Originally Posted by meyaj
Generally if anything, antidepressants are considered to protect the nervous system.
The problem with this whole question is that, particularly when you're asking for an individual's answer, if it's anecdotal/experience-based, it's pretty impossible to separate what long-term stuff has been a result of the drug, and which is a result of the long-term condition itself.
Depression has been shown to cause the hippocampus to atrophy, grey matter to reduce, and increase production of inflammatory proteins. Surely all of these things could cause cognitive decline, and worse, which people might wrongly attribute to the drugs they're on because they mistakenly believe that depression is simply a condition of the mind and not a physical disease.
Conversely, even SSRIs have been shown to stimulate neuronal growth in the hippocampus and reduce pro-inflammatory proteins. I would say these are very good and important long-term effects.
Withdrawal CAN suck, but people are mistakenly calling it a long-term effect when it's not, though it IS obviously caused by long-term use. Withdrawal is very short-term. It also depends on the antidepressant, as some, like Effexor and Paxil, are considered to be much worse than others (eg Prozac), which many people don't notice any withdrawals for. There are some drugs (GABA agonists like benzos and alcohol are particularly notorious) that can lead to PAWS (post-acute withdrawal syndrome) which is like a very long-term withdrawal with milder symptoms, though the sheer duration and hopeless-feeling of it is often reported by drug addicts to make it harder to stay off a drug then the more immediate and intense withdrawals. As far as I know, it's never been reported with anti-depressant use, though depression is a major symptom so I guess it could easily get confused with relapse, though if you're getting treated for depression in the first place it shouldn't make a difference. However, long-term opiate users report experiencing PAWS for months afterwards, and very long-term GABA-agonist (benzos, alcohol, barbiturates) users sometimes experience it for YEARS.
Basically, there's been enough research in adults to rule out any safety issues with long-term use of most antidepressants. There are some exceptions, but they generally have nothing to do with their function as an antidepressant. Cymbalta, for instance, has been reported to cause liver failure in a few cases and some degree of liver damage in many more. Nardil also has a certain degree of liver toxicity. Though since the liver plays the key role in processing the majority of xenobiotics (drugs and other foreign chemicals), it is not unusual that this organ in particular seems to be a target for damage. Certain antidepressants that have been taken off the market (and some that are still available as OTC supplements... OTC does not imply safety) have been known to cause heart-valve damage through a very well-documented mechanism.
In general though, long-term health, cognitive function, and life-span can be expected to IMPROVE with the use of antidepressants, particularly in adults who need it. Some of it comes from documented physical effects of antidepressants that I've mentioned above (neuroprotection, hippocampal growth, decreased pro-inflammatories), some of it comes from the fact that people with properly treated depression can usually be expected to be more active and treat themselves, their health, and their hygiene better than depressed individuals do, and a very small amount of statistical benefit could be expected to come from a reduction in suicide. Overall, anybody with depression considered to be worse than simply mild should really do whatever they can to try and treat themselves (in an intelligent, rather than reckless manner of course), as at this point, potential benefits generally far outweigh the costs.