Co-Morbidity between Major Depression and Schizophrenia: Prevalence and Clinical Characteristics

The aim of this study was to explore the co-morbidity between Major Depressive Disorder (MDD) and Schizophrenia (SZ) among a large number of patients describing their clinical characteristics and rate of prevalence.

A cohort-study was carried out on 396 patients affected by MDD and SZ who consecutively attended the Department of Psychiatry, Rumeilah Hospital in Qatar. We employed the World Health Organization - Composite International Diagnostic Interview (WHO-CIDI) and the Structured Clinical Interview for DSM-5 (SCID-5) for diagnoses. Patients were also grouped in MDD patients with and without co-morbid SZ (MDD vs MDD/SZ) for comparisons.

A total of 396 subjects were interviewed. MDD patients with comorbid SZ (146(36.8%)) were 42.69±14.33 years old whereas MDD without SZ patients (250 (63.2%)) aged 41.59±13.59. Statistically significant differences between MDD with SZ patients and MDD without SZ patients were: higher BMI (Body Mass Index) (p=0.025), lower family income (p=0.004), higher rate of cigarette smoking (p<0.001), and higher level of consanguinity (p=0.023). Also, statistically significant differences were found in General Health Score (p=0.017), Clinical Global Impression-BD Score (p=0.042), duration of illnesses (p=0.003), and Global Assessment of Functioning (p=0.012). Rates of anxiety dimensions (e.g.: general anxiety, agoraphobia, somatisation, etc.), mood dimensions (e.g.: major depression, mania, oppositional defiant behaviour, Bipolar disorder), Attention Deficit Hyperactivity Disorder, psychotic and personality dimensions were higher among MDD with SZ patients than MDD without SZ.

This study confirms that MDD with SZ is a common comorbidity especially among patients reporting higher level of consanguinity. MDD/SZ comorbidity presents unfavourable clinical characteristics and higher levels of morbidity at rating scales.