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| ORIGINAL ARTICLE |
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| Year : 2020 | Volume
: 7
| Issue : 2 | Page : 79-84 |
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Familial liability and age of onset among patients with major mental illness
Adetunji Obadeji1, Lateef Olutoyin Oluwole1, Christopher Goson Piwuna2
1 Department of Psychiatry, Faculty of Clinical Sciences, College of Medicine, Ekiti State University, Ado-Ekiti, Nigeria
2 Department of Psychiatry, Faculty of Medicine, University of Jos, Jos, Plateau State, Nigeria
| Date of Submission | 13-Apr-2020 |
| Date of Acceptance | 20-Jul-2020 |
| Date of Web Publication | 16-Sep-2020 |
Correspondence Address:
Adetunji Obadeji
Department of Psychiatry, Faculty of Clinical Sciences, College of Medicine, Ekiti State University, Ado-Ekiti
Nigeria
 Source of Support: None, Conflict of Interest: None
DOI: 10.4103/JNBS.JNBS_3_20
Familial liability (FL) or susceptibility has been shown to increase the risk for psychotic disorders, however, little is known about FL among patients with major psychiatric disorders in Nigeria. This study aimed to determine the rate of FL and factors influencing the age of onset among patients with schizophrenia and bipolar disorders (BDs). This was a cross-sectional survey of patients with either diagnosis of BD or schizophrenia based on ICD-10 criteria. Data were collected through a pretested sociodemographic questionnaire, incorporating age, duration of illness, the onset of illness, and family history (FH) of mental illness. Data were presented as tables, charts, and bivariate analysis was performed to determine the relationship between variables. The level of significance was set at P < 0.05. Of the 235 participants, 66 (28.1%) had a FH of mental illness. The age of onset ranges from 12 to 70 years with a mean of 30.1 years (standard deviation = 11.1 years) and majority 85 (36.2%) were within the age group 30–39 years and had developed the illness before the age of 30 years (54.5%). The males were twice more likely to developed mental illness before the age of 30 years compared with their female counterparts (odds ratio [OR] = 2.42, [confidence interval (CI) = 1.40–4.25], [P = 0.013]), likewise, the singles compared with the ever-married (OR = 4.24, [CI = 2.45–7.34], [P = 0.000]). Although nearly a third of the participants had a FL to mental illness, there was no association between the age of onset and FH of mental illness. However, the males and the singles were more likely to have developed mental illness at an earlier age compared with their counterparts.
Keywords: Age of onset, bipolar disorder, familial liability, schizophrenia
How to cite this article:
Obadeji A, Oluwole LO, Piwuna CG. Familial liability and age of onset among patients with major mental illness. J Neurobehav Sci 2020;7:79-84 |
How to cite this URL:
Obadeji A, Oluwole LO, Piwuna CG. Familial liability and age of onset among patients with major mental illness. J Neurobehav Sci [serial online] 2020 [cited 2023 Mar 24];7:79-84. Available from: http://www.jnbsjournal.com/text.asp?2020/7/2/79/295157 |
| Introduction | |  |
Schizophrenia and bipolar disorder (BD) are major psychiatric disorders with familial disposition. As noted by many researchers, the presence of family history (FH) is a major risk factor for these disorders.[1],[2],[3] Several factors increase the risk of mental disorders in the general population. Of these, studies from the western world have repeatedly reported the role of heredity in the risk for mental illness.[4],[5],[6] Familial liability (FL) or predisposition increases the risk of psychotic disorders by about five-fold independent of environmental influence.[6],[7] However, the additive effect of both environmental and familial predispositions increases the risk of developing psychotic disorders further.[7]
Although schizophrenia is strongly associated with schizophrenia and related disorders among first-degree relatives, the presence of other psychiatric diagnoses among first-degree relatives increases the individual's risk of schizophrenia.[6] According to Mortensen et al.,[6] the risk due to FH schizophrenia only is 6.0%, however, the population attributable risk due to FH of mental illness, in general, is about six times this value, thus showing the impact of other psychiatric disorders in predisposition to schizophrenia.
