This is a question that is asked a great deal (and for good reason), so I'm going to list my go-to resources here:

http://www.schizophrenia.com/sznews/archives/004348.html#

http://www.psychiatrist.com/pcc/pccpdf/v05n06/v05n0603.pdf

Strongly suggest reading this one:

http://www.nytimes.com/2011/11/22/health/for-some-psychiatric-troubles-may-begin-with-the-thyroid.html?_r=1&

Excerpt from the NYT article above that I would strongly recommend reading in its complete form:

In a sense, she was lucky; her hormone levels were clearly in the abnormal range. “Normal” levels of thyroid stimulating hormone, or TSH, range from 0.4 to 5. (The higher the TSH level, the less active the thyroid.) Most endocrinologists agree that a score of 10 or over requires treatment for hypothyroidism.

But for people with scores between, say, 4 and 10, things get murkier, especially for those who experience such vague psychiatric symptoms as fatigue, mild depression or just not feeling like themselves.

Some doctors believe these patients should be treated. “If somebody has a mood disorder and subclinical hypothyroidism, that could be significant,” said Dr. Thomas Geracioti, a professor of psychiatry at the University of Cincinnati College of Medicine.

Dr. Geracioti has used thyroid hormones to treat performers with debilitating stage fright; one high-level musician recovered completely, he said.

The idea of treating subclinical hypothyroidism is controversial, especially among endocrinologists. Thyroid hormone treatment can strain the heart and may aggravate osteoporosis in women, noted Dr. Joffe. On the other hand, failing to treat the condition can also stress the heart, and some studies suggest it may increase risk of Alzheimer’s disease and other dementias.

And then there is the misery quotient, which is hard to quantify. “People tend to discount the quality-of-life issues related to residual depression and anxiety,” Dr. Joffe said.

Women are far more likely to develop thyroid problems than men, especially past age 50, and some experts believe that gender accounts for some reluctance to treat subclinical disease. “There’s a terrible bias against women who come in with subtle emotional complaints,” Dr. Davis said. “These complaints tend to be pushed aside or attributed to stress or anxiety.” "

YES hypothyroidism can cause wicked mental manifestations - and some folks are labelled as bi-polar or schitzo when they have a physical problem.

Here's more on that:

http://www.thyroid.ca/e10f.php

Psycho or Hypo?
https://www.facebook.com/notes/thyroid-sexy/psychiatric-manifestations-of-thyroid-disease/556815334337426

http://www.stopthethyroidmadness.com/thyroid-depression-mental-health/

http://evolutionarypsychiatry.blogspot.com/2012/02/thyroid-and-psychiatric-illness.html

http://thyroid.about.com/cs/basics_starthere/a/couldyou.htm


From NYT Article:
"Women are far more likely to develop thyroid problems than men, especially past age 50, and some experts believe that gender accounts for some reluctance to treat subclinical disease. “There’s a terrible bias against women who come in with subtle emotional complaints,” Dr. Davis said. “These complaints tend to be pushed aside or attributed to stress or anxiety.”

Psychiatric symptoms can be vague, subtle and highly individual, noted Dr. James Hennessey, director of clinical endocrinology at Beth Israel Deaconess Medical Center in Boston.

Another complication: It’s not clear to many experts what “normal” thyroid levels really are."


As one very good doctor and friend once told me - "crazy people do not KNOW they are crazy. The fact that you ask the question tells me you are not crazy"

If anyone has other resources to add, please do so - it's very important to raise awareness that hypothyroidism is OFTEN mis-diagnosed as a "mental illness".