Meta-analysis of neurocognitive deficits in unaffected relatives of obsessive-compulsive disorder (OCD): comparison with healthy controls and patients with OCD

Background Obsessive-compulsive disorder (OCD) has been associated with cognitive deficits, particularly with executive functions. These findings support fronto-striatal dysfunction in OCD. However, it is not certain whether these findings are trait features of OCD. In recent years, a number of studies have investigated cognitive functions in unaffected relatives of OCD (OCDrel) but the findings of these studies are contradictory. Methods A systematic review in Pubmed and Scopus databases was performed until 18 March 2019, to locate the studies comparing cognitive functions of OCDrel with healthy controls and OCD patients (OCDpt). A random-effects meta-analysis was conducted. Results Current meta-analysis included 16 studies including 527 OCDrel, 445 OCDpt and 639 healthy controls. Healthy controls overperformed OCDpt in all cognitive domains (d= 0.36-0.86). OCDrel underperformed healthy controls in inhibition (d= 0.58, CI = 0.29-0.86), planning (d= 0.45, CI = 0.28-0.63), decision-making (d= 0.58, CI = 0.19-0.98). OCDrel also had small-sized deficits in set-shifting (d= 0.37, CI = 0.04-0.69) and visual memory (d= 0.28, CI = 0.08-0.49). OCDpt underperformed OCDrel in visual memory (d= 0.45, CI = 0.22-0.67) and set-shifting (d= 0.23, CI = 0.04-0.42). Conclusions Current findings suggest that abnormalities in inhibition, planning/problem solving and reward-based decision-making are shared features of OCDrel and OCDpt and might be trait markers related to vulnerability for developing OCD. Visual memory and set-shifting deficits might potentially be biomarkers of incipient illness or subthreshold OCD presentation among OCDrel. Further exploration of cognitive heterogeneity in OCDrel and investigating the effects of the subtypes of OCD in probands on cognitive impairment in OCDrel are needed.