Another common overlooked factor is hypothyroidism, which is on the rise. Hormone imbalances, xenoestrogens, estrogen replacement therapy, use of stimulants (caffeine, nicotine, etc.), stress, chlorine in pools and added our water, bromine from spas, and fluoride added to our water, toothpaste and other products are a few of the contributors to the rise in hypothyroidism.
A symptom of hypothyroidism is depression.
Another little known cause of depression is the use of nonsteroidal anti-inflammatory drugs (NSAIDs). These include aspirin, ibuprofen (Advil, Motrin, Nuprin, etc.), celecoxib (Celebrex), naproxen (Naprosyn), etc. These are prostaglandin inhibitors, which are hormones that among other things counter depression.