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.
Paranoia is a symptom that can be part of several syndromes, including delusional disorder, paranoid personality disorder, psychotic disorders such as schizophrenia, and mood disorders, including bipolar disorder, as well as other conditions (such as brain toxicity that may be caused by drug or alcohol abuse, types of poisoning, etc).