The risk of offspring developing schizophrenia increases with increase in the number of parents with the history of mental illness, with both parents with history of schizophrenia, the risk increases to about four folds compared with just one of the parents with such history.[8] Similarly, the risk of BDs increases to about five folds in offspring of couples with a history of BD compared to where only one of the parents is affected.[8] This suggests as FL increases, the risk of developing both schizophrenia and BDs increases. Nevertheless, the risk of developing schizophrenia due to the presence of FH of psychiatric disorders decreased as the age of onset increases,[1] and men were more at risk of both schizophrenia and BDs compared with women.[9],[10],[11]
Studies have shown that positive FH of mental illness is associated with poor prognostic factors including early onset, increased frequencies of relapse or severity of episodes and substance misuse.[12],[13],[14],[15] People with a positive FH of BD, recurrent depression, substance misuse, and other mental health difficulties are more likely to have an early age of onset of either schizophrenia or BDs.[12] Patients with early-onset, on the other hand, were more likely to present with an increased level of cognitive impairment, impulsivity, and poor outcome.[11],[13] The severity of symptoms of illness may furthermore be influenced by the interaction between FH and gender.[12]
In Nigeria, there are limited studies looking at the extent of FH among people with schizophrenia and BDs, and its relationship with age of onset. We, therefore, sought to determine the rate of occurrence of family liability, and identify factors associated with the age of onset as well as the relationship between positive FH and age of onset among patients with schizophrenia and BD.
| Materials and Methods | | |
Study setting and design
This cross-sectional survey was carried out at the Psychiatric outpatient of the Ekiti State University Teaching Hospital (EKSUTH), located in Ekiti State, Nigeria. The Hospital provides tertiary health care for people of the State and environs. Besides providing care in various specialties and subspecialties of Medicine, the hospital also provides mental health care for people of the state and its environs.
Study population and sampling
Participants were patients with either diagnosis BDs or schizophrenia based on ICD-10 criteria as evaluated by Consultant Psychiatrists attending the psychiatric outpatients of EKSUTH, Ado-Ekiti. In this study, consecutive patients with the diagnosis of either schizophrenia or bipolar affective disorders were recruited for the study through a convenient sampling technique. Data were collected over 3 months' period, with the mind that majority of the patients would have been seen at the out-patient clinic (based on the duration of appointment usually given).
Instrument
Consecutive patients with the diagnosis of either schizophrenia or bipolar affective disorder were interviewed with pretested sociodemographic questionnaires, that incorporates the age, sex, duration of illness, the onset of illness, and duration on medications. A FH of mental illness was also elicited with a pretested questionnaire on history of similar illness or other mental illness in the first- or second-degree relatives. Due to the low level of knowledge of mental illness by the participants and record-keeping generally, participants were not asked for specific psychiatric diagnoses, but a history of mental illness in the first- and second-degree relatives.
The functional recovery was assessed by the managing physician who responded to the question “Considering your total clinical experience with this particular population of patients, how mentally ill is the patient at this time? to assess extent wellness compared with healthy individuals or someone with mental illness on a 7-point Likert scale based on their experience with this population of patients (7 = among the most extremely ill patients, 6 = severely ill, 5 = markedly ill, 4 = moderately ill, 3 mildly ill, 2 = borderline mentally ill, 1 = normal, not at all ill, and 0 = not assessed).
The age of onset was dichotomized into two, using the mean age of onset as the cut off. The first group was those who have developed the illness on or before the age of 30 years and those who developed the illness after the age of 30 years.
Inclusion and exclusion criteria
Patients younger than 17 years or had not been receiving treatment for up to 6 months or had comorbid mental illness were excluded from the study.
Ethical considerations
The study protocol was approved by the Research and Ethics Committee of the EKSUTH, Ado-Ekiti. Written informed consent was obtained from all participants before the questionnaires were administered. The confidentiality of information provided by the participants was also ensured.
