The Danish PET/depression project: cognitive function and regional cerebral blood flow.

OBJECTIVE: To clarify the relationship between cognitive functions and regional cerebral blood flow (rCBF) in a large group of depressed patients compared with healthy controls. METHOD: A set of principal components was extracted from scores of a battery of neuropsychological tests of 40 patients suffering from major depression and 49 healthy controls. The components were correlated by multiple linear regression analyses to selected regions of interest in the brain obtained from positron emission tomography images. RESULTS: In contrast to findings in the healthy controls, cognitive functions in the depressed patients correlated significantly with rCBF in specified regions of interest in only a few instances. CONCLUSION: Our study indicates that disturbed cognitive functions in depression do not relate to specific areas of the brain in the same way as normal cognitive functioning, suggesting that the abnormalities of brain function in major depression may be qualitative, rather than quantitative, in nature.

The Danish PET/depression project: clinical symptoms and cerebral blood flow. A regions-of-interest analysis.

OBJECTIVE: We wanted to explore associations between clinical symptoms of depression and the blood flow to specific regions of the brain. Furthermore, we wanted to compare the regions-of-interest (ROI) method with the functions-of-interest (FOI) approach. METHOD: The resting blood flow to 42 ROI in the brain was obtained with positron emission tomography (PET) imaging in 42 representative in-patients with major depression and 47 matched healthy controls. RESULTS: The patients had increased blood flow to hippocampus, cerebellum, anterior cingulate gyrus, and the basal ganglia. A strong negative correlation was found between the degree of psychomotor retardation of the patients and the blood flow to the dorsolateral and supraorbital prefrontal cortices. The total Hamilton score was correlated with the blood flow to the hippocampus. CONCLUSION: Our findings support the notion that depressed patients have disturbances in the loops connecting the frontal lobes, limbic system, basal ganglia, and cerebellum.

The Danish PET/depression project: PET findings in patients with major depression.

BACKGROUND: It is hypothesized from previous positron emission tomography (PET) studies of patients with major depression that dysfunction of regions of the limbic system and the frontal lobes in close connection with the basal ganglia is involved in the pathophysiology of major depression. METHODS: By means of PET and 15O labelled radioactive water we determined an index of the neuronal activity by mapping the cerebral blood flow distribution of 42 unselected in-patients suffering from moderate to severe depression and 47 healthy controls controlling for age and gender. The PET maps were co-registered to magnetic resonance images of the anatomy of the brain. RESULTS: The functions-of-interest analysis revealed significant gender differences in cerebral blood flow and changes in the relative distribution of the blood with increasing age. The patients had increased activity of the hippocampus and the cerebellum compared to the healthy controls when corrected for these confounders and the influence of antidepressant medication. Furthermore, data in the Danish Psychiatric Central Register showed that the patients studied were representative of the population of depressed patients admitted to the hospital during the study period. CONCLUSION: Our main finding is increased blood flow to the hippocampus, even when controlling for a number of confounders. This is in accordance with a rapidly expanding literature suggesting an important role for this structure in major depression.

Structural brain abnormalities in unselected in-patients with major depression.

OBJECTIVE: Several studies have indicated an increased frequency of cerebral atrophy and white matter lesions in patients with major depression, especially in older age groups. METHOD: Forty-four representative in-patients with major depression in which neurological disorders were clinically excluded, and 49 age- and gender-matched controls were MR scanned. RESULTS: Unexpectedly, two of the patients had severe brain pathology which could account for their psychiatric symptoms. Analysis of the remaining patients (mean age 42 years) did not reveal an increased frequency of cerebral atrophy. The number of white matter lesions increased with age to an odds ratio greater than 3 for patients aged 50, but this was not statistically significant. CONCLUSION: Brain atrophy and white matter lesions did not occur with significantly increased frequency in these relatively young unselected depressives, but the finding of severe brain pathology stresses the importance of brain imaging in late-onset psychiatric disorders.

Psychoactive substance use diagnoses among psychiatric in-patients.

OBJECTIVE: To estimate the prevalence and possible under-diagnosing of substance use disorders and to consider factors that might influence diagnosing of substance use disorders. METHOD: Data collected from case records and PSE interviews of psychiatric in-patients from 12 psychiatric departments in Denmark admitted during October 1996 were compared with data from the Danish Psychiatric Register. RESULTS: A substantially lower prevalence of substance use diagnoses were found in the register (26.1%) than in the research data (50.0%). A high prevalence of co-occurrence between substance use disorders and mental disorders other than substance use disorders was found (37.3%). In the majority of cases knowledge of the substance use disorders was present in the case records, although they had not resulted in a diagnosis. CONCLUSION: The under-diagnosis of substance use disorders is due not only to concealed diagnostic signs and symptoms but also to an under-diagnosis by the psychiatrists, in spite of the fact that information on the substance use was accessible.