced severe and ongoing stress â for example, prisoners of war. How stress can trigger paranoia is unclear.
Stress can cause headaches, high blood pressure, insomnia and, yes, tummy trouble. Depression has been linked with digestive problems (including loss of appetite and weight loss) as well as irritable bowel syndrome. The relationship seems to go both ways, according to a study published in 2012 in the journal Gut.