Professor Dr. Francisco Paulo Jamil Almeida Marques, Professor Dr. Jakson Alves de Aquino, and Dr. Edna Miola have published Congressmen in the age of social network sites: Brazilian representatives and Twitter use, First Monday, 19(5) (2014).
Here is the abstract:
This paper investigates the factors that influence how members of the Brazilian House of Representatives adopt Twitter as part of their political communication strategy. Our intention is to understand the main variables that lead legislators to invest time and resources in microblogging. This quantitative study examined all of the 457 official congressional accounts registered on Twitter. These accounts were monitored weekly between February 2012 and February 2013. After empirically exploring the data, this work reflects on the results thanks in part to an examination of the literature on the intersection of the Internet and politics. The results indicate correlations between the use of Twitter and attributes like age and occupation of leadership positions.