(CNN) – New research found a connection between repetitive head impacts and depression, leading to worse cognitive function later in life.

A study published in the Journal Neurology found that as trauma increased so did depressive symptoms.

Tests of memory, learning, processing speed and reaction time also revealed a similar pattern between head trauma and worse cognitive function later in life.

One of the study leads says this doesn’t mean all people with repetitive hits to the head will develop later-life problems with cognitive functioning and depression. But it proves that exposure plays an important role in the development of these problems.

The study was limited as researchers pointed out they did not know the degree of repetitive impacts or the frequency of traumatic brain injuries in participants.