TL;DR version: Mental illness is probably much worse than poverty or physical illness. Interventions which change how people think - i.e. reduce mental illness and increase happiness - may be more cost-effective ways of increasing happiness than AMF or Give Directly. I outline some new opportunities EA should look into.
Update (18/06/2017): this paper is now slightly out of date. It doesn't reflect my latest thinking and contains some errors. For one, it was unhelpful to compare saving lives (preventing premature deaths) to improving lives (increasing the average happiness within a life) as there are multiple views you can have about the value of saving lives. For more on that, see this post questioning anyone should want to give to AMF.
I don't really use the forum but I've been encouraged by others (Rob Wiblin of 80k, Joey Savoie of Charity Entrepreneurship) to share some of my research I've discussed with them here. I've written a 5,000 word draft paper "What should a billionaire do to maximise world happiness" as a potential draft chapter in my PhD where I argue EA currently overlooks human happiness and mental health.*
Here's the summary of main points which I discuss in greater depth in the draft:
1. Effective altruism has so far focused on "external happiness interventions" (EHIs) which aim make people happier by changing their external circumstances (e.g. poverty, malaria). It's neglected "internal happiness interventions" (IHIs) which try to increase happiness by changing how people think (e.g. mental health treatments).
2. It's very plausible, but as yet untested, that some Internal Happiness Interventions might turn out to be more effective than our current EHIs such as Give Directly or AMF.
3. Mental health and ordinary human unhappiness (e.g. 'normal' stress, worry, sadness) are big. The former affects 700m+ (depends how you count it) and everyone suffers from the latter.
4. Our intuitions about how happiness works are very misleading. We adapt to lots of changes (hedonic adaptation) are a very bad at correctly predicting how we'll feel in the future (affective forecasting). For instance, people in poverty are not as unhappy as you imagine they are.
5. It's questionable whether cash transfers to those in poverty will increase happiness. The only RCT into Give Directly showed their cash transfers had no long-term effect on life satisfaction scores. The trial showed GD's recipients did have increased life satisfaction in the short-term (6 months) but that the non-recipients had their life satisfaction go down by more than recipients' went up. This suggest Give Directly's work does not increase happiness (taking 'happiness' as 'life satisfaction'). More research is needed.
6. QALYs/DALYs very likely underrate the badness of mental health conditions on happiness. First, they are measures of health, not happiness. Second, their weighting are creating by asking people how bad they expect various conditions to be, rather than assessing asking people with those conditions to report their subjective well-being. As mental health conditions are hard to imagine and hard to adapt to, their are underrated. As a estimate that can definitely be argued about, they might be 10-18 times worse than we imagine them to be.
7. Putting all this together, I guess that mental health and ordinary human unhappiness cause 4-72 times more misery each year to living people than do poverty and malaria combined (see Annex B of my paper). This shouldn't be taken too seriously, it's just to get a sense of scale.
8. Mental health and ordinary unhappiness unhappiness might be surprisingly tractable. There are quite a few methods which seem to work for both of them: cognitive behavioural therapy, mindfulness-based stress reduction and positive psychology to name the most promising. They can be delivered in person and, also exciting, electronically. Anti-depressants also seem to be somewhat effective (although I don't discuss this in the paper).
9. No one has really tried to disseminate these widely. Therefore promising strategies for EA are: digital public health campaigns for happiness/mental health; setting up new charities in the developing world to deliver in-person therapy and drugs ("AMF for Prozac" H/T Rob Wiblin); lobbying developed world governments to do stuff.
10. Once you revise the $/DALY cost-effectiveness figures to take into account how DALYs underrates happiness, it's possible treatments for depression at around $1000/DALY (such as by Stronger Minds) are in roughly the same ball park as AMF, which is $100/DALY (this gets confusing when you account for the badness of death). Given that mental health treatment is new compared to physical health treatments, there is good reason to be optimistic that our mental health treatments will get much more effective in the future.
11. I discuss some of the objections. Most relevant: if you already think X-risk is the biggest problem, my argument probably won't bite. If you support AMF or Give Directly, I think you should reconsider those and join me. If you support animal welfare you may want to reconsider depending on how cost-effective you think animal interventions are at present.
Feedback and thoughts would be very welcome. Because of I think human happiness is neglected I've working on a happiness app, Hippo, that I'd also be delighted to talk to people about (note: you might think this makes my above argument biased, or you might think is me trying to be consistent. Up to you)
*I'd like to credit Konstantin Sietzy, with whom I co-wrote an earlier version of the paper. I'd like to thank Hilary Greaves (my PhD supervisor), Michelle Hutchinson, John Halstead, Hauke Hillebrandt, James Snowden and probably other people I've now forgotten for their helpful comments.