Depressive illness in Parkinson's disease--indication of a more advanced and widespread neurodegenerative process?

The aims were to study if the type and complexity of Parkinsonian symptoms, as well as treatment, could be related to the occurrence and severity of later depressive symptoms. Furthermore, the aim was to study if there is a different depressive symptomatology in Parkinson's disease (PD) patients compared with depressive illness in an age-matched group of patients with major depression but without Parkinson's disease.

Eleven PD-patients with major depression (MD) were compared to 14 PD-patients without depression and to 12 MD patients without PD.

PD patients who later developed a depressive illness were younger at the debut of PD than patients without depression (P < 0.05). At inclusion the depressed PD patients were more disabled than PD patients without depression with higher level in the H&Y scale (P<0.05), and they had more involuntary movements according to Unified Parkinson's Disease Rating Scale (UPDRS IV) (P < 0.01). A family history of depression was found in one third of the depressed non-parkinsonian patients but in none of the PD groups. Sleep disturbances were significantly more common among depressed PD patients than in PD patients without depression but even more common in depressed patients without PD.

Depressed PD patients had a longer duration of PD and more severe motor symptoms than PD patients without depression, although tremor as an initial symptom seemed to be more common in PD without a later depression. It cannot be excluded that depression in PD reflects a more advanced and widespread neurodegeneration, including serotonergic as well as dopaminergic neurons. Sleep disturbances is common and could be overlooked as an expression of depression.