Group revenues were down by 4.1% to £500.5m and group ad revenues were down by 1.4% to £285.7m.
The company's adjusted results, which exclude the writedown, show its pre-tax profits were up 7.4% to £98.2m and revenues were down 0.4% to £526.3m.
The company said it remains confident that its business reorganisation, the strength of its portfolio and its success at building and acquiring digital assets will all contribute to growth as the current cyclical advertising downturn comes to an end.
Its national newspaper division, which includes the Daily Mirror, experienced a 2.3% drop in ad revenues and a 16.7% increase in digital revenues to £1.4m.
The regional newspaper division earned ad revenues of £198.1m, down 1.4%.
Sly Bailey, chief executive of Trinity Mirror, said: "I am pleased to be able to announce a return to profit growth in the first half of the year. This is due to a combination of improving market conditions together with our continued focus on portfolio development and stringent cost control."
The company is still in the process of disposing of its sports division, which includes The Racing Post.