[Contribution of biology to nosology of depressive states. Neurochemical, endocrine and genetic factors (author's transl)]

Genetic factors have been evidenced in the etiology of manic-depressive syndromes through twins, morbidity risk studies, linkage studies with genetic markers such as color blindness and the Xga blood group, as well as through adoption studies. Most genetic studies indicate that there is a genetic and biological heterogeneity in manic-depressive illness. Among these manic-depressive syndromes, one group is consistent with a dominant X-linked transmission of the disease. From the neurochemical point of view, most investigators emphasize the importance of cerebral neurotransmitter substances such as catecholamines and indolamines in the pathogenesis of bipolar depressive states. According with this hypothesis, depression is associated with a functional deficit in brain monoamines while mania may be due to an hyperproduction of monoamines. These neuropharmacological studies are of importance because they also have neuroendocrine implications. Some pituitary hormones are secreted under the control of brain monoamines, and they are also implicated in the pathogenesis of depressive states.

Thyrotrophin, prolactin and growth hormone responses to TRH in barbiturate coma and in depression

The effects of 200 microgram thyrotrophin-releasing hormone (TRH) i.v. on thyrotrophin (TSH), prolactin (PRL), growth hormone (GH) and triiodothyronine (T3) were studied in eight patients with barbiturate coma due to attempted suicide, in the same patients after recovery, in eight depressive patients and in eight normal controls. The patients with barbiturate coma presented normal basal TSH and PRL, elevated basal GH and normal PRL but blunted TSH responses to TRH; their GH concentrations varied widely without consistent relation to TRH administration. The same patients after recovery from coma presented normal TSH and PRL, slightly elevated basal GH, and normal PRL but blunted TSH responses to TRH; in four of these patients, a clear-cut rise in GH (i.e. more than 10 ng/ml) occurred after TRH administration. The depressive patients presented normal basal TSH and PRL, slightly elevated basal GH, and normal PRL but blunted TSH responses to TRH; in four of these patients, a moderated rise in GH (less than 10 ng/ml) occurred after TRH administration. The increment in T3 concentrations 120 min after TRH was found reduced in the comatose patients only. Basal cortisol was measured in all the subjects and found elevated in the comatose patients only. It is concluded that the abnormal TSH and GH responses to TRH observed in patients with barbiturate coma are more likely related to depressive illness than to an effect of barbiturates at the pituitary level. Barbiturates might affect thyroid secretion.

The age factor in depressive illness: some genetic considerations

The age of onset of depressive illness may have an association with the genetic character and clinical course of the disorder. There are several genetic models of depressive disorder that are based on differences in age of onset. According to a multifactorial model, for example, a late onset would indicate a smaller genetic and greater environmental component. A correlation has been found between positive family history of affective illness and early age of the first episode. The presence or absence of a family history of affective illness has also been found to be distinguished by pharmacology, physiology, symptomatology, and severity. It is therefore recommended, for purposes of treatment, that a family history be gathered on patients with depressive illness.

Plasma dopamine beta hydroxylase activity in affective disorders

Plasma dopamine beta hydroxylase (DBH) activity was measured in patients with affective disorders and in their relatives. The groups studied had wide distributions of values for plasma DBH activity. No significant difference of plasma DBH activity was found between unipolar and bipolar patients, nor between patients given lithium or placebo. Exercise on a treadmill at 40 degrees or 10 degrees C elicited a different pattern of response for plasma DBH activity in three patients as compared to control subjects. In familial studies we found the values of plasma DBH activity to be almost identical in monozygotic twin pairs and quite similar in dizygotic twin pairs. All pairs, however, were discordant for affective illness. There was also a marked similarity of plasma DBH activity in 15 pairs of the same sex sibs discordant for affective illness. These studies suggest that the resting level of plasma DBH activity is not related to affective illness but is genetically determined.

[Genetic study of mani-depressive psychoses]

The aim of the present work is to investigate the heredity of manic-depressive syndromes, in particular to test the hypothesis of a dominant X-linked transmission in these disorders. The Maximum Likelihood Estimate method was applied to linkage analysis between several X-linked genetic markers and bipolar manic-depressive illness, as well as to a control population of unipolar depressive patients. The genetic markers studied were deuteranopia and protanopia (two X-linked recessive markers) and the Xg blood group (X-linked dominant marker). The sampling methods were identical for both groups of patients and the family studies were performed "blind" (i,e. without knowledge of the proband's diagnosis). The results demonstrate the presence of strong linkage between manic-depressive (bipolar) illness, deuteranopia and protanopia. Linkage (although less strong) was also shown for bipolar illness and the Xg blood group. The genetic data are based on mathematical analysis of 36 informative kindreds ascertained from a sample of 134 manic-depressive patients. The results are concordant and demonstrate that, in this sample, manic-depressive (biopolar) psychosis is genetically transmitted through a X-linked dominant factor. We have also demonstrated the absence of linkage between unipolar depressive illness and the studied genetic markers in 16 informative kndreds ascertained from a sample of 71 unipolar patients. The genetic analyses described in this study demonstrate the existence of a manic-depressive syndrome which phenotype is dominant and determined by a gene located on the short arm of the Xchromosome. Apart from some forms of mental deficiency, manic-depressive psychosis represents the first known instance of a mendelian heredity machanism in psychiatric disorder;

Plasma levels of imipramine in depression. Environmental and genetic factors

On the basis of tentative evidence obtained with 26 patients with unipolar affective illness, the variability in the response to imipramine is mostly due to interindividual differences in hydroxylating microsomal enzymes which are genetically controlled but whose activities are subject to modification by environmental factors such as overall pharmacological exposure and tobacco smoking. Additional significant pharmacodynamic variability (twofold) was found in the range of the volumes of distribution of imipramine in the patients. Clinical outcome was unequivocally related to plasma level. Unipolar nondelusional patients with levels less than 180 ng/ml had a low probability of recovery, while levels above 180 ng/ml were assoicated with a high probability of recovery. Unlike the findings of investigators working with nortriptyline, our data do not suggest an upper limit on plasma levels beyond which clinical response deteriorates. It appears that, on the basis of family studies, similar genetic characteristics are related to the ones controlling the pharmacodynamics will be the subject of further examination in our continuing studies.

