Based on the title of the article, I would say it is a cross-sectional study. This type of study looks at prevalence, frequency and/or distribution of a particular variable in a population.
From article //The aim of the present study was to evaluate the prevalence and characteristics of pain experienced by bipolar depressed patients treated by psychiatrists in their regular clinical practice, and to identify possible factors associated with the presence of pain in these patients.//
//In the descriptive analysis, the absolute frequency, mean, median and the dispersion measurements were calculated for the qualitative and quantitative variables. The prevalence (± 95% CI) of pain was calculated, and the crude and adjusted odds ratios (ORs) were used to analyze the factors associated with pain.//
I would research the different types of epidemiological studies to draw your own conclusion. Correlation studies in this field typically deal with populations, rather than individuals (as you have here).