Powershell AD Syntax - If Statement is duplicating a string

New scripter with hopefully an easy proofread.

I made an Powershell Active Directory script that processes people on Leave of Absence (LOA) within my organization from a daily CSV file I get.

In summary my problem segment should:

• Check the $Line variable's currentStatus if that employee is "On Leave"
• Disable that Active Directory account.
• Grab that AD account's 'Description' field and look for the string part "LOA - " and add that ONLY if it is missing. Problem is that if that field already has "LOA - " in the description, it puts another one... and another, so on.

Example:

• Description (Good): LOA - Chef
• Description (Bad): LOA - LOA - Chef
• Description (Please NO): LOA - LOA - LOA - Chef
• Etc.

I'm fairly certain the problem is with this line here but I can't figure out how to fix it.

If ($null -ne ($newDescript | ? {$loaPhrases -notcontains $_}))

$loaPhrases = "LOA -|LOA-|LOA - |LOA- |LOA - LOA - "

ElseIf ($Line.currentStatus -eq "ON LEAVE") 
{
    #Add 'LOA - ' to description and disable AD
    Set-ADUser $User.samAccountName -Enabled 0
    'Disabled AD'

    $Description = Get-ADUser $User.samAccountName -Properties Description | Select-Object -ExpandProperty Description
    $newDescript = $Description.substring(0, $Description.IndexOf('-')+1)
    If ($null -ne ($newDescript | ? {$loaPhrases -notcontains $_}))
    {
        $Description = "LOA - " + "$Description"
        $Description = $Description.trim()
        Set-ADUser $user.samAccountName -Description $Description
    }  
}