Depression and recreational drug use are both common and can occur together purely by chance as individual problems. More often, however, there is an interaction between the two and this can take several forms:

• a person may be suffering from depressive symptoms and take drugs in the hope of gaining some relief.
• depressive symptoms may develop as a direct result of taking drugs, or as part of withdrawal symptoms when drug-taking stops. (Low mood in withdrawal may be brief and self-limiting, but sometimes it can lead to a serious, prolonged depressive illness.)
• a person may take drugs to 'escape' from a problem during a particularly stressful time in their life; this stress may also be the trigger for an episode of depression.
• heavy drug use can lead to major financial problems, difficulties with relationships or trouble with the law. A person taking recreational drugs is likely to have more of these pressures, which may trigger depression.
• people who are depressed may use recreational drugs in an attempt to end their life.
• drug use is particularly common in other psychiatric illnesses (such as post-traumatic stress disorder or some anxiety disorders and phobias) that can also have depressive symptoms, even if the main problem is not depression itself.

Why do recreational drugs have these effects when people take them to feel good?

There are certain chemicals in the brain (called neurotransmitters) that are key to the way we feel - in other words they control our emotions. It is the levels of these chemicals that are altered in depression. Recreational drugs also affect these chemicals. This is why drugs alter the way we feel.

Neurotransmitters are affected by different drugs:

• dopamine is affected by cocaine, amphetamines and ecstasy.
• serotonin (or 5-HT) is affected by ecstasy and LSD.
• noradrenaline (Norepinephrine) is affected by amphetamines, opiates (heroin, morphine etc).

It is largely these three chemicals (dopamine, serotonin and noradrenaline) on which antidepressant medicines work.

So what does all this mean for someone who feels depressed and who is using drugs?

It means that to be able to help them effectively, doctors have to sort out what role the drugs play in the depression.

If the feelings of depression are simply part of the withdrawal from a drug and are temporary, it is unlikely that antidepressant treatment will be of benefit; antidepressants take an absolute minimum of two or three weeks to start working. The best help in this case is to try to help the person to get their drug use under control or stopped.

Both taking drugs and the withdrawal process can produce depressive symptoms, so it is very difficult to know exactly what is going on, even if it seems that the depression led to drug taking in the first place. As a result, it is vital to sort out the drug problem so it is possible to judge whether antidepressants or other treatments for depression are needed.

This doesn't mean it is impossible to treat the depression when someone is still taking drugs, but it does make it more difficult.

What should I do if I have this problem?

• Firstly, try to keep as much control as possible over your drug use so things don't get worse, and ask for help. You may need treatment for the drug problem, the low mood or both.
• Your family doctor will be able to advise you and, if necessary, arrange for you to see a general psychiatrist or a specialist in drug problems (often a psychiatrist, nurse or psychologist).
• It is important that you are honest about your drug use with any doctor, nurse or other professional you are seeing. Otherwise they will find it very difficult to work out how best to help you.
• Help from social services may be a good thing to ask for if you are running into problems with debts, housing, etc, as these can only make things worse if they don't get sorted out. Remember, such problems may have contributed to your difficulties in the first place.
• Another source of help might be voluntary drug agencies, if they are available in your area.

I think my friend or relative may have this problem

• Suggest to them that you have noticed there is something wrong. Ask them if they have considered asking for help from any of the sources mentioned above.
• It may be difficult if the person doesn't want you to know they have a drug problem: be diplomatic and encourage them to see someone about the depression. Leave the rest of the working out to the professional they see.

How do the different types of drug affect mood?

People often take more than one drug at a time and mix drug use with alcohol (which is itself a depressant), so it can be difficult to tell precisely which drug is affecting an individual's mood. Doctors do, though, have a good picture of what each drug can do from research in people who have taken only one drug at a time.

The drugs mentioned have many effects in addition to those listed, but for the purposes of this article we will concentrate on their effects on mood.

• Opioids: heroin (diamorphine), morphine, codeine, dihydrocodeine, pethidine, methadone (Physeptone), dipipanone (Diconal), dextromoramide (Palfium), buprenorphine (Temgesic), pentazocine, dextropropoxyphene (contained in co-proxamol), hydromorphone (Palladone).
  
  These powerful painkillers are used for their ability to produce a feeling of euphoria, but are potentially highly addictive. Heavy or long-term use can lead to temporary low mood or depressive illness. They can produce constipation and lowered appetite and sex drive - symptoms that are themselves associated with depression.
  
  Because these drugs produce a short-term feeling of wellbeing, it is easy to see how they might be used by someone who is feeling down to relieve their symptoms. Ultimately, though, they will make the problem worse.
  
   
• Barbiturates: amylobarbitone, pentobarbitone, quinalbarbitone, phenobarbitone.
  
  These used to be used to treat anxiety and sleep problems, but are now rarely prescribed. They are still used recreationally and are highly addictive.
  
  Depression is common in people who have been using them for some time, and occasionally the person's mood can swing between depression and euphoria. When the drugs are withdrawn unpleasant alterations in mood can occur, along with a tendency to burst into tears at the slightest problem.
  
   
• Benzodiazapines: diazepam (Valium), temazepam, lorazepam (Ativan), nitrazepam (Mogadon), alprazolam, oxazepam, chlordiazepoxide, clobazam, clorazepam, bromazepam, loprazolam, lormetazepam, flunitrazepam.
  
  The main problem with these drugs is they are often addictive if used for anything other than a brief period of time. Although the major difficulty in withdrawing from them is anxiety, some unpleasant changes in mood can also occur.
  
   
• Cannabis
  
  The effects of cannabis depend on the mood the person is in when they take it. Generally cannabis exaggerates the pre-existing mood, so if someone is a little down to begin with they can end up feeling desperately low until the effects wear off. In extreme cases they can experience suicidal thoughts.
  
  This state is usually relatively short-lived (up to a few hours), but there is evidence that some people who use a lot of cannabis over a long period may lose drive and motivation. This can be misinterpreted as depression, as can the irritability, reduced appetite and insomnia that some people get on withdrawal from using large amounts of the drug.
  
   
• Amphetamines and related drugs: dexamphetamine, phenmetrazine, methylphendidate (Ritalin), ephedrine, pseudoephedrine (Sudafed).
  
  These drugs are abused for their stimulant properties. Once they start to wear off, users find they have a 'crash' or come-down where they feel low, lack energy, are fatigued, anxious, and can feel shaky. This is usually temporary, but can be associated with suicidal ideas and can sometimes lead into a persistent depressive illness.
  
   
• Cocaine
  
  Cocaine users experience a come-down very similar to that of amphetamine. It lasts for around 24 hours after light infrequent use, but can be much more prolonged in people who use the drug heavily. It can be a stage on the way to developing more severe symptoms of hallucinations and paranoia. Suicidal feelings are not uncommon in the come-down period, and again this can turn into a prolonged depressive illness.
  
   
• Ecstasy (3, 4-methylenedioxymethamphetamine, MDMA)
  
  As it is a relatively more recent introduction to the drug scene, there is less information about ecstasy than there is about many other drugs. However, it is now well accepted that users can experience an unpleasant lowering of mood for up to three days after taking it, and that it occasionally causes episodes of severe depression to develop. It appears that long-term heavy use may predispose people to psychiatric illnesses in the future.
  
   
• LSD (lysergic acid diethylamide)
  
  While LSD has no clear withdrawal syndrome, it may occasionally be associated with marked depressive symptoms and suicidal ideas.

Mood problems associated with drug use can be complicated, but there is help available to work out what is going on and, if necessary, to treat the problems.