Data analyses
Data were analyzed using Statistical Package for Social Sciences (SPSS) version 25 (IBM Inc, IBM Inc. Armonk, New York, USA). Descriptive statistics including mean, frequency tables, and charts were performed to determine the distribution of characteristics of the variables studied. Chi-square test as well as the odds ratios were performed to determine the relationship between FH of mental illness, sociodemographic variables, and age of onset. A P ≤ 0.05 was adjudged statistically significant.
| Results | | |
Sociodemographic variables
A total of 235 patients with either schizophrenia or bipolar affective disorders took part in the study. Their ages range between 17 and 75 years with a mean of 38.5 years (standard deviation [SD] = 11.2 years). The age of onset ranges from 12 to 70 years with a mean of 30.1 years (SD = 11.1 years). As shown in [Table 1], the majority of participants 85 (36.2%) were within the age group of 30–39 years (36.2%), followed by those between 20 and 29 years (22.6%). Majority 128 (54.5%) developed the illness before the age of 30 years while 49 (21.4%) on or before the age of 21 years. Most of the participants were females 153 (61.5%), had tertiary education 129 (54.9%), single 119 (50.6%), and were employed 120 (51.1%).
[Table 2] shows the FH of illness and the diagnoses of the participants. A total of 203 (86.4%) had schizophrenia while the rest had bipolar affective disorder. Sixty-six (28.1%) had a FH of mental illness.
[Figure 1] shows the pie-chart showing the family relationship with the probands. The majority of the participants 24 (32%) reported siblings as relative with the history of mental illness, followed by mother (18%), and cousins were the least.
Relationships between the age of onset and participants' characteristics
[Table 3] shows the relationship between age of onset and participants' characteristics. Compared with the females, the males were more likely to developed mental illness before the age of 30 years (odds ratio [OR] = 2.42, [confidence interval (CI) = 1.40–4.25], [P = 0.013]). Similarly, the singles were over four times more likely to develop mental illness before the age of 30 years compared with those that were ever married (OR = 4.24, [CI = 2.45–7.34], [P = 0.000]). There was no statistically significant relationship between levels of education, participants' diagnosis, FH of mental illness, and age of onset of illness. | Table 3: Relationship between the age of onset and participants' characteristics
Click here to view |
Age of onset and functional recovery/severity of illness
[Figure 2] shows the relationship between age of onset and functional recovery/severity of illness. Compared with those with the onset of illness 30 years and above, a higher number of those with the onset of illness below 30 years were adjudged to be borderline to severely ill at the time of interview while a higher number of those that were rated normal had the onset of illness after the age of 30 years.
| Discussion | | |
Schizophrenia and BDs occur more frequently in first- and second-degree relatives of people with mental illness.[16] In this study, nearly a third of the participants reported FH of mental illness suggesting a high genetic predisposition. A FH of schizophrenia for example, had been reported as the strongest single indicator for an individual with schizophrenic risk.[6] The presence of an affected co-twin, first-degree, or second-degree relative increases the relative risk by about 2–38 times.[16] Similarly, the risks of schizophrenia and BD in offspring of couples with schizophrenia and the other with BD were 15.6% and 11.7%, respectively, as against 4.4% in offspring where only one of the parents is affected.[8] Familial predisposition has been reported to increase the risk of psychotic disorder by about five-fold independent of environmental influence.[6],[7] This suggests the effect of heritability in predisposition to schizophrenia and BD.
In this study, participants' age of onset ranges from 12 to 70 years with an average age of about 30 years, indicating most of the participants were relatively young. There was no significant difference in the age of onset of people with the diagnosis of schizophrenia and BD. This suggests that both disorders show a relatively young age of onset. Again, over half of the participants had developed mental illness before the age of 30 years while about one-fifth before the age of 21 years, denoting most had a relatively early age of onset. Similar to other psychiatric illnesses, most individuals with schizophrenia and BD developed these disorders in late adolescence or early twenties, with a slightly later onset in females.[17],[18] Several reasons have been deduced to explain this; the early adulthood represents a time of maturation and comes with its peculiar challenges.[19],[20] Studies have shown that patients with early-onset were more likely to show greater levels of cognitive impairment, a higher level of impulsivity as well as poor outcome.[11],[13] This may explain the lower-level functionality observed with most patients with early onset illness as noticed in this study.
