Depression Associated Disorders: Comorbidity, eurobiological and eurobehavioural Link

Abstract

Comorbidity commonly refers to the co-occurrence (or dual diagnosis) of two disorders or syndromes in the same patient, regardless of whether the disorders are coincidentally or causally linked. Indeed, illnesses have been classified in discrete diagnostic categories although no sharp discontinuities in symptom distributions are observed across most mental disorders. Depression is a relatively common psychiatric comorbididy of most neurological disorders, with prevalence rates ranging between 20 and 50% among patients with stroke, multiple sclerosis, epilepsy, Parkinson’s disease and dementia. Furthermore, depression is an independent predictor of poor quality of life in these patients and has a negative impact on the response to treatment, course and recovery of neurological deficits. Comorbid depressive disorders in neurologic patients can be indistinguishable to the primary mood disorders and may mimic major depression, dysthymic, minor depressive, and bipolar disorders described in the DSM-IV classification of mood disorders. In addition, the great overlap of medical and psychiatric symptoms in depression and neurologic disorders may lead to both false-positive and false-negative diagnoses of depression. Patient with comorbid condition have lower response rate and /or a longer time to response, greater reports of side effect early in treatment and greater likely hood of dropping out. In this review, we focus on comorbid disorder associated with depression.