Depression caused by physical conditions and medications


In most people, depression is due to stressful events wearing down your ability to resist, and eventually causing your chemistry to change.  However, in a small number of cases, physical illnesses, viruses, or prescribed medications can in fact cause depression, and treatment of these physical conditions or stopping the medication will usually (but not always) allow the depression to subside.



“After the flu’ comes the blues”.  This piece of jargon in psychiatry is in recognition of the very frequent occurrence of depression after a virus infection, such as the flu’, but also after any other virus infection.  Glandular fever (infectious mononucleosis) is notorious for causing prolonged episodes of depression after the physical condition has settled down.


There is no easy way of confirming whether or not a person has had a virus which has caused their depression, but feeling physically unwell for a few days or more, especially accompanied by hot and cold feelings or sweating, all suggest a virus has been at work.


Unfortunately, if the virus has managed to push your chemistry into an episode of depression, you will then need treatment for your depression, despite the fact that the virus has gone away or been inactivated by your immune system.  If you do not get treatment for an episode of depressive illness, the episode can last an average of six to twelve months, and also increase the chances of further episodes of depression in the future.


Under-active Thyroid Gland

The thyroid gland, situated in your neck, is like the carburettor of a car, determining how quickly or slowly your body metabolism ticks over.  If your thyroid gland is under-active, you are at increased risk of developing depression, or of developing dementia as your brain is slowed down.  A simple blood test will determine whether or not you suffer from this condition, but the standard features of an under-active thyroid gland are feeling colder than usual, or colder than the people around you, and gaining weight without any significant change in your diet or exercise.


In those people whose thyroid gland problems are caused by their immune system accidentally attacking their own thyroid gland (what is called an ‘auto-immune disease’), the under-active thyroid gland has often been preceded by the opposite symptoms, namely marked anxiety and over-activity, together with feeling hotter than usual, and losing weight without trying to do so.


Cancer and Tumours

In rare cases, depression is the first signal that the person actually has cancer.  However, let me emphasise that this situation whereby someone with depression turns out to have underlying cancer, is in fact very rare.  However, if you have had some treatment for depression, and you are not responding to treatment, your doctor will presumably want to consider this possibility, and perhaps carry out some of the blood tests and radiology investigations described below.


Other physical illnesses

There is a whole range of illnesses affecting the human body, which have depression as a complication of these illnesses.  In particular, they include illnesses affecting your chemistry, your immune system and your hormone system.  Furthermore, if you have any long term illness or long term pain, it is very common for about one third of people with these conditions to develop depression as a complication of their illness.  Treating the physical illness only will not always allow the depression to subside, and it is often necessary to treat the depression also, to improve the person’s quality of life as far as possible.



Symptoms suggesting underlying physical illness

There are a number of factors which increase a psychiatrist’s suspicions that an illness may be due to underlying physical disease.  Some of these factors are:-

  1. the presence of intellectual difficulty, such as being unable to recite the months of the year in reverse order, or being unable to spell reasonable length words backwards;
  2. seeing  things that are not there (visual hallucinations); this can also be caused by ingesting or withdrawing from alcohol and illicit drugs
  3. very  unusual symptoms, such as experiencing intensely strange smells which nobody else notices;
  4. depression that is not responding to 2 or 3 different types of antidepressant;
  5. episodes of confusion.


Blood tests and X-rays

For any serious or prolonged condition, it is usually a worthwhile and relatively cheap precaution to carry out a range of simple blood tests and X-rays, which can identify if there is a physical contribution that may be causing depression.  The standard blood tests ordered by doctors in these situations are full blood examinations, ESR (a measure of inflammation in the body), thyroid function test, liver function test, kidney function test, and a measurement of the level of blood sugar.  There are rare cases of depression caused by abnormalities affecting calcium, phosphate, Vitamin B12 and folic acid (Vitamin B10).  Out-ruling AIDS and other serious sexually transmitted diseases, such as Syphilis are sometimes important.  If the symptoms you have described to your doctor make him suspect any other physical condition, he or she will presumably order other more specific blood tests.


A chest xray and a CT (CAT) brain scan are sometimes done also to out-rule rare conditions such as lung cancer or a brain tumour.  MRI scans give even more precise details of brain and body structure.


As yet, there are no Xray scans such as PET scans which can confirm who has any particular emotional illness, including depression.


Important Disclaimer:  This site is medical information only, and is not to be taken as diagnosis, advice or treatment, which can only be decided by your own doctor.

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