Its been a long time since I took statistics courses, but aren't those r values rather low to conclude anything?

"Increased SFV use was associated with poorer cognition (moderate mean effect size, r = −.34), with attention (r = −.38) and inhibitory control (r = −.41) yielding the strongest associations. Similarly, increased SFV use was associated with poorer mental health (weak mean effect size, r = −.21), with stress (r = −.34) and anxiety (r = −.33)"