The majority of the participants that were adjudged to have borderline to severe illness were more likely to have developed the illness before the age of 30 whereas those who were normal were more likely to have developed the illness after the age of 30 years. Studies have shown an association between age at onset and the outcomes.[15],[21],[22] Patients who were relatively young at onset were more likely to have more hospitalizations, more negative symptoms, more relapses, and poorer social and occupational functioning.[13],[21]
In this study, relative to their female counterparts, the males were more likely to develop a mental illness at an earlier age similar to other findings.[11],[17] This is not limited to schizophrenia alone but to BDs as well.[9],[10],[11] Among patients with schizophrenia on the other hand, a meta-analysis showed that the presence of a FH of psychosis is associated with an earlier age at onset in both sexes, with male gender presenting with early onset in those without FH of mental illness.[23] This is supported by a recent study focusing on illness course that reported no association between gender and age at onset after adjusting for severity of symptoms at presentation,[24] suggesting early age at illness onset might be a pointer to increased genetic vulnerability with gender as a modifier. Nonetheless, the presence of accumulated trauma, obstetric complications, and cannabis use may explain the relatively lower the age at onset in males.[24],[25]
Among patients with BDs on the other hand, studies examining the relationship between age at onset and gender have produced varying results.[10],[26],[27],[28] Significantly, men had been reported to present with earlier onset of first-episode mania and BD compared to women[10],[27],[28] while others had reported men and women had similar age of onset but differ in the type of episode at onset and comorbidity pattern.[26]
Oftentimes, the onset symptoms of schizophrenia begin in the 2nd and 3rd decade of life, though the onset may be earlier or later, and may even extend to the 7th decade of life.[17] This may explain the long-range of age-onset noted in the study. However, some authors had raised the possibility of those disorders occurring at the later end of life as other variants.[29],[30]
Varying findings have been reported on the impact of the FL of mental illness.[12],[31],[32] Positive first-degree FH of psychosis had been reported to be associated with younger age at onset.[12],[33] However, there was no significant relationship between familial predisposition and age of onset in this population. Other environmental factors such as trauma, life adversity, obstetric complications which are likely to be more prevalent in this environment may explain this finding. Nevertheless, the risk of developing schizophrenia as a result of familial disposition decreased as the age of onset increases.[1] Furthermore, there was no significant difference in the age of onset of both schizophrenia and BD, suggesting similar factors may influence the age at onset.
Compared with those that were ever married, participants who were single were more likely to have developed the illness before the age of 30 years. Marriage has been reported to be associated with reduced risk of early onset of most mental disorders in both males and females.[34],[35] Nevertheless, individuals with major mental illness are at higher risk of marital dissolution, or less likely enter into new marriages.[35] Although marriage acts as a protective factor, it may also act as a predisposing/precipitating factor for most psychiatric disorders.[36] Nonetheless, longitudinal studies are needed to provide greater clarity on the temporal association between the age of onset of mental health symptoms and marital status.
A substantial number of participants had a FH of mental illness, mostly as siblings and parents. However, no association was found between age of onset and FH of mental illness, suggesting other factors may contribute to early onset. Males and singles were more likely to develop mental illness earlier compared with their females or ever married counterparts. Similarly, those with early age of onset were more likely to present with more severe form compared with those who developed the illness at an older age.
(Abbreviations: BD: Bipolar Disorder, FH: Family History, FL: Familial Liability, SPSS: Statistical Package for Social Sciences.)
Ethics committee approval: The ethics committee approval has been obtained from Ekiti State University Teaching Hospital with Ethics and Research committee report number of EKSUTH/A67/2019/09/019 (10 Oct 2019).
Patient informed consent: Informed consent was obtained.
Financial support and sponsorship
No funding was received.
Conflicts of interest
There is no conflicts of interest to declare.
Author contribution area and rate:
Adetunji Obadeji (%50): conception/design of the work, data acquisition, analysis interpretation and drafting and its critical revision for important intellectual content.
Lateef Olutoyin Oluwole (%28): involved in refining the conception of the work, the interpretation of data for the work and revising it critically for important intellectual content.
Christopher Goson Piwuna (%22): involved in refining the conception of the work, the interpretation of data for the work and revising it critically for important intellectual content.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3]
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