What are the effects of antidepressants on ADHD?
Though antidepressants are chemically different from stimulants, they have similar effects on the key symptoms of ADHD: attentiveness, impulsivity, and hyperactivity.
Compared to the stimulants, antidepressants are slightly less effective, and they have higher risk of serious side effects. In addition, antidepressants must accumulate in the body to be effective; stimulants don't. For all these reasons, most doctors prefer to start with stimulant therapy and substitute antidepressants if the stimulants don't work or have unacceptable side effects. For people who have both ADHD and depression, antidepressants are the preferred choice.
What are the key benefits?
Antidepressants have some advantages over stimulants. They work for longer periods of time, so it's often possible to use twice-a-day dosings (morning and evening), eliminating the problem of giving doses during the school day. Also, the doctor can use a blood test to measure the amount of medication actually circulating in the bloodstream; this can be useful to determine whether the drug is working as it should and to monitor for too high levels.
What are the drawbacks?
The biggest drawback with these drugs is that they have to build up in your system to be effective. That makes it harder to fine-tune treatment. Also, you can't stop treatment suddenly; you have to taper off the medication level over three to four weeks.
And because they have to build up over time, they never completely clear out of your system. Stimulants, by contrast, are completely eliminated from your body within a few hours.
In general, tricyclic antidepressants are better suited for adolescents and adults than children. When children use them, the best strategy is to start with a low dose (for example, 10 to 25 mg of desipramine) broken up into three or more doses if possible, then increasing the dosage gradually over several weeks, up to a maximum of 125 mg a day. Most patients won't need such high doses, however, and by phasing in the dose this way, the doctor can monitor the medication for its effectiveness and potential side effects.
Though the risks of heart problems are slight, most experts recommend that anyone taking tricyclic antidepressants get an electrocardiogram (EKG) regularly. The EKG, which monitors the heart's rhythm, can provide early warnings of heart-related problems.
How do these drugs work?
Antidepressants, like stimulants, affect how your brain uses neurotransmitters. They seem to work by preventing the breakdown of neurotransmitters after they're released from the nerve ending. As a result, they increase the amount of neurotransmitters that are present between nerve cells, thereby helping to transmit the signals more effectively.
Though they work by a different mechanism than the stimulants, the end result is largely the same: more neurotransmitters are available to transmit messages between nerve cells.
What kinds of side effects can I expect to see?
Antidepressants' side effects are usually less severe than those of stimulants. The most common side effects-occurring in about one fourth to one third of cases-include dry mouth, decreased appetite, headaches, nausea, fatigue, dizziness, and insomnia. Occasionally they increase heart rate and blood pressure, but these effects are usually insignificant at the low doses used to treat ADHD.
Can these medications be used if my child is on other medications?
It depends on the medication and type of antidepressant. One strategy we sometimes use for ADHD is to combine certain antidepressants with stimulants. That allows us to use lower doses of each, and take advantage of their complementary benefits: Because antidepressants are long-acting, we can use lower doses of them to provide a baseline level of focus. But stimulants provide better focus, so we can use them as supplements--again in lower doses--at critical times such as school to provide more complete control. This approach often allows us to prevent the ups and downs that occur with short-acting stimulants, and can help reduce side effects since we're using lower doses of both medications.