This study examined the potential of using the regular administration of a common neuropsychological test, the CVLT-II, to assess learning potential in schizophrenia. Based on List A trial 1 performance and the learning slope, a schizophrenia sample was divided into three learning potential groups (non-learners, learners and high-achievers) that differed in the use of learning strategies. High-achievers utilized more semantic clustering than learners and non-learners, and non-learners were less consistent in words recalled than the other two groups. This standard administration approach is a promising, time-saving alternative to the modified tests of learning potential used so far.
Evidence of associations between neurocognitive function and cannabis use in schizophrenia is inconclusive. However, direct measures of cannabis intake and premorbid function are rarely explored in this context. We investigated the relation between cannabis use, determined by its presence in urine, and neurocognitive functioning in schizophrenia controlling for the potential bias of premorbid functioning.
Naturalistic study of 364 patients with schizophrenia spectrum disorder from catchment areas in Oslo, Norway. Hierarchical multiple regression analyses were used to assess the relationship between cannabis in urine and measures of neurocognitive functioning, with adjustment for confounders, including premorbid functioning.
Cannabis was detected in the urine of 21 patients, who had significant dysfunction in several neurocognitive domains independent of a current diagnosis of cannabis abuse. However, level of premorbid functioning explained the associations for all measures.
Differences in premorbid functioning may explain apparent differences in neurocognitive function between schizophrenia spectrum patients using cannabis or not. The findings suggest that illness-related traits present early in life can affect both later cannabis use and neurocognition, probably by complex mechanisms.
The gene encoding Catechol O-methyltransferase (COMT), a dopamine catabolic enzyme, is an important candidate gene in several psychiatric disorders. Several studies have shown an association between the functional Val(158)Met polymorphism and cognitive performance. However, the results have been inconsistent and there are few studies addressing other COMT single nucleotide polymorphisms (SNPs).
We investigated SNPs across the whole COMT gene, including the Val(158)Met polymorphism, for a putative effect on working memory, executive function and IQ in 315 patients with schizophrenia or bipolar disorder and 340 healthy controls.
We replicated the association between the Val(158)Met variant and working memory performance, and found a significant interaction between this SNP and diagnosis, with patients with schizophrenia showing a specific, reduced performance on the 2-back test. Several other COMT SNPs were associated with different cognitive functions, but did not remain significant after controlling for multiple testing. We also found significant interaction effects between the SNP variants and gender.
The present study replicates earlier findings showing an association between the functional Val(158)Met polymorphism and working memory performance, with schizophrenia subjects particularly vulnerable. Furthermore, our findings suggest that other parts of the COMT gene seem to affect several related cognitive domains, which further support the notion that COMT is a modifier gene in prefrontal dopamine functioning.
The results of investigations on the cognitive outcomes of adolescents exposed prenatally to radiation from Chernobyl are inconsistent. In 2005 through 2006, we assessed individuals exposed prenatally (N = 84) and controls (N = 94) using a broad neuropsychological test battery. Neuropsychological performance was significantly weaker in the 84 adolescents exposed prenatally compared to the 94 controls on measures of verbal working memory, verbal memory, and executive functioning when controlling for possible confounders. Our findings add new and important support to the hypothesis that the Chernobyl accident had a specific effect on the neuropsychological functioning of those exposed prenatally.
BACKGROUND: We have studied the significance of the thyroxine treatment for neuropsychological functioning in young adults with congenital hypothyroidism. SUBJECTS AND METHODS: This is a neuropsychological follow-up study of a three-year cohort of early treated congenital hypothyroidism in Norway (N = 49) at age 20. Siblings comprise the control group (N = 41, 21 years). RESULTS: The patient group performed weaker than the control group on cognitive and motor measures. They reported somewhat more psychosocial problems; fewer completed high school. A more severe hypothyroidism at the time of diagnosis was associated with a larger motor deficit at age 20. Better cognitive function in young adulthood was associated with a higher thyroxine starting dose and serum thyroxine level in the first years of life. Blood samples in young adulthood showed elevated thyrotropin levels in 45% of the patients. INTERPRETATION: This study supports the new guidelines for treatment of congenital hypothyroidism with a higher starting dose of 10-15 microg thyroxine/kg/24 hours. The young adults are in need of better medical follow up.
