A meta-analysis of craving studies in schizophrenia spectrum disorders

DSM-5 Substance Use Disorders (SUD) are frequent and debilitating comorbidities displayed by patients with schizophrenia spectrum disorders (SZ). One crucial feature of SUD is drug craving, an intense desire to consume a substance, commonly divided into reward and relief dimensions. Here, we conducted a meta-analysis of studies investigating craving in individuals with both SUD and SZ in order to examine whether these patients exhibit a distinct pattern of craving as compared to patients with SUD without SZ.

Meta-analysis based on the PRISMA guidelines.

Sixteen relevant publications were identified by a systematic search of databases, which included 1219 individuals (589 SUD-SZ and 630 SUD-without-SZ). Of the 16 studies, 11 focused on tobacco, 3 on cannabis and 2 on cocaine. When considered across all studies, SUD-SZ had significantly higher scores than SUD-without-SZ for global craving with medium effect size (k_{number of studies} = 16, Zr = 0.20 [0.15, 0.26], equivalent d = 0.41, P < 0.001). Discrete patterns emerged for reward (k = 7, Zr = 0.10 [0.02, 0.17], equivalent d = 0.20, P < 0.05) and relief (k = 7, Zr = 0.25 [0.17, 0.33], d = 0.52, P < 0.001) craving, and the direct comparison revealed a significantly greater effect for relief than reward (χ²(1) = 7.40 P = 0.007).

These results suggest that SUD-SZ cases experience higher craving, more specifically for relief, in comparison to patients with SUD-without-SZ. These clinical findings can foster the development of tailored addiction therapies for this specific comorbid population.