The recent rate of use and abuse of psychoactive substances in Nigeria has attracted interests of many and become issue of worry [1]. For instance, Nigeria is currently rated the highest consumer of cannabis and amphetamines in Africa [2]. It was further observed in a recent large study of a representative sample of Nigerian adults that the proportions of use of these substances to be alcohol 58%, tobacco 17%, sedatives 14%, substance 2.4% and 3% cannabis. It has, however, been suggested that the emerging trend in substance abuse in the country was apparently due to lack of existing international and local interventions in Nigeria, calling for a need to find an effective and suitable solution to the menace before it gets out of hand [1].

The broad range of substance abuse in the contemporary society is ever expanding [3]. More Nigerian are becoming drug addicts, while Nigeria gradually graduates from a drug consuming nation to a drug producing one. Despite several efforts by the Nigerian Drug Law Enforcement Agency to contain the diverse problems of illicit drugs production, circulation, marketing and consumption in Nigeria, more people are being recruited daily by drug barons to serve as couriers just as many more, especially youths are increasingly becoming addicted to assorted drugs [4] [5]. Substance use behavior in Nigeria was identified to be more prevalent among military and paramilitary officers especially, substances that are majorly common in Nigeria, such as hemp, methamphetamine, syrups and tablets with codeine. To most non-military or paramilitary substance abusers in the rehab, the most common source of purchase is military barracks, and establishments around or within barracks, such as schools, motor parks and even local traders [6].

Aside from ensuring adequate security outside the country, the paramilitary force (PMF) ensures internal security, providing safety and security of people and materials at instances of elections and other national assignments, and disaster management. Officers of PMF are at a high risk of being exposed to stress as a result of their job situations, which subsequently predispose them to experiencing negative emotions such as anxiety, frustration, and dysfunctional anger. In addition, the nature of their job such as intra or inter-country posting, distanced family, inadequate remuneration among others pose much pressure to the psychological wellbeing this in turn make them more susceptible to some unhealthy behavior such as substance abuse.

Substance use and abuse among the paramilitary officers therefore equally become a serious matter of concern with evidence suggesting certain personality traits as psychological correlates of the hazardous behavior [7]. Men and officers of the Nigeria immigration service officers are not left out, due to the regimental nature of their job and other factors. The patterns of drug and alcohol used among officers of Nigeria immigration service are not left out of the worrisome phenomenon of substance use disorder.

A number of risk factors have been implicated in the etiology of substance abuse behavior among different groups. These risk factors range from personality traits of impulsivity, negative affectivity, cognitive distortions, low self-esteem, peer pressure, frustration, etc. [8]. Of these factors, the current study aims at exploring psychological (personality) factors that relate to the motivation for drug and alcohol use among officers of Nigeria immigration Service. Personality traits have earlier been identified as core factors that attempt to explain why some officers are drawn to substance use [9].

Personality types of individuals play a significant role influencing the behavioral outcome of substance use and abuse. For instance, the type of personality of an individual may serve as either predisposing or protective factor in individuals' involvement in drugs of abuse. For instance, neurotic people have a higher tendency to experience negative affect such as frustration, depression, anxiety among others, this makes them more likely to turn to psychoactive substances as a form of coping with their negative usual affects especially when confronted with stressors.

In a related study by Ifeagwazi on personality traits and substance abuse, he concluded that there is a strong relationship between neuroticism and substance abuse. According to him, high scorers in neuroticism experience various negative emotions such as anxiety, depression, anger, shame, guilt, sadness and hostility. These negative unpleasant states have been linked with alcohol and drug abuse. Similarly, Anderson revealed that participants with high scores on psychoticism exhibit some personality and behavioral traits such as impulsivity, aggressiveness, egocentrism and antisocial tendencies and these traits have been shown to correlate with substance abuse [9][10] [11].

Spiro and Turiano further explained that neuroticism personality trait is associated with substance use, with high neurotic individuals being more likely to smoke cigarettes and smoke a greater quantity of cigarettes [12]. Terracciano, Lockenhoff, Crum and Costa asserted that those high in neuroticism personality are also more likely to abuse alcohol [13]. Furthermore, in a longitudinally study conducted by Hampson et al., evidence provided suggests that children rated low in emotional stability predicted greater alcohol use later in life, some 40 years later in middle age [14]. The overall domain of neuroticism and underlying facets such as negative affect also been have positively related with marijuana, cocaine, and heroin use [15].

Substance use among paramilitary officers is not without negative effects which may be sometimes severe. For instance, impairment in personal relationships, occupational and social functioning, which may translate to poor service discharge, corruption and irregularities, domestic and workplace violence and even death of abusers may not be far from individuals caught up in the habit of use and abuse of psychoactive substances.

Versed knowledge of the relationship that exists between personality and substance abuse therefore become immense which could turn out useful in the management of officers who abuse substances. In this regard, the current study investigates relationship of personality factors and implications on substance abuse among officers of the Nigeria immigration services. In order to achieve the objective of this study, we hypothesized a significant positive relationship between neuroticism personality trait and substance abuse among officers of the Nigeria immigration service. We also expect that there will be a significant negative relationship between psychoticism personality trait and substance abuse among officers of the Nigeria immigration service.