OBJECTIVE: To describe intellectual, motor, and school-associated outcome in young adults with early treated congenital hypothyroidism (CH) and to study the association between long-term outcome and CH variables acting at different points in time during early development (CH severity and early L-thyroxine treatment levels [0-6 years]). METHODS: Neuropsychological tests were administered to all 49 subjects with CH identified during the first 3 years of the Norwegian neonatal screening program (1979-1981) at a mean age of 20 years and to 41 sibling control subjects (mean age: 21 years). RESULTS: The CH group attained significantly lower scores than control subjects on intellectual, motor, and school-associated tests (total IQ: 102.4 [standard deviation: 13] vs 111.4 [standard deviation: 13]). Twelve (24%) of the 49 CH subjects had not completed senior high school, in contrast to 6% of the control subjects. CH severity (pretreatment serum thyroxine [T4]) correlated primarily with motor tests, whereas early L-thyroxine treatment levels were related to verbal IQ and school-associated tests. In multiple regression analysis, initial L-thyroxine dose (beta = 0.32) and mean serum T4 level during the second year (beta = 0.48) predicted Verbal IQ, whereas mean serum T4 level during the second year (beta = 0.44) predicted Arithmetic. CONCLUSIONS: Long-term outcome revealed enduring cognitive and motor deficits in young adults with CH relative to control subjects. Verbal functions and Arithmetic were associated with L-thyroxine treatment variables, suggesting that more optimal treatment might be possible. Motor outcome was associated with CH severity, indicating a prenatal effect.
Previous studies investigating subclinical signs of cognitive decline in presymptomatic carriers of Huntington's disease (HD) have shown conflicting results. The current study examines cognition in 105 at-risk individuals, using a broad neuropsychological test battery and adopting strict inclusion criteria for attaining a homogeneous sample. Results obtained by analyses of variance and effect size calculations indicate no clinical evidence of significant cognitive decline in asymptomatic HD carriers very far from onset of illness compared to noncarriers. Closeness to disease onset amongst gene carriers influenced cognition negatively whereas cytosine-adenine-guanine (CAG) repeat size did not. The findings call for longitudinal follow-up studies using a combination of clinical instruments and experimental paradigms to pinpoint when subtle cognitive deficits occur and within which of the cognitive domains.
The aim of the study was to investigate which factors are associated with age at onset in bipolar disorder with a specific focus on excessive alcohol and cannabis use, and the sequence of the onsets of excessive substance use and bipolar disorder. We investigated a naturalistic sample of 151 patients with bipolar I and II disorder receiving psychiatric treatment. Whether the presence of excessive substance use prior to bipolar disorder onset or the type of substance used (alcohol or cannabis) was associated with differences in age at onset was investigated using hierarchical and multiple linear regression analyses, adjusting for potential confounders. Patients with excessive alcohol use had a significantly later onset compared with patients with excessive cannabis use. Excessive general substance use prior to bipolar disorder onset was associated with a later onset. However, excessive cannabis use was associated with an earlier onset whether it preceded or followed bipolar disorder onset, also after adjusting for possible confounders. Excessive use of alcohol or other substances was not independently associated with age at onset in multivariate analyses. Alcohol use was associated with a later onset compared with cannabis use, suggesting different relationships to the onset of bipolar disorder. Lifetime use of cannabis predicted an earlier onset, independent of the sequence of onsets. This indicates that an early onset may increase the risk of cannabis use and that cannabis use may trigger bipolar disorder in vulnerable individuals.
Cites: Am J Psychiatry. 2006 Sep;163(9):1633-616946191
BACKGROUND: There is a strong association between bipolar disorder (BD) and substance use disorder (SUD). The clinical and functional correlates of SUD in BD are still unclear and little is known about the role of excessive substance use that does not meet SUD criteria. Thus, the aims of the current study were to investigate lifetime rates of illicit substance use in BD relative to the normal population and if there are differences in clinical and functional features between BD patients with and without excessive substance use. METHODS: 125 consecutively recruited BD in- and outpatients from the Oslo University Hospitals and 327 persons randomly drawn from the population in Oslo, Norway participated. Clinical and functional variables were assessed. Excessive substance use was defined as DSM-IV SUD and/or excessive use according to predefined criteria. RESULTS: The rate of lifetime illicit substance use was significantly higher among patients compared to the reference population (OR = 3.03, CI = 1.9-4.8, p
Major depression is associated with impairment of cognitive functions, and especially higher-order cognitive processes referred to as executive functions (EF). Whether this is a general finding is unclear. Patients without EF impairment may have different treatment needs than patients with EF impairment, and will probably have a better everyday functioning. Thus, it is important to identify the prevalence and characteristics of depressed patients without EF impairment. Forty-three patients with recurrent major depressive disorder (19-51 years) and 50 healthy controls were included in the study. The subjects were assessed with neuropsychological tests selected to measure central areas of EF, and screened on clinical and demographic variables. Within the depressed group, a total of 56% were defined as EF unimpaired. These patients were characterised by higher intellectual abilities and fewer depression episodes than the subgroup of patients with EF impairment. The subgroups were similar in age at debut of illness, severity of depression, general psychopathology and global level of functioning. In conclusion, about half of patients with recurrent major depression have normal EF. Since cognitive impairment and depressive symptomatology seem to be distinct dimensions, a neuropsychological investigation could help to ensure optimal treatment in patients with recurrent major depression.