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The happy, the sad, and the anhedonic

Towards understanding altered reward function from a micro-level perspective
PhD ceremony:dr. V.E. (Vera) Heininga
When:December 04, 2017
Supervisor:prof. dr. A.J. (Tineke) Oldehinkel
Co-supervisors:dr. E. Nederhof, dr. G.H. van Roekel
Where:Academy building RUG
Faculty:Medical Sciences / UMCG
The happy, the sad, and the anhedonic

The happy, the sad, and the anhedonic

If one cannot enjoy anything, is life still worth living? Being unable to enjoy things is a detrimental experience. In clinical practice, this is called anhedonia. Anhedonia is a core symptom of depression but not yet fully understood.

Single time questionnaires, brain research, and laboratory tests show that anhedonia is often accompanied by less positive feelings, less motivation and a lowered ability to adjust behavior based on what's enjoyable. However, how these impairments in reward-related functioning unfold outside the laboratory is largely unknown.

This dissertation is the first to reveal changes in reward-related functioning in the daily life of people with anhedonia. Through their smartphone, 138 people were asked several times a day about what they had done, how they felt, and what environment they were in. Subsequently, the people with anhedonia were compared to those without anhedonia in their pleasure experience, motivation and ability to learn from what's enjoyable from one time-point to the next (and thus at the micro level).

Many findings confirmed what was already known about anhedonia. On average, people with anhedonia felt less motivated and experienced less emotional emotions on average. However, new things were also discovered. For example, people with anhedonia appeared to be stuck in a kind of negative spiral, in which reduced pleasure reduced motivation and vice versa. In addition, people with anhedonia did not experience a loss of pleasure at all times. On average, they experience less pleasure, but their feelings of pleasure went more up and down.