Research Design
The research design for this study is a non-experiment correlational design. The research design enable researcher to establishment the relationships that exist between the independent variables and the dependent variable.

Participants
One hundred and fourteen (114) officers of the Nigeria immigration service from three different commands in South-West, Nigeria; Lagos Marine Command, Osun State Command, and Zone F Zonal Command Ibadan participated in the study. Their age ranges between 24 and 55 years. The respondents comprised 71% (82) male and 28.1% (32) female.

Instruments
Structured questionnaires were used to collect data in the present study. The questionnaire is made up of three sections. Section one elicited demographic data, section two measured the personality profile of respondents focusing on Neuroticism subscale, and psychoticism subscale, while the third section comprised of a measure of substance abuse as measured by PSCAI.

The Neuroticism scale used in the study is the subset of personality inventory developed by Eyesenck and Eyesenck [16] and standardized for Nigerian use by Eyesenck, Adelaja, and Eyesenck [17]. The 23 items neuroticism scale is reliably validated. The Nigeria norms provided are as follows males 6.43; female 8.42. The items are scored as '1' point for a 'yes' response in neuroticism [17]. The psychoticism scale used in the study is also the subset of personality inventory developed by Eyesenck [16]. The 25 items psychoticism scales are reliable and validated. The Nigeria norms are as follow; males 4.6, females 2.97 for the 1st 14 items scored '1' point for a 'yes' respond while 11 other items carry'1' point or a 'no response'.

The psychological correlated of substance abuse index (PCSAI) was developed and validated Etim and Ottu [18]. The scale is a 22-item instrument with 5-point Likert format of 'strongly agree, agree, undecided, disagree and strongly disagree. The PCSAI is designed to measure the level of respondent's psychological predisposition to substance use/abuse behavior. The scale yields a coefficient alpha reliability estimated at 0.88 in the present study.

Procedure
Questionnaires were administered to the 114 participants in a conducive environment after the purpose of the study has been well explained to them and they consented to participate in the study. The participants were selected through the use of purposive sampling technique. All the questionnaires administered were returned but 106 were found usable for data analysis.

Hypothesis 1
Hypothesis one stated that there will be a significant positive relationship between neuroticism personality trait and substance abuse among officers of the Nigeria immigration service. The hypothesis was tested using Pearson Product Moment Correlation (PPMC). The result presented in Table 1 showed that there is a significant positive relationship between neuroticism personality trait and substance abuse (r = 0.46, df = 105, p < 0.01). This result implies that immigration officers who are more emotionally unstable are more likely to be involved in substance use or abuse. The hypothesis stated was therefore accepted.

Hypothesis 2
Hypothesis two stated that there will be a significant positive relationship between psychoticism personality trait and substance abuse among officers of the Nigeria immigration service. The hypothesis was tested using Pearson Product Moment Correlation (PPMC). The result presented in Table 2 showed that there is no significant relationship between psychoticism personality trait and substance abuse (r = -0.10, df = 105, p > 0.05). The stated hypothesis two was therefore rejected.

The present study examined the personality factors as correlates of substance abuse among officers of Nigeria immigration service. It was established that there is significant relationship between neuroticism personality trait and substance abuse. Similarly, the study of Spiro and Turiano, which revealed that neuroticism has clear associations with substance use, he further claimed that neurotic individuals being more likely to smoke cigarettes and smoke a greater quantity of cigarettes [12]. Empirical evidence indicates that persons with high scores on neuroticism i.e., emotional unstable are predisposed to psychological challenges including anxiety, depression, anger, shame, guilt, sadness, and hostility and these negative unpleasant states have been linked with alcohol and drug use [9]. This may be the reason participants with emotional instability tend feel their emotions as negative and might seems unpleasant to them, this would therefore pave way for the quest of getting out of such emotional feelings as such resort into substance abuse because of its euphoric feelings and emotional make up.

The present study further established that there is no significant relationship between psychoticism personality trait and substance abuse. The study further revealed the direction of the insignificant relationship that exists between the two variables to be negative. This outcome did not align with the assertion of Anderson in a similar research work which revealed that participants with high scores on psychoticism trait exhibited behavior that have been shown to correlate with substance abuse [9].

The authority in the Nigeria immigration service should take into consideration the salient impact of personality in the predisposition to the abuse of substances among officer of the paramilitary. Training and workshop should be conducted periodically for the vulnerable officers (officers with high scores on neuroticism scale) and training should entails adequate supplement psychological skills that can stabilizes ones emotional instability such as relaxation training, stress inoculation training, objective coping skill, etc. Future research should replicate similar research interest among drug abused inpatient undergoing treatment.

This study investigated the personality factors as correlates of substance abuse among officers of Nigeria immigration service. From the findings of the study it was established that neuroticism personality trait positively correlated with substance abuse significantly, while psychoticism personality trait did not significant correlate psychological correlates of substance abuse.

We are thankful to Olaseni Victory Nifemi, Olaseni Morenike Vivian, Agberotimi Femi for their help and support.

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