The contribution of genetics to biological psychiatry

One of the most striking developments in the framework of biological psychiatry, is the use of human as well as animal genetics' methodology in psychiatric research. After reviewing some basic concepts in human genetic research, we shall present the current status of our knowledge on the genetic determinants of the major psychoses, i.e., the affective psychoses and schizophrenia. The importance of genetic research into psychiatry can also be underscored from a biometric point of view in showing its contribution to the clarification of problem of nosology in attempting to subclassify abnormal behavior on a more etiological basis. Finally, a still open field essential to our comprehension of therapeutics emerges from the study of genetic mechanisms involved in drug metabolism and drug response.

Genetics of affective disorders. II. Morbidity risk and genetic transmission

Morbidity risk and genetic transmission data on a small population of bipolar, unipolar and schizo-affective outpatients suggest a possible genetic overlap between bipolar and schizo-affective patients. There is a conspicuous absence of a homologous illness in the relatives of schizo-affective probands, although the incidence of schizophrenia was higher in these relatives as compared to the relatives of either bipolar or unipolar probands. The data, although tentative because of the relatively small numbers involved, suggest a multifactorial mode of transmission in some affective illnesses. These disease entities appear familial rather than 'genetically transmitted'. There are select families who show the heritable genetic penetrance previously recorded for these mental disorders.

Genetics of affective disorders. I. Familial incidence study of bipolar, unipolar and schizo-affective illnesses

47 affectively ill psychiatric patients and their first-, second- and third-degree relatives were investigated by means of an interview and pedigree analysis to determine the incidence of psychiatric illness in their families. The percentage of psychiatric illness appeared greatest in families of bipolar and schizo-affective probands and least in families of unipolar depressives. In addition, we observed that often within a particular family constellation, more than one type of psychiatric illness (i.e., bipolar manic-depression, schizophrenia, alcoholism, etc.) was present. Morbidity risks varied from one affected family to another, indicating that the genetic risk components for some families are greater than for others. These findings are suggestive of multifactorial genetic disease but other genetic models are considered.

Accuracy of the family history method in affective illness. Comparison with direct interviews in family studies

We interviewed available spouses and first-degree relatives of 140 bipolar and unipolar probands for current and past psychopathology, and assessed interrater reliability. Diagnoses based on direct interviews of relatives were compared with those based on reports of the probands and of all other interviewed family members. Probands underestimated the prevalence of affective illness and other psychiatric disorders in their relatives, and overestimated the age of onset of illness in their ill relatives. Probands reported more accurately about illness in their spouses and parents than in their siblings and children, but accuracy reached acceptable levels for spouses only. Diagnoses on relatives derived by combining reports of all other interviewed family members, including the proband, were slightly more accurate than those based on the proband's reports alone. Good accuracy was obtained only for reports about spouses.

Double-blind procedure: an assessment in a study of lithium prophylaxis

Fifty-seven patients with primary affective disorder who were in a double-blind outpatient study to evaluate the prophylaxis of lithium were questioned as to whether they believed they were receiving lithium or placebo. Research nurses who were 'blind' to the patients' medication and a close relative living with each patient were also questioned. Nearly all patients (96%) said they beleived they were receiving lithium, ascribing this belief in 63% of the cases to a perceived improvement in condition. In only 14% of the cases on lithium was the presence of side-effects implicated in the patients' beliefs. One of the three nurses had a correct guess rate in excess of chance expectancy. All nurses tended to be more accurate in their guesses in the cases of patients who had been in prophylactic trials of over 15 months' duration than for patients with briefer periods in the study. Patients' relatives were, as a group, extremely accurate, their correct guess rate exceeding chance expectancy at the 0-001 level.

A genetic study of plasma dopamine beta hydroxylase activity in man

Plasma dopamine beta hydroxylase (DBH) activity was determined in MZ twins and in siblings of both sexes. The enzyme activities were found to be virtually identical in MZ twins. DBH activity was less similar in same-sex sibs, but still significantly correlated. These results indicate that plasma DBH activity is genetically determined.

Norepinephrine metabolism in mouse heart after lithium and rubidium treatment

This report describes the effects of treatment with lithium (Li), rubidium (Rb) and sodium (Na; 1 mEq/kg/day) for 7 days on norepinephrine (NE) turnover in mouse heart. The effects of several drugs which modify the uptake and storage of NE were also studied in similarly pretreated mice. A method based on the combustion of tissue tritium to tritiated water was used to assay tritiated l-norepinephrine (l-NE-3H) concentrations in individual hearts. The rate of decline of tissue tritium concentrations in groups of pretreated mice maintained at ambient temperature (23--24 degrees C) or in the cold (4--5 degrees C) was determined. The results indicate that, compared to Na, Li and Rb did not modify the tritium turnover rate in mouse heart. Pretreatment with Li or Rb did not modify the uptake of tritiated NE in the heart. The effects of desipramine. cocaine, bretylium and chlorpromazine on NE uptake were not altered by the alkali ions. Further, pretreatment did not modify NE release by tyramine, metaraminol and guanethidine. These studies suggest that Li and Rb do not modify NE uptake, release and storage in mouse heart.