Medication adherence in psychiatric patients is a major medical concern. Medication adherence in mood disorders is often problematic, with serious consequences ranging from chronicity to suicide. We explored the medication adherence in a sample of psychiatric inpatients, aiming to know wether there are differences between two types of depression [major depression disorder (MDD) and major depression with psychotic features (MDP)], and if medication adherence is associated with cognitive functioning.

We collected consecutively a sample of 30 women from a psychiatric inpatient unit (mean age = 44.37 ± 8.54, mean education= 12.27 ± 4.57), including 15 with MDD and 15 with MDP. Adherence, visual perceptual ability and memory, general cognitive functioning, phonemic and semantic fluency, executive functioning, verbal functioning, and simulation were assessed by Reported Adherence to Medication Scale, Rey-Osterrieth Complex Figure Test, Mini-Mental State Examination, phonemic fluency test (letter “R”), semantic fluency test (category “professions”), Trail making test, vocabulary from Wechsler Adult intelligence scale-III and Rey 15-item test, respectively.

All depressed patients displayed low scores in cognitive functioning, adhere moderately to medication, and did not simulated. The two groups differed statistically in all the neuropsychological and adherence measures. Medication adherence was strongly linked to all the neuropsychological measures, specially memory (r = 0.82, p < 0.001) and phonemic fluency (r = 0.82, p < 0.001).

This study suggest that cognitive functioning may be an important factor in medication adherence in depressive inpatients, with implications for an appropriate assessment of cognitive functioning and cautious psychoeducation of these patients.