Subthreshold depression and subjective cognitive complaints in Parkinson's disease

Background and purposeSubthreshold depression (SubD) is characterized by clinically relevant depressive symptoms not meeting criteria for major depression. The possible association of SubD with subjective cognitive complaints and/or objective cognitive impairments was investigated in a sample of consecutive, non-demented Parkinson's disease (PD) outpatients. MethodsAmongst 115 patients, SubD was identified in 30 patients, major depression in 33; 36 patients were classified as non-depressed. Enrolled patients were administered tests and questionnaires validated in PD for assessing objective and subjective cognitive dysfunctions. ResultsOn objective cognitive measures SubD patients did not differ from non-depressed patients, whereas depressed patients achieved significantly lower scores than the other two groups. SubD and depressed patients reported more cognitive complaints than non-depressed patients. ConclusionsSubD is a non-motor aspect of PD that is not related to objective cognitive deficits but is associated with subjective cognitive complaints, thus impacting on patients' well-being.