I did some further investigation into the relationship between interest in politics and happiness and found that the GSS included another question on interest in politics in 1987: "How interested are you in politics and national affairs?" If you take the four samples with interest and happiness variables (1987, 1990, 1996, and 2014) and control for income, education, age, gender, race, and marital status, more political interest is associated with more happiness: the t-ratio is 3.3 and the estimated effect of increasing interest from the lowest to highest level is about the same as the estimated effect of increasing income by a factor of 4.*
However, the piece by Arthur Brooks that I discussed in my last post seemed to be talking about the effects of excessive interest in politics--"hitting your twitter feed fifty times a day." So maybe it's a non-linear relationship, with moderately interested people happier than people at the extremes? No--it's pretty much linear in the combined sample.
I proposed that the relationship differed in 2014 than in 1990 and 1996. On looking closely, it seemed to be the position of people who said they were "very interested" that changed. More precisely, here are estimates of where the "very interested" are relative to the linear trend (positive numbers mean happier than predicted):
1987 .024 .038
1990 .097 .056
1996 .156 .051
2014 -.124 .048
Given the standard errors, it's not possible to be confident about whether there were any differences among 1987, 1990, and 1996, but 2014 is almost certainly different from at least 1990 and 1996. It seems reasonable that people who are highly interested in politics will be affected by how things are going in politics, so I think this supports the interpretation in my previous post: the relationship depends on the nature of politics at the time. Or if you want it in the form of eternal wisdom, attaching yourself to external things can bring either happiness or misery, depending on the quality of those external things.
*Brooks also controlled for self-rated political ideology. I'm not sure that you should, so I left it out, but whether you include it or not doesn't make much difference.