To address the societal challenges posed by depression, we need to know more about the etiological factors and long-term effects of depression. A few studies have indicated that depression may have long-term effects on cognitive abilities and neuropsychological function, such as memory and processing speed. If this is the case, depression could also affect the quality of life and work capacity of formerly depressed individuals in remission.

We are conducting a 23-year follow-up study of a cohort of depressed, formerly depressed, and never depressed individuals to investigate neuropsychological vulnerability factors and consequences related to the development and relapse of depression. Neuropsychological tests such as WAIS-III (i.e., IQ test), CVLT-II (i.e., verbal memory), D-KEFS (i.e., processing speed), and others are used to obtain a broader picture of the cognitive and emotional function of the participants. The study originated at the Department of Psychology, UiT - The Arctic University of Norway, in 1997 (T1) and the first follow-up study (T2) was conducted in 2006-2007. Many participants are now retirees. The results of the study have indicated several cognitive vulnerability factors that may serve as markers for future or recurrent depression. There have been 19 peer-reviewed articles published from the first two studies, which provide much insight into processes and factors that influence and are influenced by depression.

By conducting a second follow-up study (T3), 23 years after the initial data collection, we can examine how neuropsychological factors relate to the risk of relapse and first onset as well as variation in depressive states over three measurement points, and factors that affect cognitive decline and dementia in aging. The study offers a unique opportunity to examine long-term correlations, as these factors have not previously been studied in such a large sample, followed over a comparable period, with three waves of data collection.

In 2021, we started a second follow-up study (T3) with a primary focus on neuropsychological function, childhood trauma, and metacognition. We also hope this time to achieve high participation from individuals who took part at T1 and T2. A PhD candidate is attached to the project.

The project has several local and national collaborators.