Physical problems can lead to mental problems

Are you crazy? No, you may be just sick.

More than 100 medical disorders can masquerade as psychological conditions, according to Harvard psychiatrist Barbara Schildkrout, author of Unmasking Psychological Symptoms, a book aimed at helping therapists broaden their diagnostic skills.

Studies have suggested that medical conditions may cause mental-health issues in as many as 25% of psychiatric patients and contribute to them in more than 75%, The Wall Street Journal reports.

Common culprits include under- or over-active thyroid glands, which can cause depression and anxiety, respectively. Deficiencies of vitamins D, B-12 and folate, as well as hormonal changes and sleep disorders have also been linked to depression. 

Diabetes, lupus and Lyme disease can have a variety of psychiatric symptoms, as can mercury and lead poisoning and sexually transmitted diseases. Many medications also list mood changes among their side effects, and substance abuse is notorious for causing psychiatric problems.

In some cases, a psychological problem is just the first sign of a serious medical issue. "Depression predicts heart disease and heart disease predicts depression," said Gary Kennedy, director of the geriatric psychiatry at Montefiore Medical Center in Bronx, N.Y.

Experts say mental health counselors should ask patients about their medical histories as well as emotional issues, and make sure they've had a recent physical exam.