Obsessive compulsive disorder Motor inhibition ability

A number of studies have used Go/Nogo paradigms to assess motor inhibition ability in OCD individuals; results are inconsistent. Bannon, Gonsalvez, Croft and Boyce (2002; 2006) conducted two studies comparing OCD patients and individuals suffering from Panic disorder and found that the former performed more commission errors than the latter. Furthermore, a subgroup of remitted OCD patients were administered the same Go/Nogo task 1.40 (SD = 0.52) years after the end of treatment; no difference between the two performances (symptomatic vs remitted phase) emerged, thus suggesting the trait-like nature of motor inhibition symptoms in OCD (Bannon et al., 2006). Two further studies (Bottesi, Ghisi, Sica, & Sanavio, 2012a; Penadés et al., 2007) proved that OCD patients performed more commission errors than healthy controls in a Go/Nogo task. Recently, Abramovitch, Dar, Schweiger and Hermesh (2011a) reported that OCD patients performed slower RTs than healthy controls on a different typology of Go/Nogo task, namely the Expanded Go-Nogo test. Furthermore, the same Authors compared OCD patients, individuals with attention deficit/hyperactivity disorder (ADHD) and healthy controls in the same Go/Nogo task and found that OCD and ADHD patients performed more commission errors that healthy controls, whereas they did not differ each other (Abramovitch, Dar, Hermesh, & Schweiger, 2011b). On the other hand, Johannes et al. (2001) and Bohne et al. (2008) compared OCD patients with individuals suffering from Tourette syndrome and healthy controls on one hand, and patients with Trichotillomania and healthy individuals on the other one; no differences between OCD patients and healthy controls in the behavioural performance emerged from both studies. Many other studies failed in detecting

behavioural differences between OCD patients and healthy controls (Hermann, Jacob, Unterecker, & Fallgatter, 2003; Kim, Kim, Yoo, & Kwon, 2007; Maltby, Tolin, Worhunsky, O’Keefe, & Kiehl, 2005; Ruchsow et al., 2005; 2007); nonetheless, anomalies in the event-related potentials (ERP) components usually related to commission errors (ERN/Ne, N200, P300; Hermann et al., 2003; Kim et al., 2007; Ruchsow et al., 2005; 2007) and hyperactive anterior cingulated cortex (ACC) during task execution (Hermann et al., 2003; Maltby et al., 2005) were observed in OCD groups.

Studies using the Stop-Signal task generally agreed in finding impaired inhibitory control in OCD patients. Penadés et al. (2007) observed slower SSRTs in OCD patients than healthy controls; Chamberlain, Fineberg, Blackwell, Robbins and Sahakian (2006) reported that OCD individuals’ performance was similar to that of patients with Trichotillomania, and both clinical groups were significantly more impaired than healthy participants. Chamberlain et al. (2007) reported that unaffected first-degree relatives of OCD patients and OCD probands did not differ significantly in the performance at the Stop-Signal task; in addition, both groups showed significantly longer SSRTs than comparison subjects without a known family history of OCD. Boisseau et al. (2012) compared OCD patients, individuals with Eating disorders and healthy controls: those with OCD were characterized by slower SSRTs than healthy individuals, and showed more omission errors than those suffering from Eating disorders.

Decision making ability

Mixed results emerged from studies investigating decision making ability through the IGT among OCD patients. Cavedini et al. (2002a) found that OCD patients selected a significantly higher number of cards from the disadvantageous decks than both healthy controls and patients with Panic disorder; furthermore, OCD individuals did not shift in card selection from disadvantageous to advantageous decks. Healthy controls and patients with Panic disorder did not differ neither in card selection nor in the adopted strategy (they both showed a learning effect over time). Within the OCD group, those characterized by a poor treatment response performed worse than those positively responding to treatment. A poorer performance in OCD patients (in terms of both total and partial net-scores and no shifting in card selection) compared to healthy controls was also found by Starcke, Tuschen-Caffier, Markowitsch and Brand (2009). A following study performed by the same Authors further highlighted more disadvantageous choices in OCD patients that in healthy participants; in particular, the OCD group was characterized by lower net-scores in blocks 3 and 5 (Starcke, Tuschen- Caffier, Markowitsch, & Brand, 2010). Lastly, a group of OCD patients overall performed significantly worse (less advantageous choices) than a group of healthy subjects (Cavedini, Zorzi, Piccinni, Cavallini, & Bellodi, 2010) and lower net-scores (total score and second fifth cards) were observed in a large sample of Brazilian OCD patients compared with healthy controls (da Rocha, Alvarenga, Malloy-Diniz, & Corrêa, 2011). A further support of decision making impairments characterizing OCD came from two studies using the IGT in unaffected first-degrees relatives of OCD patients (Cavedini et al., 2010; Viswanath, Janardhan Reddy, Kumar, Kandavel, & Chandrashekar, 2009): results highlighted that OCD relatives selected a higher number

of cards from disadvantageous decks than both healthy controls’ relatives (Cavedini et al., 2010; Viswanath et al., 2009) and healthy probands (Cavedini et al., 2010).

On the other hand, several authors did not find deficits in the IGT performance when assessing OCD patients. Nielen, Veltman, de Jong, Mulder and den Boer (2002) reported that individuals with OCD and healthy controls exhibited a similar performance, both shifting to the more advantageous decks over time. Also Lawrence et al. (2006) failed in detecting overall differences between OCD patients and healthy controls during the IGT. Nonetheless, they found that patients with higher hoarding symptomatology were characterized by a poorer performance. Lastly, Krishna et al. (2011) did not report any impairment in regards to decision making processes when comparing medication-naïve and never-treated OCD patients with matched healthy controls.

3.4.3. Alcohol dependence