chronic or the family suffers other social risks. Our study, which focuses on Peru, provides much needed empirical evidence of the deleterious impact of maternal depression on child cognition in a region where the causal nexus between maternal depression and child cognition has not been studied before despite maternal depression prevalence rates that range between 35% and 50% (Wolf et al 2002).<sup>5</sup> Second, the paper focuses on an important marker of early cognition, the accumulation of vocabulary, which has been extensively shown to predict reading comprehension throughout school and into early adulthood (Powell and Diamond 2012). To capture vocabulary competence, we use performance in the Peabody Picture Vocabulary Test (PPVT), a test of receptive vocabulary, which has been widely used and translated to Spanish and Quechua, the two most widely spoken languages in Peru.<sup>6</sup> Finally, this paper contributes to the literature on the protective effect that other household members can have on the development of children exposed to maternal depression. Our results suggest that, in and of itself, the presence of other household members does not attenuate the effect of maternal depression on child vocabulary development. In fact, the presence of heavydrinking partners appears to worsen the effect of maternal depression. This latter result may be explained by the increased risk of Intimate Partner Violence (IPV) associated high alcohol consumption. Evidence from Psychology suggests IPV constitutes a major predictor of posttraumatic stress disorder in abused women (Pico-Alfonso, 2005) and can lead to negative interactions between mothers and children (Taylor et al, 2009), directly affecting child development (Bedoya et al, 2020). Using YL data, Bedoya et al (2020) find that IPV is one of the

> 5 In Peru, official statistics show a challenging scenario in terms of mental health in general. Data indicate that Mental, Neurological and Substance Abuse Disorders (MNS) are the leading cause of disease burden in the country, accounting for 17.5 percent of the total disease burden and for an average of 33.5 Disability-Adjusted Life Years for every 1,000 inhabitants (MINSA, 2018). Moreover, the severity of these effects tends to be worse among economically impoverished groups. Specifically, the annual prevalence of mental disorders among poor people is estimated to be up to 41.8 percent, twice as high as that of non-poor individuals (15.8 percent). The cost of inaction due to MNS is estimated at 1.45 percent of GDP in Peru (Bloom et al, 2011). Costs are higher when mid- to longterm effects of MNS are considered.

> 6 Using the National Longitudinal Survey of Youth in the United States, Frank and Meara (2009) do not find evidence that maternal symptoms of depression affect contemporaneous cognitive scores in school-aged children, as measured by the Peabody Individual Achievement Test in Math and Reading Comprehension, either. Along the lines of Surkan et al.’s (2012) argument for nutritional studies, it is possible that the heterogeneity of results across studies is the result of differences in measurements of both cognitive development and maternal depression, length of follow-up, sample characteristics, and sample sizes across studies, as well as varying level of social resources, caregiving norms, and both level of cognition, as well as prevalence of maternal depression in the populations under study.

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