* Confidence index falls to 117.9 in January
* Gauge still remains above historical average
SAO PAULO, Jan 24 (Reuters) - Consumer confidence in Brazil fell in January for the fourth month in a row as sentiment about current economic conditions worsened to the lowest level since May 2010, a private survey showed on Thursday.
Brazilian think tank Fundação Getúlio Vargas (FGV) said its consumer confidence index fell to a reading of 117.9 in January from 118.7 in the previous month.
Despite the drop, the index remained above its historical average, FGV said in a report. Household consumption, supported by low unemployment and rising salaries, has been Brazil's main growth engine over the past decade.
The survey's barometer of the current economic situation dropped to a reading of 131.9 from 133.5 in December, while the gauge for the next six months slipped to a reading of 110.5 from 111.3, the lowest since February.
A reading of consumer sentiment about current economic conditions dropped to 98.0 from 102.4 in December.
FGV's consumer confidence survey is based on interviews conducted with over 2,000 people in seven large Brazilian cities between Jan. 2 and Jan. 21.