Impairments in Cognition Across the Spectrum of Psychiatric Disorders: Evidence From a Swedish Conscript Cohort

It is well established that cognitive deficits are an almost invariable component of the schizophrenia syndrome. Much less is knownabout theassociation of cognitive deficits and the range of psychiatric disorders. The current study made use of a Swedish conscript cohort which included an IQassessment and full psychiatric evaluationat conscription of all 18- to 19-year-old males. It was found that reduced in-tellectual functioningwas found inassociationwithpsychosis and neurotic disorders including depression, personality dis-orders, alcoholism, anddrugdependence.The effectwas par-ticularly strong for alcoholism. This presumably represents a combination of premorbid deficits (as demonstrated in thosewho developed schizophrenia someyears later) plus co-incident impairments. The direction of causality of this latter association is likely to be both forwardand reverse.Different cognitive subtests showed varied strengths of association: ‘‘mechanical ability/knowledge,’ ’ which might reflect plan-ning and reasoning more than the other subtests, had the strongest effect. Cognitive deficits are widespread in psychi-atric disorders and should be taken into account in clinical interactions. Key words: IQ/psychosis/cognition/premorbi